HK40109993A - Redox microfluidic energy storage system and method - Google Patents

Description

Redox Microfluidic Energy Storage System and Method

Technical Field

This invention belongs to the field of energy storage and management. More specifically, this invention relates to a redox microfluidic energy storage system and method using a redox flow battery formed by multiple interconnected membrane-free battery microcells. The electrolyte containing active material can move or pass through the battery microcells in a laminar flow state, thereby eliminating the need for selective ion exchange membranes or any other type of physical separator or barrier between the electrolytes. Furthermore, all components of the redox microfluidic energy storage system (except for the electrolyte storage tank) are designed and manufactured on a microscale and can be mounted or integrated onto a single microchip.

Background Technology

Energy storage refers to capturing energy generated initially for later use, thereby reducing the imbalance between energy demand and energy production. Devices for storing energy are commonly called batteries or storage units. Energy exists in many forms, including radiation, chemical energy, gravitational potential, electric potential, electrical energy, high temperature, latent heat, and kinetic energy. Energy storage involves converting energy from difficult-to-store forms into more convenient or economical storage methods. Today, the importance of energy storage stems from three main factors: a decreasing shift in the energy demand curve, the development of smart grids, and the integration of renewable energy sources into the grid. Due to the intermittent nature of energy demand, the development and improvement of energy storage systems have become increasingly urgent. Some recently developed methods and systems for energy storage include electrochemical batteries (e.g., lithium-ion batteries, lead-acid batteries, or sodium-sulfur batteries) and redox flow batteries.

A flow battery is a reversible energy storage system or device capable of storing energy through an electrochemical process. All electrochemical energy storage systems convert electrical energy into chemical energy during charging and vice versa during discharging. In conventional electrochemical batteries, energy conversion and storage occur simultaneously within the battery reaction cells. However, in flow batteries, energy conversion and energy storage are separate. Therefore, flow batteries differ from conventional electrochemical batteries in that energy and power can be separated and scaled independently. In such flow batteries, power is determined by the size of the battery cells and/or the number of cells stacked, while the amount of stored energy (i.e., battery autonomy) is determined by the amount of energy storage medium/material. Flow batteries typically consist of two tanks, two pumping systems with integrated flow control, and a reactor. They operate by pumping different chemicals stored in the tanks to the reactor, where a chemical reaction that generates electrical energy occurs. Flow batteries require the energy storage material to be in a liquid state.

A redox flow cell is a type of flow cell in which redox reactions occur at electrodes located inside a reactor.

Fluid behavior at the microscale differs significantly from that at the macroscale. A key effect of microscale fluid behavior is the extremely high surface area to volume ratio, which improves fuel efficiency and leads to more compact reactors. Specifically, at the microscale, surface tension and viscosity are the dominant forces, and the Reynolds number (the ratio of inertial to viscous forces within a fluid due to varying fluid velocities) is typically less than 100. This means that the fluid moves uniformly in a specific flow direction within the channel, and turbulence is absent. Therefore, at the microscale, fluid flow is always laminar, and only molecular diffusion is involved in the mixing of the fluid.

Therefore, manipulating fluids at the microscale means shorter residence times for charge carriers to exchange within the fluid, which in turn implies higher energy transfer rates. Another key aspect of manipulating fluids at the microscale is the ability to remove physical barriers (such as membranes or the like) that separate the electrolyte, thereby significantly reducing the internal resistance of the battery cell, improving battery efficiency and performance, simplifying design, and reducing costs.

Known membrane-free redox flow cells are typically based on the co-layered nature of microscale flows without requiring physical barriers between them. While preventing chaotic flow, these devices still introduce significant advection mixing due to electrolyte viscosity differences that cause interphase displacement and the lack of a suitable management system to compensate. Therefore, current microflow cells only partially separate the electrolyte reactants, making operation as a flow battery with multiple charge/discharge cycles impossible. Interdiffusion is limited to a diffusion-mixed layer between the electrolytes. This diffusion-mixed layer can be controlled by selecting appropriate cell design and suitable flow rates of the fluid through the cell. However, the lack of separating elements between electrolytes, coupled with faster diffusion of materials, can lead to increased cross-effects or mixing between active materials, and consequently, capacity loss due to self-discharge processes. Furthermore, much of the progress in this technology exists only at the experimental level, as simple cell prototypes, without integration into complete operational designs. Proper design and integration of each element in a redox flow battery is a critical factor for its full operation. Currently, a solution capable of successfully addressing the aforementioned problems remains unclear.

Advances in microfluidics and microelectromechanical systems (MEMS) technologies have enabled the development and fabrication of devices such as micropumps and microvalves, which allow for highly precise control of flow at the microscale. These devices also offer other advantages, including reduced size and weight, excellent portability, low power consumption, wide flow range, low cost, the possibility of integration with other microfluidic devices, low leakage, fast response, and linear operation. Meanwhile, microfabrication technologies have also been applied to the field of microfluidics.

Despite numerous efforts in the development of redox flow batteries, there remains a need in the existing technology for storage systems that can integrate membrane-free redox flow batteries into microfluidic systems to improve control of the electrolyte flowing within the reactor, thereby optimizing the charge/discharge performance of such systems and extending their lifespan.

Summary of the Invention

The first object of this invention is a redox microfluidic energy storage system, comprising a battery reactor, a positive electrolyte tank for storing a positive liquid electrolyte, a negative electrolyte tank for storing a negative liquid electrolyte, a battery management system, and a flow circulation system. The battery reactor comprises multiple membrane-free battery microcells connected to each other. Preferably, the membrane-free battery microcells are fluidly connected in parallel, and they may also be electrically connected in parallel or series. As used herein, a membrane-free battery microcell is a battery cell that operates at a microscale without a membrane or any other type of physical barrier or separator between the electrolytes flowing through the respective microcell. The membrane-free battery microcell relies on the properties of the microscale flow to maintain contact but separation of the electrolyte flows without mixing between them.

Each battery microcell includes a positive electrode half-cell housing a positive electrode and a negative electrode half-cell housing a negative electrode. These two half-cells are fluidly connected and positioned relative to each other. By positioning the half-cells relative to each other, the resistance to diffusion of ionic charge carriers from one electrolyte to another is minimized. Preferably, multiple battery microcells are stacked, but other arrangements are also possible.

The flow circulation system includes: a first micropumping system configured to supply a positive electrode liquid electrolyte from a positive electrode electrolyte tank to a positive electrode half-cell; and a second micropumping system configured to supply a negative electrode liquid electrolyte from a negative electrode electrolyte tank to a negative electrode half-cell. These first and second micropumping systems are independent of each other, such that the positive and negative electrode liquid electrolytes are in contact only within their respective battery microcells. The first and second micropumping systems are configured to supply the positive and negative electrode liquid electrolytes, respectively, at flow rates such that the positive and negative electrode liquid electrolytes are in a laminar flow state within the battery microcell. The positive and negative electrode liquid electrolytes are in direct contact within the membrane-free battery microcell, forming an interphase therebetween for transferring ionic charge carriers between the liquid electrolytes. Therefore, only molecular diffusion is involved in the mixing of the positive and negative electrode liquid electrolytes. The flow rates at which the positive and negative electrode liquid electrolytes are supplied to the battery reactor can be substantially the same or can be different. In addition to the micropumping systems, the flow circulation system may also include other components to manage, monitor, and modify the electrolyte flow between the tank and the battery reactor. Examples of such components are microvalves, flow meters, etc. Furthermore, a micro-pumping system can be formed by one or more micro-pumps or any other fluid micro-pulse devices connected in series or parallel with each other.

As used in this article, ionic charge carriers can refer to those free particles that carry charge that can be transferred between electrolytes to compensate for charge changes caused by redox reactions occurring within the battery reactor.

The battery management system is configured to supply liquid electrolyte to the battery reactor at a desired rate via a flow circulation system, and simultaneously supply current through the electrodes to charge the redox microfluidic energy storage system, or to supply liquid electrolyte to the battery reactor at a desired rate via a flow circulation system, such that current is released through the electrodes to discharge the redox microfluidic energy storage system.

A discharge process occurs when the chemical potential between the electrodes is high enough to generate an output current through the electrodes, while a charging process occurs when an external current is applied to the electrodes.

The integration of a microscale redox cell reactor with a microfluidic circulation system provides extremely precise and tight control over the flow of electrolytes at the microscale within the cell reactor. This allows for the avoidance of using membranes or other physical barriers between electrolytes and increases the ionic charge carrier mobility between electrolytes within the cell reactor, while significantly minimizing cross-effects or mixing between electrolytes.

As used herein, a battery management system may be at least one of a central processing unit (CPU), a semiconductor-based microprocessor, a programmable PLC, a graphics processing unit (GPU), a field-programmable gate array (FPGA) configured to retrieve and execute instructions, other electronic circuitry suitable for retrieving and executing instructions stored on a machine-readable storage medium, or a combination thereof, which will perform the functions disclosed herein. The battery management system may be fed data from various sensors throughout the redox microfluidic energy storage system and/or from other external devices, and will manage the operation of the redox microfluidic energy storage system.

As used herein, a flow circulation system refers to an integrated component designed to precisely and accurately pump and control the flow rate of each electrolyte stream. The appropriate flow sequence for a flow circulation system can be established based on several factors, including the state of charge and operating mode of the redox microfluidic energy storage system, the flow range of 0 to 1000 μl/min in each reaction microchannel of the battery reactor, and ensuring the laminar flow state of the electrolyte through the reaction microchannels.

In some embodiments, the battery management system is configured to adjust the electrolyte flow rate within the battery reactor based on at least one of the state of charge of the redox microfluidic energy storage system, the current value circulating through the electrodes, and the power to be delivered by the redox microfluidic energy storage system or the power received from an external source. The current circulating through the electrodes may be a current supplied by an external source during the charging process or a current generated in the electrodes during the discharging process. The battery management system may receive requests for the redox microfluidic energy storage system to deliver a specific amount of power to a power-consuming device, or requests for the redox microfluidic energy storage system to store a specific amount of energy by receiving a specific amount of power from an external source (more specifically, in the electrolyte of the redox microfluidic energy storage system). These requests may be provided by a user or by an external device that directly requests a certain amount of power by consuming energy in the redox microfluidic energy storage system, or directly requests the delivery of a certain amount of power to store energy in the redox microfluidic energy storage system. The electrolyte flow rate determined by the battery management system will be the minimum flow rate of electrolyte within the battery reactor required to ensure that the redox reaction occurs at the desired rate and to maintain the laminar state of the electrolyte.

In some embodiments, the battery management system includes a power management unit, an interphase management unit, and a fluid management unit. The power management unit is configured to receive a request and determine whether a stoichiometric flow rate setpoint is feasible for the required amount of power to be delivered or consumed in the redox microfluidic energy storage system. To this end, the power management unit may check the current state of charge of the battery redox microfluidic energy storage system to determine whether sufficient energy is stored in the system to deliver the required amount of power, or whether there is sufficient storage capacity in the system to store more energy at the required amount of power. If so, the battery management system is configured to calculate the corresponding stoichiometric flow rate setpoint. The interphase management unit is further configured to determine the corresponding flow rates of the positive and negative liquid electrolytes at the inlet and outlet of the battery reactor based on the calculated stoichiometric flow rate setpoint. The fluid management unit is further configured to determine an operating mode of the flow circulation system such that the determined flow rates at the inlet and outlet of the battery reactor are achieved. The operating mode of the flow circulation system may determine operating parameters of all or part of the components of the flow circulation system that may affect the flow rates at the inlet and outlet of the battery reactor. For example, operating parameters could be the pumping power of the micropump or a specific channel of the microvalve, as well as many other operating parameters of these or other components of the micropumping system. The power management unit, interphase management unit, and fluid management unit include the hardware and software required to perform the functions disclosed herein.

In some embodiments, the positive electrode half-cell and the negative electrode half-cell of each battery microcell define a reaction microchannel therebetween, through which the positive and negative liquid electrolytes flow in parallel in a laminar flow state. Interdiffusion between the electrolytes is typically limited by the interface width at the center of the reaction microchannel.

In some embodiments, the redox microfluidic energy storage system includes flow regulation devices arranged in microfluidic conduits of a flow circulation system between the outlet of the battery reactor and a corresponding tank. These flow regulation devices are configured to adjust the flow rate of the fluid electrolyte exiting the battery reactor based on the viscosity difference between the two fluid electrolytes, preferably by adjusting the channels of the microfluidic conduits to balance the interphase between the two electrolytes within the battery reactor. The viscosity of the electrolytes will vary with redox material exchange (i.e., ionic charge carrier exchange) and changes in the oxidation state of the active material due to redox reactions. Therefore, depending on the state of charge of the microfluidic energy storage system, the viscosity of each electrolyte will differ, and such viscosity differences between the two fluid electrolytes should be compensated for to maintain an intermediate interphase and minimize cross-mixing. To measure the viscosity of the electrolytes, the redox microfluidic energy storage system may include a viscometer arranged in the microfluidic conduits through which the electrolyte flows. Alternatively, the viscosity of the electrolyte in a redox microfluidic energy storage system can be determined based on the pressure difference between the electrolytes measured by pressure sensors arranged in the corresponding microchannels, or derived from the state of charge value (which can be obtained and used using relevant ex-situ curves), or obtained using a colorimeter (in some active materials, the color of the electrolyte is directly related to the amount of redox substances it contains). In this way, advection mixing of the electrolytes is avoided, thereby significantly improving the efficiency and capacity of the redox microfluidic energy storage system and delaying the need for chemical reequilibration.

In some embodiments, the flow regulating device may be a piezoelectric microvalve, a pneumatic microvalve (e.g., a seismic valve), or a shape memory alloy (SMA) valve, etc. Microvalve (i.e., a valve at the microscale) are configured to regulate or modify their channels by changing the hydraulic diameter of their cross-section, thereby altering the flow rate of fluid passing through the microfluidic conduit. They offer extremely high control over the channels and the fluid flow through them. Piezoelectric microvalves contain actuators that are more robust and simpler than other types of valves.

In some embodiments, the redox microfluidic energy storage system includes a pneumatic compressor fluidly connected to a corresponding pneumatic microvalve, wherein the pneumatic compressor is configured to actuate the pneumatic microvalve. These pneumatic compressors use air to actuate the valves so that they open or close to regulate their passages. These pneumatic microvalves offer higher stability, resolution, and accuracy than other valves, allowing for better control of the fluid flowing through them.

In some embodiments, the micropumping system includes a micropump, preferably a piezoelectric micropump, to supply a liquid electrolyte to the battery reactor. As used herein, a micropump can refer to a pump with a functional size at the microscale. The micropumping system may include a single micropump or may include multiple micropumps connected in series to better control the flow rate of the pumped fluid and achieve high pumping rates.

In some embodiments, the flow rates of the positive and negative electrode fluid electrolytes within the membrane-free battery microcell are selected from a range of 0 to 1000 μl per minute. Such flow rates ensure laminar flow of the electrolytes through the reaction microchannels of the microcell.

In some embodiments, the redox microfluidic energy storage system includes a first inlet flow sensor and a first outlet flow sensor arranged in corresponding microfluidic conduits of the flow circulation system, and a second inlet flow sensor and a second outlet flow sensor arranged in corresponding microfluidic conduits of the flow circulation system. The first and second inlet flow sensors are configured to measure the flow rates of the positive and negative electrode liquid electrolytes at the inlet of the battery reactor, respectively. Furthermore, the first and second outlet flow sensors are configured to measure the flow rates of the positive and negative electrode electrolytes at the outlet of the battery reactor, respectively. In some other embodiments, different numbers of flow meters may be present at different points in the microfluidic loop. The redox microfluidic energy storage system may also incorporate other types of sensors, such as viscometers, pressure sensors, temperature sensors, etc., arranged at different points in the redox microfluidic energy storage system.

In some embodiments, the battery reactor and the flow circulation system are integrated into the same body, such as a solid module. Thus, the battery reactor and the flow circulation system are developed at the microscale and integrated into a compact module. In some examples, at least some components of the redox microfluidic energy storage system may be integrated or formed within the body, and other components may be detachably or fixedly attached to the outer surface of the body.

A second objective of this invention is a charging method for a previously described redox microfluidic energy storage system. This method includes the following steps:

The first micro-pumping system supplies positive electrode liquid electrolyte to the positive electrode half-cell of the battery microcell;

The second micro-pumping system simultaneously supplies negative electrode liquid electrolyte to the negative electrode semi-micro cell of the battery micro cell;

Current is applied to the positive and negative electrodes of the battery microcell, while the positive and negative liquid electrolytes simultaneously flow in laminar flow through the positive and negative electrode semi-microcells respectively. This causes the redox reaction of the active material in the electrolyte to occur at the electrode surface, and ionic charge carriers transfer between the two electrolytes to compensate for the change in the oxidation state of the active material, thereby generating a chemical potential difference between the positive and negative electrode liquid electrolytes; and

The positive electrode liquid electrolyte and the negative electrode liquid electrolyte are stored in the positive electrode electrolyte tank and the negative electrode electrolyte tank, respectively.

In some embodiments, the method further includes receiving, at the power management unit of the battery management system, a request to determine the amount of power required to store energy in the redox microfluidic energy storage system (more particularly in the electrolyte of the redox microfluidic energy storage system). The power request may be provided by a user or an external device that will provide the energy to be stored.

The power management unit then determines whether a stoichiometric flow rate setpoint capable of storing a specific amount of power is feasible. To do this, the power management unit can check the current state of charge of the battery redox microfluidic energy storage system to determine if there is sufficient storage capacity in the system to store energy at the required power level.

If reaching the stoichiometric flow rate setpoint is feasible, the power management unit calculates the corresponding stoichiometric flow rate setpoint, and the interphase management unit of the battery management system determines the required flow rates of the positive and negative liquid electrolytes at the inlet and outlet of the battery reactor to reach the calculated stoichiometric flow rate setpoint. Subsequently, the fluid management unit of the battery management system determines the operating mode of the flow circulation system, such as the first and second micro-pumping systems and the operating mode of the microvalve arranged at the outlet of the battery reactor, to achieve the determined flow rates at the inlet and outlet of the battery reactor.

In some embodiments, the battery management system actively monitors the state of charge of the redox microfluidic energy storage system and performs the steps of the previously disclosed method until the maximum energy capacity has been reached and/or the power request for stored energy has been completed. The battery management system may monitor the state of charge of the redox microfluidic energy storage system in a continuous or periodic manner.

A third objective of this invention is a discharge method for a previously disclosed redox microfluidic energy storage system. This method includes:

A positive electrode liquid electrolyte is supplied to the positive electrode half-cell of the battery microcell by a first micro-pumping system. A chemical potential difference exists between the previously stored positive electrode liquid electrolyte and the negative electrode liquid electrolyte in the tank of the redox microfluidic energy storage system, thus enabling the discharge process to occur.

Simultaneously, a second micro-pumping system supplies negative electrode liquid electrolyte to the negative electrode semi-micro-cell of the battery micro-cell, causing the redox reaction of the active material in the electrolyte to occur at the electrode surface, and ionic charge carriers to transfer between the two electrolytes to compensate for the change in the oxidation state of the active material, releasing the current circulating through the electrodes of the positive and negative electrode semi-micro-cells; and

The positive electrode liquid electrolyte and the negative electrode liquid electrolyte are stored in the positive electrode electrolyte tank and the negative electrode electrolyte tank, respectively.

In some embodiments, the method includes receiving a request at the power management unit of the battery management system instructing the redox microfluidic energy storage system to deliver an amount of power. This request may be provided by a user or by an external power-consuming device requiring the requested power. The power management unit then determines whether a stoichiometric flow rate setpoint is feasible for delivering the specific amount of power. The power management unit may check the current state of charge of the battery redox microfluidic energy storage system to determine if sufficient energy is stored in the system to deliver the required amount of power. If feasible, the power management unit calculates the stoichiometric flow rate setpoint, and the interphase management unit of the battery management system determines the flow rates of the positive and negative liquid electrolytes at the inlet and outlet of the battery reactor based on the calculated stoichiometric flow rate setpoint. Subsequently, the fluid management unit of the battery management system determines the operating mode of the flow circulation system, such as a micro-pumping system and the operating mode of a microvalve arranged at the outlet of the battery reactor, such that the determined flow rates at the inlet and outlet of the battery reactor are achieved.

In some embodiments, the method includes monitoring the state of charge of the redox microfluidic energy storage system by the battery management system in a continuous or periodic manner, and performing the steps of the foregoing method until the minimum energy capacity of the battery has been reached and/or the power request for energy transfer has been completed.

Compared to previous devices, the redox microfluidic energy storage system described herein presents several advantages and/or differences. In particular, this solution integrates a membrane-free redox flow battery into the microfluidic system, providing reliable and accurate control over the electrolyte flow within the reactor, which operates in a laminar state, to optimize the charge/discharge performance of such systems and extend their lifespan. It also minimizes cross-effects between electrolytes and makes battery operation more stable. By operating at the microscale, the overall performance and efficiency of the redox microfluidic energy storage system are further improved. Other advantages include reduced manufacturing costs, as microfabrication requires lower initial investment than large-scale manufacturing, and reduced costs associated with simplifying battery reactor design due to the physical barriers separating the electrolytes. Avoiding the use of these physical barriers also extends the operational life of the battery reactor.

Attached Figure Description

To complete the description and to provide a better understanding of the invention, a set of accompanying drawings has been provided. These drawings form part of the specification and illustrate embodiments of the invention, and should not be construed as limiting the scope of the invention, but are merely examples of how the invention can be practiced.

The attached figures include the following:

Figure 1 shows a block diagram of a redox microfluidic energy storage system according to a specific embodiment of the present invention.

Figures 2A and 2B show perspective views of a membraneless battery microcell according to a specific embodiment of the present invention.

Figure 3A-C shows a cross-sectional view of the membrane-free battery microcell of Figure 2 along line A-A, including different types of electrodes.

Figure 4A shows a diagram of a battery microreactor according to a specific embodiment of the present invention.

Figure 4B shows a cross-sectional view of the battery microreactor of Figure 4A along line B-B, including the stack of membrane-free battery microcells of Figure 2.

Figure 5 shows a perspective view of a redox microfluidic energy storage system without an electrolyte tank according to a specific embodiment of the present invention.

Figure 6 shows a diagram of the redox microfluidic energy storage system of Figure 5.

Figure 7 shows a block diagram of a battery management system according to a specific embodiment of the present invention.

Figure 8 shows a flowchart of a charging method for the redox microfluidic energy storage system of Figure 1 according to a specific embodiment of the present invention.

Figure 9 shows a flowchart of the discharge method of the redox microfluidic energy storage system of Figure 1 according to a specific embodiment of the present invention.

Detailed Implementation

Figure 1 shows a block diagram of a redox microfluidic energy storage system 100 according to a specific embodiment of the present invention. It should be understood that the storage system 100 of Figure 1 may include additional components, and some components described herein may be removed and/or modified without departing from the scope of the storage system 100. Furthermore, the implementation of the storage system 100 is not limited to this embodiment.

The redox microfluidic energy storage system 100 includes a battery reactor 101, a positive electrolyte tank 102 for storing a positive liquid electrolyte, a negative electrolyte tank 103 for storing a negative electrolyte, a battery management system 104, and a flow circulation system formed by a first micropumping system 105, a second micropumping system 106, and a microfluidic conduit 107, which respectively fluidly connects the positive electrolyte tank 102 and the negative electrolyte tank 103 to the first micropumping system 105 and the second micropumping system 106. The flow circulation system also includes a microfluidic conduit 108 that fluidly connects the first micropumping system 105 and the second micropumping system 106 to the battery reactor 101. In such embodiments, the first micropumping system 105 and the second micropumping system 106 may further include microvalves (not shown) arranged in the microfluidic conduits of the micropumping systems 105 and 106 and at the outlet of the battery reactor 101 to regulate the electrolyte flow rate. The battery reactor 101 further includes a plurality of membrane-free battery microcells 109, which are connected in parallel and fluidly connected to each other and to a first micropumping system 105 and a second micropumping system 106.

A first micro-pumping system 105 is configured to supply positive electrode liquid electrolyte from positive electrode electrolyte tank 102 to membrane-free battery microcell 109, and a second micro-pumping system 106 is configured to supply negative electrode liquid electrolyte from negative electrode electrolyte tank 103 to membrane-free battery microcell 109. These first and second micro-pumping systems 105 and 106 are independent of each other, such that the positive electrode liquid electrolyte and the negative electrode liquid electrolyte are in contact only within the respective battery microcell 109.

The battery management system 104 is configured to manage actuators, including fluid pumping or injection systems and flow regulation systems, such as micropumps or microvalves in a flow circulation system, to supply liquid electrolyte to the membrane-free battery microcell 109 at a desired flow rate to maintain a laminar flow state of the electrolyte within the battery reactor 101, thereby enabling the redox microfluidic energy storage system 100 to be charged or discharged. This desired electrolyte flow rate can be between 0 and 1000 μl per minute to ensure such a laminar flow state.

At least a portion of the battery reactor 101, positive electrode electrolyte tank 102, negative electrode electrolyte tank 103, battery management system 104, first micro-pumping system 105, second micro-pumping system 106, microfluidic conduit 108, and microfluidic conduit 107 are integrated into the same body or module 110. This solution is more compact, simple, and easy to operate.

Figures 2A and 2B show two perspective views of a membraneless battery microcell 200 according to a specific embodiment of the present invention. It should be understood that the membraneless battery microcell 200 of Figures 2A and 2B may include additional components, and some components described herein may be removed and/or modified without departing from the scope of the membraneless battery microcell 200. Furthermore, embodiments of the membraneless battery microcell 200 are not limited to such embodiments.

The membrane-free battery microcell 200 includes a positive electrode semi-microcell 201 housing a positive electrode 202 and a negative electrode semi-microcell 203 housing a negative electrode 204. Electrodes 202 and 204 are “forest-like” electrodes formed from multiple carbon microtubes or nanotubes. Different types of electrodes made of other materials can also be used, as long as they can effectively carry out the desired redox reaction. Each semi-microcell 201, 203 is T-shaped and fluidly connected to its opposite T-shaped semi-microcell 201, 203, thereby forming a reaction microchannel 205 therebetween. Positive and negative liquid electrolytes flow parallel to each other in a laminar flow manner through the reaction microchannel 205, and electrolyte interdiffusion is generally limited to the interface width at the center of the reaction microchannel 205. The specific geometry of the membrane-free battery microcell 200 maximizes the available space for electrodes 202 and 204, allowing for larger electrodes. This reduces the diffusion time for ion charge carrier exchange within the electrolyte and increases the energy transfer rate, while minimizing the resistance to ion charge carrier diffusion from one electrolyte to another. Furthermore, this specific geometry facilitates its stacking.

The arrows indicate the flow direction of each of the two electrolytes flowing through the membraneless battery microcell 200. Although arrows 206 and 207 are shown in the same direction, the electrolytes may flow in opposite directions. Furthermore, the flow rates of each of the positive and negative liquid electrolytes supplied to the battery microcell 200 may be substantially the same or may be different.

Although the embodiments of Figures 2A and 2B illustrate membrane-free battery microcells with specific geometries and electrode types, other membrane-free battery microcells with different geometries and electrode types can be implemented in the redox microfluidic energy storage system of the present invention.

Figure 3A-C shows a cross-sectional view of the membrane-free battery microcell 200 in Figure 2 along line A-A, including different types of electrodes 202 and 204.

Figure 3A includes planar electrodes 202 and 204 attached to the inner surfaces of the long cross sections of the positive electrode semi-micro unit 201 and the negative electrode semi-micro unit 203, respectively.

Figure 3B shows forest-shaped electrodes 202 and 204 attached to the inner surfaces of the long cross-sections of the positive electrode semi-micro unit 201 and the negative electrode semi-micro unit 203, respectively. The forest-shaped electrodes may be forest-shaped carbon nanotube electrodes or similar electrodes.

Figure 3C shows porous electrodes 202 and 204 that are essentially space-filling, defined by the long cross-sections of the positive electrode semi-micro unit 201 and the negative electrode semi-micro unit 203. Forest-type electrodes and porous electrodes have larger active surfaces than planar electrodes, and therefore exhibit higher efficiency and better performance.

In some other embodiments of the invention, other types of electrodes with different arrangements can be used within the semi-micro unit. For example, the electrodes can be combined with fins or any other protrusions having a geometry extending from the main plane containing the electrodes.

In all cases, the positive electrode liquid electrolyte 206 and the negative electrode liquid electrolyte 207 fill the corresponding positive electrode semi-micro units 201 and negative electrode semi-micro units 203, forming an interphase 208 therebetween for transferring ionic charge carriers between the liquid electrolytes 206 and 207. Only molecular diffusion of ionic charge carriers participates in the mixing of the positive electrode liquid electrolyte 206 and the negative electrode liquid electrolyte 207.

Electrodes 202 and 204 can be made of carbon materials, transition metal oxides (such as TiO2, SnO2, Co3O4, NiO, Fe2O3, V2O5, Cu2O, MnO2 and GeO2), transition metal dichalcogenides (such as MoS2 and WS2), elements (such as Si, Ge and Au), intercalation compounds (such as Li4Ti5O12, LiCoO2, LiMn2O4, LiFePO4) and conductive polymers (polypyrrole and polyaniline).

Preferably, electrodes 202 and 204 are carbon-based electrodes with porous structures to facilitate the flow of electrolytes 206 and 207 through the pores of electrodes 202 and 204. More preferably, the electrodes may have conductive structures to improve the conduction of current generated during system discharge or supplied during system charging. Furthermore, the porosity of the electrodes is preferably uniform to facilitate a uniform distribution of current flowing through the electrodes. Alternatively, the electrodes may exhibit a porosity gradient to optimize current distribution in the porous electrodes and optimize the performance of the battery microcells.

When electrodes 202 and 204 have a porous structure, the porous materials for electrodes 202 and 204 may include fibrous carbon, porous metals, felt, activated carbon, silica, gels, foams, sponges, ceramics, filters, meshes, polymers, and metal-organic structures, etc. Furthermore, the porosity of electrodes 202 and 204 is preferably high, allowing the pore size to be in the range of approximately 1 to 120 micrometers. The porous materials may also have a high total active surface area exposed to the electrolyte flow to improve their efficiency and performance.

An electrolyte is a mixture of electroactive chemical elements or redox substances and a solvent with minor components to improve the performance of the fluid as a charge carrier, thereby increasing its conductivity. By selecting a suitable electrolyte, the nominal voltage of a redox microfluidic energy storage system can be modified. In other words, the voltage difference between the positive and negative electrodes of a battery microcell will depend on the electrolyte used, typically between 0.5 and 1.6 V when the solvent is water-based.

Generally, any aqueous or non-aqueous electrolyte can be used, where aqueous electrolytes are solutions of acids, bases, or salts in water, and non-aqueous electrolytes can be solutions of salts in organic solvents or ionic liquids. Similarly, redox substances can be organic or inorganic. It is equally important that these electrolytes be compatible with each other to avoid poisoning in the event of mixing or leakage from any conduit in the flow circulation system.

Organic redox substances can be any organic redox substance capable of undergoing reversible redox reactions and maintaining its solubility in electrolytes when its oxidation state changes. Therefore, it is desirable that organic redox substances do not decompose or degrade and do not form solid or gaseous substances. These organic redox substances include quinones, etc. Inorganic redox substances can be selected from metals and oxide metals, such as Fe, Cu, Co, Cr, V, Ni, Mn, Ru, U, etc.

Figure 4A shows an apparatus diagram of a battery microreactor 300 according to a specific embodiment of the present invention. It should be understood that the battery microreactor 300 of Figure 4A may include additional components, and some components described herein may be removed and/or modified without departing from the scope of the battery microreactor 300. Furthermore, the implementation of the battery microreactor 300 is not limited to such embodiments. Figure 4B shows a cross-sectional view of the battery microreactor of Figure 4A along line B-B, illustrating a stack of membrane-free battery microcells of Figures 2 and 3.

The battery microreactor 300 includes a first inlet 301 for introducing a positive electrode liquid electrolyte into a positive electrode semi-microcell 202, a first outlet 302 for discharging the positive electrode liquid electrolyte, a second inlet 303 for introducing a negative electrode liquid electrolyte into a negative electrode semi-microcell 203, and a second outlet 304 for discharging the negative electrode liquid electrolyte. Notably, the first inlet 301, the first outlet 302, and the microconduit 305 through which the positive electrode liquid electrolyte flows are independent of the second inlet 303, the second outlet 304, and the microconduit 306 through which the negative electrode liquid electrolyte flows. The two electrolytes 206 and 207 are in contact with each other only within the reaction microchannel 205 of the membrane-free battery microcell 200.

Since Figure 4A shows a diagram of the battery microreactor 300, most of the microconduits through which the negative electrode liquid electrolyte flows (except for the portion 306 in the microcircuit directly connected to the second inlet 303 and the second outlet 304) are located below the microconduit 305, through which the positive electrode liquid electrolyte flows. Furthermore, as seen in Figure 4B, the stack of membrane-free battery microcells 307 comprises two membrane-free battery microcells 307 per column and thirty-two membrane-free battery microcells per row. The solid positive electrode fluid electrolyte 206 and negative electrode fluid electrolyte 207, which enter the battery microreactor 300 via the first inlet 301 and the second inlet 303, flow through the positive electrode half-microcell 201 and the negative electrode half-microcell 203 of each membrane-free battery microcell 200 as shown in Figures 2 and 3, respectively.

The main body of the battery microreactor 300 is a solid component, through which the inlet, outlet, microconduct, and membrane-free battery micro-unit all pass.

Although Figures 4A and 4B show specific geometries and arrangements of the inlet, outlet, and microducts of the battery microreactor, the battery microreactor can have different geometries, layouts, and designs. Furthermore, the battery microreactor can contain different numbers of membrane-free battery microcells of varying shapes and geometries.

Figure 5 shows a perspective view of a redox microfluidic energy storage system 400 without an electrolyte tank according to a specific embodiment of the present invention. It should be understood that the storage system 400 of Figure 5 may include additional components, and some components described herein may be removed and/or modified without departing from the scope of the storage system 400. Furthermore, the implementation of the storage system 400 is not limited to this embodiment.

The redox microfluidic energy storage system 400 includes a battery reactor 401, a first micropump 402, a first inlet flow meter 403, a first outlet flow meter 404, a first microvalve 405, a first micro compressor 406 for actuating the first microvalve 405, a second micropump 407, a second inlet flow meter 408, a second outlet flow meter 409, a second microvalve 410, and a second micro compressor 411 for actuating the second microvalve 410.

In such embodiments, although the first micropump 402 and the second micropump 407, the battery reactor 401, and the first microvalve 405 and the second microvalve 410 are integrated within the body 412 or the microchip, the remaining referenced components of the redox microfluidic energy storage system 400 shown in FIG. 5 are fluidly coupled to the body 412.

A first micropump 402 is fluidly connected to a first inlet 413 of the body 412. The first inlet 413 is also fluidly connected to an outlet of a positive electrolyte tank (not shown), from which positive liquid electrolyte is recovered. The first micropump 402 generates a vacuum to draw positive liquid electrolyte from the positive electrolyte tank via a microconduit 414 and pumps it to the battery microcell 401 at a desired flow rate via a microconduit 415. A first inlet flowmeter 403, disposed in the microconduit 415, continuously monitors the flow rate of the positive liquid electrolyte flowing through the microconduit 415, enabling the battery management system (not shown) to instruct the first micropump 402 to adjust its pumping power to maintain the flow rate within a predefined margin.

Similarly, a second micropump 407 is connected to a second inlet 416 of the body 412 and is configured to retrieve negative electrode liquid electrolyte from a negative electrode storage tank (not shown) via a microconduit 417 and pump it to the battery microcell 401 at a desired flow rate via a microconduit 418. A second inlet flow meter 408 disposed in the microconduit 418 continuously monitors the flow rate of the negative electrode liquid electrolyte flowing through the microconduit 418, enabling the battery management system to instruct the second micropump 407 to adjust its pumping power to maintain the flow rate within a predefined margin. Depending on various factors, the flow rates of the positive and negative electrode liquid electrolytes may be similar or different.

The positive electrode liquid electrolyte flows out of the battery reactor 401 through a microconduit 419 toward a first microvalve 405. A first outlet flow meter 404, arranged in the microconduit 419, continuously monitors the flow rate of the positive electrode liquid electrolyte flowing through the microconduit 419, enabling the battery management system to instruct a first microcompressor 406 to modify the channel of the first microvalve 405 to ensure that the flow rate within the battery reactor 401 is within a predefined margin, which guarantees a laminar flow state of the electrolyte and keeps the electrolyte phases centrally located, minimizing cross-mixing. The outlet of the first microvalve 405 is fluidly connected to a first outlet 421 of the body 412 via a microconduit 420. The first outlet 421 connects the fluid to the inlet of the positive electrode electrolyte tank. The redox microfluidic energy storage system 400 also includes an electrochemical sensor (not shown in the figure), which may be located within the tank or microconduit, to measure the amount of ionic charge carriers and redox active material in each electrolyte to derive the viscosity of each electrolyte and the state of charge of the redox microfluidic energy storage system.

Similarly, the negative electrode liquid electrolyte flows out of the battery reactor 401 through microconduit 422 toward the second microvalve 410. A second outlet flow meter 409, arranged in microconduit 422, continuously monitors the flow rate of the negative electrode liquid electrolyte flowing through microconduit 422, enabling the battery management system to instruct the second microcompressor 411 to modify the channel of the second microvalve 410 to ensure that the flow rate within the battery reactor 401 is within a predefined margin, which guarantees laminar flow of the electrolyte and keeps the interphase phases of the electrolytes centrally located, minimizing cross-mixing. The outlet of the second microvalve 410 is fluidly connected to the second outlet 424 of the body 412 via microconduit 423. The second outlet 424 connects the fluid to the inlet of the negative electrode electrolyte tank. Based on the calculated viscosity difference between the electrolytes, the battery management system instructs the microcompressors 406, 411 to modify the channels of microvalve 405, 410 to balance the interphase phases within the battery reactor 401.

The electrodes of the battery reactor 401 are electrically connected to corresponding conductive strips 425a-b, through which current is supplied from an external source during charging of the redox microfluidic energy storage system, or through which current generated during discharging of the redox microfluidic energy storage system is supplied to external devices. Conductive strip 425a may be electrically connected to the positive electrode 202, and conductive strip 425b may be electrically connected to the negative electrode 204, or vice versa.

In such embodiments, microcatheters 414, 415, 417, 418, 419, 420, 422, and 423 are also integrated within the body 412. Microcompressors 406, 411, micropumps 402, 407, and flow meters 403, 404, 408, and 409 include electrical and electronic connectors that connect to the power and battery management system to receive power and operating commands.

Figure 6 shows an apparatus diagram of the redox microfluidic energy storage system of Figure 5. The battery reactor 401 comprises a stack of battery microcells connected in parallel with each other. In this embodiment, only the positive electrode half-cell is shown. The negative electrode half-cell is located directly below the positive electrode half-cell. While the positive electrode half-cell is fluidly connected to the microconduits 415, 419 through which the positive electrode liquid electrolyte flows, the negative electrode half-cell is fluidly connected to the microconduits 418, 422 through which the negative electrode liquid electrolyte flows. The positive electrode liquid electrolyte flows at the same flow rate through all positive electrode half-cells. The negative electrode liquid electrolyte flows at the same flow rate through all negative electrode half-cells. However, the flow rates of the positive and negative electrode liquid electrodes through the battery reactor may be substantially the same or different.

Figure 7 shows a block diagram of a battery management system 500 according to a specific embodiment of the present invention. It should be understood that the battery management system 500 of Figure 7 may include additional components, and some components described herein may be removed and/or modified without departing from the scope of the battery management system 500. Furthermore, the implementation of the battery management system 500 is not limited to this embodiment.

As shown in Figure 1, the battery management system 500 is responsible for determining whether, given a request to store a certain amount of energy or a request to deliver a certain amount of power, the required power can be released in the redox microfluidic energy storage system with available energy, or whether the given required energy can be stored within the current storage capacity of the redox microfluidic energy storage system. The battery management system 500 is also responsible for managing the flow circulation system to ensure that operating conditions are suitable for providing the required power or storing the required energy. To achieve these objectives, the decision-making structure of the battery management system 500 interacts with the actuator 501 and sensor 502 of the redox microfluidic energy storage system. The battery management system 500 then operates as follows:

A request is provided by a user or external device as the initial input to the power management unit 503. This request may be a power demand for transferring a specific amount of energy to a power-consuming device through the redox microfluidic energy storage system, or it may be a power demand for storing energy in the redox microfluidic energy storage system.

The input is first evaluated by the power management unit 503, which receives information about the state of charge (SOC) of the redox microfluidic energy storage system from sensors. The power management unit 503 initially makes a rough decision about whether there is a possible stoichiometric flow rate setpoint (stoichiometric Q setpoint) where the required power can be released or received, and calculates the value of this stoichiometric flow rate setpoint. To monitor the SOC, the redox microfluidic energy storage system may include electrochemical sensors in contact with two electrolytes to determine the electrochemical potential difference between them. The decision regarding the existence of a possible stoichiometric flow rate setpoint and the corresponding power availability or storage capacity in the redox microfluidic energy storage system can be sent by the power management unit to the electronic management system (EMS), which communicates with the user or any external device receiving the request and notifies them of the existing power availability and storage capacity via the appropriate interphase.

If a stoichiometric flow rate setpoint that meets the power requirement exists, this information is passed to the interphase management unit 504. Given the total stoichiometric flow rate setpoint and variables from sensor 502 (such as electrolyte temperature (T) and SOC), the interphase management unit 504 can define the correct configuration of the battery microreactor with an intermediate phase by selecting the individual flow rates (required Qi) at each inlet and outlet of the battery microreactor. This configuration minimizes cross-effects between electrolytes and allows for stable battery operation.

Once the individual flow rates at each inlet and outlet of the battery microreactor are defined for operation, they are fed to a fluid management unit 505, which calculates specific actuator parameters that define how actuators 501 (e.g., micropumps and microvalves in a redox microfluidic energy storage system) should work with information (current Qi) received from flow meters 502 that monitor the flow rates at the inlet and outlet of the battery microreactor to reach these setpoints defined by the individual flow rates at each inlet and outlet of the microreactor.

If these individual flow rate setpoints are achieved and operation is possible, the final step of the battery management system 500 is to verify the power/storage capacity availability of the power management system for battery operation. The power management unit uses information about whether these individual flow rate setpoints have been reached to verify that the power capacity is available, and that the stoichiometric flow rate is not only present but also satisfied, and that the remaining battery operating conditions are correct.

Figure 8 shows a flowchart of a charging method 600 for the redox microfluidic energy storage system 100 of Figure 1 according to a specific embodiment of the present invention.

The general reversible reaction that occurs in the battery microcell after the electrolyte passes through can be described as follows:

These are the charging and discharging reactions located at the negative and positive electrodes, respectively. The charging process involves applying a specific current as the electrolyte flows through the battery microreactor 101. Micropumping systems 105 and 106 allow the electrolyte to flow in a laminar flow state through the electrode structures within the reaction microchannels of the membrane-free battery microcell 109, while simultaneously applying current to these electrodes to induce a charging redox reaction on the electrode surfaces, thereby achieving the battery charging process. The flow rate regulation of pumping systems 105 and 106 will also depend on the specific applied current. The higher the applied current, the higher the flow rate of the electrolyte through the battery reactor 101. The state of charge of the battery is monitored and controlled by open-circuit voltage measurement or by various technologies using various sensors involving the characteristics of the electrolyte. The charge is stored in the electrolyte, which is then returned to tanks 102 and 103 and repeatedly circulated through the battery reactor 101 until the desired state of charge is achieved in the bulk.

Method 600 includes the following steps:

The first micro-pumping system 105 supplies 601 positive electrode liquid electrolyte to the positive electrode half-micro cell of the battery micro cell 109;

The second micro-pumping system 106 simultaneously supplies 602 negative electrode liquid electrolyte to the negative electrode half-micro cell of the battery micro cell 109;

A current of 603 is applied to the positive and negative electrodes of the battery microcell 109, while the positive and negative liquid electrolytes simultaneously flow through the positive and negative electrode semi-microcells in a laminar flow manner, respectively. This causes the redox reaction of the active material in the electrolyte to occur at the electrode surface, and ionic charge carriers transfer between the two electrolytes to compensate for the change in oxidation state of the active material, thereby generating a chemical potential difference between the positive and negative electrode liquid electrolytes; and

The positive electrode liquid electrolyte and the negative electrode liquid electrolyte are stored in the positive electrode electrolyte tank 102 and the negative electrode electrolyte tank 103, respectively, at 604.

Figure 9 shows a flowchart of the discharge method 700 of the redox microfluidic energy storage system of Figure 1 according to a specific embodiment of the present invention.

When the energy stored in the redox microfluidic energy storage system 100 needs to be discharged, the electrolyte flows back into the battery reactor 101, undergoing a reverse reaction relative to the charging process, and the electrodes generate current to release the energy to the outside. For this purpose, the battery management system utilizes information from sensors that monitor the state of charge of the electrolyte, at least via open-circuit voltage or through various technologies involving the electrolyte's characteristics. Furthermore, the battery management system controls the amount of energy released during the discharge process by adjusting the flow rate within the battery reactor 101 to achieve a specific current or specific performance of the redox microfluidic energy storage system 100. The electrolyte flows repeatedly between tanks 102 and 103 and the battery microreactor 101 until the desired state of discharge is achieved in the bulk.

Because of the mixing of substances between electrolytes, the products of diffusion processes, and the absence of physical barriers within the microreactor, a rebalancing process may be necessary after multiple charge-discharge cycles. This rebalancing process may be required depending on tracking of microflow battery capacity changes or any other value providing evidence of the presence of substances in the counterflow. The rebalancing process may involve applying current to both electrolytes such that their resulting state of charge is nearly zero. For example, some regeneration systems (such as rebalancing units) can be used to reduce electrolyte imbalance.

Method 700 includes the following steps:

The first micro-pumping system 105 supplies 701 positive electrode liquid electrolyte to the positive electrode half-micro cell of the battery micro cell 109, and there is a chemical potential difference between the positive electrode liquid electrolyte and the negative electrode liquid electrolyte.

Simultaneously, the second micro-pumping system 106 supplies 702 negative electrode liquid electrolyte to the negative electrode semi-micro-cell of the battery micro-cell 109, causing the redox reaction of the active material in the electrolyte to occur at the electrode surface, and ionic charge carriers to transfer between the two electrolytes to compensate for the change in the oxidation state of the active material, releasing the current circulating through the electrodes of the positive and negative electrode semi-micro-cells; and

The positive electrode liquid electrolyte and the negative electrode liquid electrolyte are stored in the positive electrode electrolyte tank 102 and the negative electrode electrolyte tank 103, respectively, 703.

Claims (15)

1. A redox microfluidic energy storage system (100), comprising a battery reactor (101), a positive electrode electrolyte tank (102) for storing a positive electrode liquid electrolyte, a negative electrode electrolyte tank (103) for storing a negative electrode liquid electrolyte, a battery management system (104), and a flow circulation system. The battery reactor (101) comprises a plurality of membrane-free battery micro-units (109) connected to each other. Each battery micro-unit (109) includes a positive electrode semi-micro-unit (201) accommodating a positive electrode (202) and a negative electrode semi-micro-unit (203) accommodating a negative electrode (204). The positive electrode semi-micro-unit (201) and the negative electrode semi-micro-unit (203) are fluidly connected and positioned relative to each other. The flow circulation system includes: a first micro-pumping system (105) configured to supply the positive electrode liquid electrolyte from the positive electrode electrolyte tank (102) to the positive electrode semi-micro unit (201); and a second micro-pumping system (106) configured to supply the negative electrode liquid electrolyte from the negative electrode electrolyte tank (103) to the negative electrode semi-micro unit (203). The redox microfluidic energy storage system (100) is characterized in that the first micropumping system (105) and the second micropumping system (106) are configured to supply the positive electrode liquid electrolyte and the negative electrode liquid electrolyte respectively, with flow rates such that the positive electrode liquid electrolyte and the negative electrode liquid electrolyte are in a laminar flow state inside the battery microcell (109), the positive electrode liquid electrolyte and the negative electrode liquid electrolyte are in direct contact inside the membrane-free battery microcell (109), and an interphase is formed therebetween for transferring ionic charge carriers between the liquid electrolytes. The battery management system (104) is configured to supply the liquid electrolyte to the battery reactor (101) via the flow circulation system and simultaneously supply current through the electrodes (202, 204) to charge the redox microfluidic energy storage system (100) or to supply the liquid electrolyte to the battery reactor (101) via the flow circulation system such that current is released through the electrodes (202, 204) to discharge the redox microfluidic energy storage system (100). 2. The redox microfluidic energy storage system (100) according to claim 1, wherein the battery management system (104) is configured to adjust the electrolyte flow rate within the battery reactor (101) based on at least one of the current state of charge of the redox microfluidic energy storage system (100), the current value circulating through the electrodes (202, 204), and the power transmitted by the redox microfluidic energy storage system (100) or the power received from an external source. 3. The redox microfluidic energy storage system (100) according to claim 1 or 2, wherein the battery management system (500) comprises: A power management unit (503) is configured to receive a request to cause the redox microfluidic energy storage system (100) to deliver a specific amount of power to a power-consuming device, or to cause the redox microfluidic energy storage system (100) to store energy with a specific amount of power, determine whether a stoichiometric flow rate setpoint in the redox microfluidic energy storage system (100) is feasible to deliver the required amount of power or to store energy with the required amount of power, and calculate the stoichiometric flow rate setpoint. An interphase management unit (504) is configured to determine the corresponding flow rates of the positive and negative electrode liquid electrolytes at the inlet (301, 303) and outlet (302, 304) of the battery reactor (101) based on the calculated stoichiometric flow rate setpoint; and A fluid management unit (505) is configured to determine the operating mode of the flow circulation system such that the determined flow rate is achieved at the inlet (301, 303) and outlet (302, 304) of the battery reactor (101). 4. A redox microfluidic energy storage system (100) according to any one of the preceding claims, wherein the positive electrode half-microcell (201) and the negative electrode half-microcell (203) of each membrane-free battery microcell (200) define a reaction microchannel (205) therebetween, wherein the positive electrode liquid electrolyte and the negative electrode liquid electrolyte flow parallel through the reaction microchannel (205) in a laminar flow manner. 5. A redox microfluidic energy storage system (100) according to any one of the preceding claims, comprising flow regulating devices (405, 410) in a microfluidic conduit of the flow circulation system disposed between the outlet of the battery reactor (401) and the corresponding tank, the flow regulating devices (405, 410) being configured to regulate the flow rate of the liquid electrolytes flowing out of the battery reactor (401) based on the viscosity difference between two liquid electrolytes, preferably by adjusting the channel of the microfluidic conduit to balance the interphase between the two within the battery reactor (101). 6. The redox microfluidic energy storage system (100) according to claim 5, wherein the flow regulating device (405, 410) includes at least one microvalve selected between a piezoelectric microvalve and a pneumatic microvalve, and wherein the pneumatic microvalve is preferably actuated by a pneumatic compressor. 7. The redox microfluidic energy storage system (100) according to any one of the preceding claims, wherein the flow rates of the positive electrode liquid electrolyte and the negative electrode liquid electrolyte within the membrane-free battery microcell (109) are selected from the range of 0 to 1000 μl per minute. 8. A redox microfluidic energy storage system (100) according to any one of the preceding claims, comprising a first inlet flow sensor (403) and a first outlet flow sensor (404) disposed in corresponding microfluidic conduits (415, 419) of the first micropumping system, and a second inlet flow sensor (408) and a second outlet flow sensor (409) disposed in corresponding microfluidic conduits (418, 422) of the second micropumping system, wherein the first inlet flow sensor (403) and the second inlet flow sensor (408) are configured to measure the flow rates of the positive and negative electrolytes at the inlet of the battery reactor (401), respectively, and the first outlet flow sensor (404) and the second outlet flow sensor (409) are configured to measure the flow rates of the positive and negative electrolytes at the outlet of the battery reactor (401), respectively. 9. The redox microfluidic energy storage system (100) according to any one of the preceding claims, wherein the battery reactor (101) and the flow circulation system are integrated into the same body (110). 10. A charging method (600) for a redox microfluidic energy storage system (100) according to any one of claims 1 to 9, characterized in that it comprises: The first micro-pumping system (105) supplies (601) the positive electrode liquid electrolyte to the positive electrode half-micro-unit (201) of the membrane-free battery micro-unit (109); The second micro-pumping system (106) simultaneously supplies (602) the negative electrode liquid electrolyte to the negative electrode semi-micro-unit (203) of the membrane-free battery micro-unit (109); A current (603) is applied to the positive electrode (202) and the negative electrode (204) of the membrane-free battery microcell (109), while the positive and negative liquid electrolytes simultaneously flow in laminar flow through the positive electrode semi-microcell (201) and the negative electrode semi-microcell (203), respectively. This causes redox reactions of the active substances in the electrolytes to occur on the surfaces of the electrodes (202, 204), and ionic charge carriers to transfer between the two electrolytes to compensate for changes in the oxidation state of the active substances, thereby generating a chemical potential difference between the positive and negative electrode liquid electrolytes; and The positive electrode liquid electrolyte and the negative electrode liquid electrolyte are stored in the positive electrode electrolyte tank (102) and the negative electrode electrolyte tank (103), respectively. 11. The charging method (600) of the redox microfluidic energy storage system (100) according to claim 10, comprising: The power management unit (503) of the battery management system (500) receives a request to store energy in the redox microfluidic energy storage system (100) with a specific amount of power. The power management unit (503) determines whether a stoichiometric flow rate setpoint capable of storing energy at the required power level is feasible. The power management unit (503) calculates the stoichiometric flow rate setpoint; The interphase management unit (504) of the battery management system (500) determines the flow rates of the positive and negative electrode liquid electrolytes at the inlet and outlet of the battery reactor (101) based on the calculated stoichiometric flow rate setpoint; and The operating mode of the flow circulation system is determined by the fluid management unit (505) of the battery management system (500) so that the determined flow rates are achieved at the inlet and outlet of the battery reactor (101). 12. A charging method (600) for the redox microfluidic energy storage system (100) according to claim 10 or 11, comprising: The state of charge of the redox microfluidic energy storage system (100) is monitored by the battery management system (500); and Perform the steps of claim 10 or 11 until the maximum energy capacity in the redox microfluidic energy storage system (100) has been reached and/or the power request for storing energy has been completed. 13. The discharge method (700) of the redox microfluidic energy storage system (100) according to any one of claims 1 to 9, characterized in that it comprises: The first micro-pumping system (105) supplies (701) the positive electrode liquid electrolyte to the positive electrode half-micro-unit (201) of the membrane-free battery micro-unit (109), and there is a chemical potential difference between the positive electrode liquid electrolyte and the negative electrode liquid electrolyte; Simultaneously, the second micro-pumping system (106) supplies (702) the negative electrode liquid electrolyte to the negative electrode semi-micro-unit (203) of the membrane-free battery micro-unit (109), causing the redox reaction of the active material in the electrolyte to occur on the surface of the electrodes (202, 204), and ionic charge carriers to transfer between the two electrolytes to compensate for the change in the oxidation state of the active material, releasing the current circulating through the electrodes (202, 204) of the positive and negative electrode semi-micro-units (201, 203); and The positive electrode liquid electrolyte and the negative electrode liquid electrolyte are stored (703) in the positive electrode electrolyte tank (102) and the negative electrode electrolyte tank (103), respectively. 14. The discharge method (700) of the redox microfluidic energy storage system (100) according to claim 13, comprising: The power management unit (503) of the battery management system (500) receives a request from the redox microfluidic energy storage system (100) to transfer energy in a specific amount of power. The power management unit (503) determines whether a stoichiometric flow rate setpoint capable of transmitting the required power is feasible. The power management unit (503) calculates the stoichiometric flow rate setpoint; The interphase management unit (504) of the battery management system (500) determines the flow rates of the positive and negative electrode liquid electrolytes at the inlet and outlet of the battery reactor (101) based on the calculated stoichiometric flow rate setpoint; and The operating mode of the flow circulation system is determined by the fluid management unit (505) of the battery management system (500) so that the determined flow rates are achieved at the inlet and outlet of the battery reactor (101). 15. The discharge method (700) of the redox microfluidic energy storage system (100) according to claim 13 or 14, comprising: The state of charge of the redox microfluidic energy storage system (100) is monitored by the battery management system (500); and Perform the steps of claim 13 or 14 until the minimum energy capacity in the redox microfluidic energy storage system (100) has been reached and/or the power request for energy transfer has been completed.