CN110571877B - Bendable wireless charging device - Google Patents

Abstract

A bendable wireless charging device having an operable bend radius of approximately 90 degrees includes a flexible substrate, a receiving coil, a battery, a flexible EMI shielding layer, and a control module. The receiving coil is arranged on one surface of the substrate and is electrically connected to the control module. The battery, which may be a flexible battery, is disposed below the other surface of the substrate. An EMI shielding layer is disposed between the receiving coil and the battery.

Description

A bendable wireless charging device

Technical field

The present invention relates to electronic charging devices, and in particular to a wireless charging device having an operable bending radius of approximately 90 degrees in use.

Background technique

Recently, with the development of non-contact (i.e., wireless) charging technology, portable electronic devices have adopted inductive wireless charging devices for wireless charging. Wireless power transmission can be defined as resonant wireless power transmission through magnetic induction between a coil located in a power transmitting unit (PTU) and a coil located in a power receiving unit (PRU); the PRU then transmits the received power to batteries for various types of portable electronic devices.

Wearable electronics, in particular, require thin and lightweight batteries to keep the wearer comfortable and safe. As wearable electronics take on more complex shapes, they require batteries that can bend or stretch with the wearer's body. While some flexible batteries have been disclosed, these tend to have various rigid or brittle components, such as ceramic separators, that limit how much the battery can bend. The integration of the PRU itself with the aforementioned flexible battery is also considered another challenge; as the receiving coil is usually formed from thick metal wires that are not easily bent.

Therefore, it has become a challenge for battery manufacturers to integrate PRUs and flexible batteries into flexible charging devices. There is an urgent need for a bendable wireless charging device and a flexible battery; such a device and battery can be used in bendable electronic devices, such as portable wearable electronic devices.

Contents of the invention

It is an object of the present invention to provide a wireless charging device that addresses the above and other needs. According to one aspect of the present invention, a flexible wireless charging device is provided that integrates a battery, especially a flexible battery.

According to an embodiment of the present invention, a flexible wireless charging device includes a flexible substrate, a flexible receiving coil, a battery, a flexible EMI shielding layer, and a control module. The base plate has an operational bending radius of approximately 90 degrees. The receiving coil is arranged on a surface of the substrate. The battery is located under the other surface of the base plate. The EMI shielding layer is provided between the receiving coil provided on the substrate and the battery. The control module is arranged or formed on a side of the substrate adjacent to the receiving coil, and is electrically connected to the receiving coil and the battery respectively.

According to another aspect of the present invention, the flexible wireless charging device further includes an additional output connection group connected to an external load so that the flexible battery can simultaneously perform a wireless charging process and a discharging process on the external load. The control module controls the charging process of the flexible battery and/or the discharging process of the load.

Description of the drawings

The accompanying drawings illustrate the invention by way of illustration and not limitation. In the drawings, the same or similar reference numbers represent the same or similar elements, where:

Figure 1 schematically shows a flexible wireless charging device according to an embodiment of the present invention;

Figure 2 shows an example of a flexible wireless charging device according to an embodiment of the present invention;

Figure 3 shows an example of a cross-sectional view of a bendable wireless charging device without a battery;

Figure 4 shows an example of actual implementation of a bendable wireless charging device according to an embodiment of the present invention;

Figure 5 schematically shows a control module according to an embodiment of the present invention;

Figure 6 schematically shows a flexible wireless charging device according to another embodiment of the present invention;

Figure 7 shows an example of a bendable wireless charging device according to the embodiment shown in Figure 6;

Figure 8 schematically illustrates a bendable wireless charging device according to the embodiment shown in Figure 6;

Figure 9 depicts a flexible battery structure that can be used in the bendable wireless charging device shown in Figure 1;

Figure 10 depicts a Jellyroll battery structure that can be used in the flexible wireless charging device shown in Figure 1; and

11A and 11B respectively depict the structures of the sponge diaphragm of the present invention and the corresponding previous example.

Detailed ways

In the following description, various flexible batteries and flexible wireless charging devices are exemplified. It will be apparent to those skilled in the art that modifications, including additions and/or substitutions, may be made without departing from the scope and spirit of the invention. Specific details may be omitted to avoid obscuring the invention; however, the specification is written to enable those skilled in the art to practice the teachings herein without undue experimentation.

Referring to FIGS. 1 and 2 , FIG. 1 is a schematic diagram of a flexible wireless charging device according to an embodiment of the present invention; FIG. 2 is an example diagram showing a flexible wireless charging device according to an embodiment of the present invention. In this embodiment, the flexible wireless charging device 10 includes a flexible substrate 100 , a substantially planar receiving coil 20 , a flexible battery 40 , a flexible EMI shielding (electromagnetic interference shielding) layer 102 , and a control module 30 . The substrate 100 has an operable bend radius of at least 90 degrees. The term "operable bend radius" means that the charging device can be bent to at least 90 degrees and still be electronically and mechanically functional. Furthermore, it may be possible to bend it up to 120 degrees or 180 degrees (with the halves overlapping each other) and still function normally. The receiving coil 20 is disposed on the surface of the substrate 100 and is used to receive electric energy from the external transmission inductor coil 11 . This external transmission inductor is typically connected to a power source, such as a traditional wall outlet, or to a computer power supply via a USB port. It should be noted that the battery 40 may be a flexible battery, and the relevant details will be described later. Alternatively, it can be a very small battery, such as a button battery or a thin film battery. The small size allows the charging device to be conductive and bent without being disturbed. The flexible battery 40 is located below another surface of the substrate 100 which may also be provided with the receiving coil 20 . EMI shielding layer 102 is provided between receiving coil 20 and flexible battery 40 . The control module 30 is provided or formed on a side of the substrate 100 adjacent to the receiving coil 20 and is electrically connected to the receiving coil 20 and the flexible battery 40 respectively.

The control module 30 may also include a first output connection set 300 formed with two electrodes 302 , 304 (eg, conductive pads) representing the positive and negative terminals of the respective flexible battery 40 .

In addition, referring to FIG. 3 , FIG. 3 is an example diagram showing a cross-sectional view of the bendable wireless charging device without a flexible battery. The receiving coil 20 is composed of a metal layer 202 fabricated on the flexible substrate 100 using an additive or subtractive coating method and at least one covering layer 204 attached to the metal layer 202 . The material of the metal layer 202 may be copper, silver, copper alloy, silver composite material or a combination thereof. At least one cover layer 204 protects the metal layer 202 from mechanical damage or oxidation, and may also include an optional adhesive layer (not shown) over the metal layer 202 with the cover layer 204 positioned over the optional adhesive layer. layer. The materials of the substrate 100 and the cover layer 204 may be polyimide (PI) sheets, polyetheretherketone (PEEK), transparent conductive polyester film, elastomer film, polyethylene terephthalate (PET) or its combination.

The thickness of the metal layer 202 is in the range of 5-100 μm, and the thickness of the substrate 100 or the cover layer 204 is in the range of 2-100 μm.

The EMI shielding layer 102 may be formed of an electromagnetic wave absorbing material or an electromagnetic wave reflecting material (such as a thermoplastic or elastomeric material or a combination thereof) and a conductive metal film or powder or fiber filler (such as a metal/carbon powder or fiber). Exemplary EMI shielding materials include copper and nickel coated polyurethane sheets, silicone rubber with embedded magnetic ferrite particles.

Referring to FIG. 4 , FIG. 4 shows an example diagram of an implementation of a wireless charging device according to an embodiment of the present invention. In this embodiment, the wireless charging device is mounted on the outer surface of a helmet. As shown in FIG. 4 , the wireless charging device 10 is bent into an arc shape along the outline of the helmet 50 .

The receiving coil of the bendable wireless device according to the present invention can withstand at least 2000 repeated bending (bending radius between 20-40 mm and bending angle of at least 120 degrees) without loss of charging performance.

Refer to Figures 1, 2 and 5. Figure 5 is a schematic diagram of a control module according to an embodiment of the present invention. In this embodiment, the control module 30 includes a wireless charging circuit 300, a battery charging circuit 320 and a protection circuit 340 connected in series.

The wireless charging circuit 300 is electrically connected to the receiving coil 20 . The battery charging circuit 320 regulates the voltage and current from the wireless charging circuit 300 and outputs the regulated voltage and current to the protection circuit 340 .

The protection circuit is connected to the flexible battery through the first output connection group, and further includes a switch module 360 connected between the protection circuit and the flexible battery. Protection circuits are used to sense and control switch modules. When the current or voltage input from the battery charging circuit exceeds or falls below a predetermined value, the switch module turns OFF, thus avoiding incorrect charging of the flexible battery. The predetermined value may be defined as a threshold value including corresponding scenarios such as short circuit, overcharge, and undercharge. Those skilled in the art will recognize that the predetermined value may be varied based on the desired use or type of flexible battery. For example, the overvoltage range measured between the first set of output connections may be selected to be 3.5 volts to 5 volts, and the undervoltage range may be selected to be 2 volts to 3 volts.

Refer to Figures 6 to 8. Fig. 6 is a schematic diagram of a bendable wireless charging device according to another embodiment of the present invention; Fig. 7 is an example diagram showing a bendable wireless charging device according to the embodiment shown in Fig. 6; Fig. 8 is a diagram illustrating a bendable wireless charging device according to the embodiment shown in Fig. 6 Schematic diagram of the control module. This embodiment is similar to the embodiment shown in Figure 1 . The difference is that the control module of the embodiment shown in Figure 6 also includes: a second output connection group 310 and a switch module 361, where the second output connection group 310 is electrically connected to an external load, system or electronic device (hereinafter Referred to as "load 60"), switch module 361 consists of a series cascade of charge switches and discharge switches.

In this embodiment, as shown in FIGS. 6 and 7 , the control module 30 is located on a side of the substrate 100 adjacent to the receiving coil 20 and is electrically connected to the receiving coil 20 , the flexible battery 40 and the load 60 for controlling the flexible The charging process of the battery 40 and/or the discharging process to the load 60 . Flexible battery 40 is located beneath EMI shielding layer 102 . Load 60 is not shown in Figure 7, but it can be considered to be any type of battery-powered electronic device, such as a cordless electric toothbrush, a watch, or glasses. Those skilled in the art will realize that the implementation and configuration of wireless charging of these devices may be different, since the bendable wireless charging device of the present invention will usually be disposed in corresponding devices using its flexible capabilities.

As shown in FIG. 8 , the switch module 361 includes a charging switch 362 and a discharging switch 363 . In this embodiment, each of the charge switch 362 and the discharge switch 363 may be an N-type MOSFET (Metal Oxide-Semiconductor Field Effect Transistor). Each MOSFET has a gate, a drain and a source. The gates of the charging switch 362 and the discharging switch 363 are respectively connected to the protection circuit 340. The drains of the charge switch 362 and the discharge switch 363 are connected to each other. The source of charge switch 362 is connected to the negative terminal of load 60 . The source of discharge switch 363 is connected to the negative terminal of flexible battery 40 . The positive terminals of flexible battery 40 and load 60 are connected to a common node.

The battery charging circuit 320 regulates the voltage and current from the wireless charging circuit 300 and outputs the adjusted voltage and current to the protection circuit 340 through VBAT shown in FIG. 8 . Protection circuit 340 will continuously monitor flexible battery 40 and load 60 by detecting the voltage and/or current status of flexible battery 40 and load 60 .

As described in the above paragraphs, the protection circuit 340 includes a plurality of predetermined values for determining whether the bendable wireless charging device of the present invention operates normally. When the voltage detected during charging or discharging is higher or lower than a certain predetermined value, the protection circuit 340 will selectively reduce the voltage on the gate of the charging switch 362 during the charging process or selectively reduce the voltage on the gate of the charging switch 362 during the discharging process. The voltage on the gate of discharge switch 363 is reduced. Since the gate voltage is low, the charge switch 362 and the discharge switch 363 will be switched OFF, so the protection circuit 340 will be in an open state due to the large resistance of the OFF MOSET type switch.

In contrast, for traditional wireless charging devices without an additional (i.e. second) output connection set, the corresponding external load or electronic device can still connect to the battery and draw power from the battery. The advantage of having the second output connection group connected to the protection circuit of the control module is that the wireless charging device of the present invention can not only prevent the battery from being damaged by overcharging or over-discharging during the charging and discharging process, but also can wirelessly charge the battery. , and discharge to the load at the same time; thus, the practicability and convenience of the present invention are enhanced.

9 schematically illustrates a cross-section of a portion of a flexible foldable lithium-ion battery according to one aspect of the present disclosure, which can be used as the battery 40 used in the bendable wireless charging device of the present invention. Cell 40 has an operating bend radius of 180 degrees. As used herein, the term "operating bend radius" refers to the degree to which a battery can be bent to still produce power without causing interruption in operation. An operating bend radius of 180 degrees means the battery can fold completely onto itself while still producing power.

In FIG. 9 , element 5 represents a single cell of a battery including a first current collector 521 , a second current collector 531 , and a separator 51 . The first current collector 521 may be selected from metals such as aluminum. The aluminum may be a sheet having a thickness of about 5 microns to about 100 microns. Active material 522 may be coated on one or both sides of the aluminum sheet to form the cathode. The active material may be selected from, for example, LiCoO2, LiMn2O4, Li2MnO3, LiNiMnCoO2, LiNiCoAlO2, LiFePO4 or LiNi0.5Mn1.5O4, but other active materials and mixtures thereof may also be used.

The second current collector can be selected from metals such as copper. The copper may be a sheet having a thickness of about 5 microns to about 100 microns. Active material 532 may be coated on one or both sides of the copper sheet to form an anode. Active materials used in anodes include carbon-based active materials such as graphite, carbon nanotubes, graphene, silicon, silicon/carbon composites, germanium, tin, metal oxides, metal hydrides, and mixtures thereof.

The separator 51 is located between the current collectors to prevent the current collectors from contacting each other. The separator 51 is a highly porous and highly elastic polymer fiber felt sponge. The resilience of the sponge is sufficient to maintain the separation of the current collectors 521 and 531 regardless of whether the battery is bent, folded, cut, or penetrated by foreign objects. The term "sponge" as used herein refers to a porous, absorbent, and elastic structure that retains fluid while maintaining resilience. The sponge returns to its original shape after deformation. That is, as long as the external force is maintained, the sponge can be squeezed into a smaller area; once the external force is removed, the sponge returns to its original shape and volume. The separator acts as a sponge, firmly holding liquid electrolyte, but when the battery case is punctured or cut, the separator also maintains sufficient absorptive capacity to keep the liquid electrolyte in a leak-free state, preventing harmful electrolytes from escaping. Furthermore, the resilience of the sponge septum enables the electrodes to return to their proper separated positions after mechanical damage (e.g., cutting and puncture), thereby imparting self-healing properties to the overall structure. The term "self-recovery" as used herein refers to a battery structure that can return to its original configuration after mechanical damage such that power continues to be produced after a power outage caused by mechanical damage. The sponge separator can return to its original shape and volume due to its spongy properties, allowing the entire battery structure to self-heal.

The electrolyte used in the battery may include one or more organic solvents, such as one or more of ethylene carbonate, dimethyl carbonate, and diethyl carbonate. Dissolved in the solvent is one or more lithium salts, such as LiPF6, LiBF4 or LiClO4. The composition of the electrolyte is usually adjusted based on the active materials selected for the cathode and anode.

Although FIG. 9 shows the battery cells of a battery based on a component stack structure, layers of components can be formed and rolled into a so-called "core" structure, as shown in FIG. 10 . In Figure 10, a separator layer 51 is located not only between the cathode and anode of each "cell" layer, but also between adjacent cell layers to prevent short circuits between the electrodes, thereby creating a self-healing overall flexible And has a resilient structure.

Sponge membranes can be formed from a mat of sub-micron fibers. In one aspect, the fibers can have a diameter between approximately 100 nm and 300 nm. The porosity can be from about 60% to about 90%, with an average pore size of less than about 1 micron. Specifically, submicron fibers can be made of polymers such as polyvinylidene fluoride (PVDF), polyimide (PI), polyamide (PA), polyacrylonitrile (PAN), polyethylene terephthalate Made of (PET), poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), (vinylidene fluoride-chlorotrifluoroethylene) copolymer (PVDF-co-CTFE) or their mixtures.

In another embodiment, the sponge membrane may be a nonwoven polymeric fiber mat, wherein the polymeric fibers are a composite of a first polymeric material and a second polymeric material. The first polymer material may include poly(vinylidene fluoride) (PVDF), polyimide (PI), polyamide (PA), or polyacrylonitrile (PAN). The second polymer material may include polyethylene glycol (PEG), polyacrylonitrile (PAN), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-hexafluoride) Fluoropropylene) (PVDF-HFP) or (vinylidene fluoride-chlorotrifluoroethylene) copolymer (PVDF-co-CTFE), wherein the second polymer material is different from the first polymer material. The weight ratio of the first and second polymeric materials may range from about 3:1 to about 1:1, more specifically from about 3:1 to about 2:1, more specifically from about 3:1 to about 3:2 Within, and more specifically about 3:1.

PVDF is widely used in the manufacture of ultrafiltration membranes and microfiltration membranes due to its excellent chemical resistance and good thermal stability. Pure PVDF polymer has a high melting point and crystallinity, and has good mechanical properties. However, it is only soluble in a limited variety of solvents, such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF ), dimethyl sulfoxide (DMSO), and show low swelling capacity when soaked in ordinary electrolytes.

PVDF-HFP copolymers can improve electrolyte solubility, making the polymer soluble in common organic solvents such as acetone and tetrahydrofuran (THF), which can further improve processing capabilities. In addition, it has a very high swelling capacity, which can enhance the electrolyte absorption of the separator layer.

The inventors of the present application have found that composite materials of PVDF and PVDF-HFP provide many advantages over other polymers in manufacturing separators, such as: electrochemical stability from 0V to 5V relative to Li+/Li; Better solubility of pure PVDF, which enhances processability; faster electrolyte wettability than PVDF; better control of electrolyte leakage; durable bonding to electrodes; and good flexibility.

The composite material can be formed into a nonwoven fiber mat by electrospinning, described in further detail below. Electrospinning can be done from polymer formulations onto aluminum foil to obtain self-standing separators. The polymeric formulation may include the first and second polymeric materials in a total amount of about 15-25%, preferably about 15-20%, more preferably about 16.5% by weight of the formulation. The polymer formulation used for electrospinning to obtain a sponge separator may further comprise about 1-5% by weight, preferably about 2-5% by weight, more preferably about 3-5% by weight, and most preferably about 5% by weight of at least one additive. . The additive may be lithium chloride (LiCl) to facilitate ion transfer across the membrane and facilitate the electrospinning process by increasing the conductivity of the polymer solution. In a preferred embodiment, the polymer formulation may contain about 0.1-0.6 μg, preferably about 0.1-0.5 μg, more preferably about 0.2-0.4 μg, most preferably about 0.3-0.4 μg of LiCl.

In another embodiment, in conjunction with any of the foregoing and following embodiments, the polymer formulation used for electrospinning to obtain the nonwoven nanofibrous membrane of the present application may include at least one solvent selected from the group consisting of: N-methyl- 2-Pyrrolidone (NMP), N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetone and tetrahydrofuran (THF). In a preferred embodiment, the polymer formulation may include DMF and acetone. In another preferred embodiment, the polymer formulation may include a weight ratio of from about 3:1 to about 1:1, preferably from about 2:1 to about 1:1, more preferably from about 1.5:1 to 1:1, and most preferably from about 1.5:1 to 1:1. Approximately 1.25:1 DMF to acetone is preferred.

In another embodiment, in conjunction with any of the above and below embodiments, the nonwoven nanofibrous membrane of the present application can be electrospun by adding the first and second polymeric materials to at least one solvent, optionally Add together with LiCl; heat and stir the resulting mixture at about 80-100°C for about 2-5 hours; optionally add at least one additive, and then heat at about 80-100°C for about 2-5 hours; the polymer The formulation solution was cooled to room temperature; and the polymer formulation solution was loaded into a carriage for electrospinning.

The electrospinning of the sponge membrane of the present application can be carried out under the following parameters: temperature: about 20-30°C; voltage: about 20-50kV; relative humidity (RH): about 25-60%; spinner height: 100- 150mm; feeding rate: 5.5-8.5ml/h.

On the other hand, additives for tetramethyl orthosilicate (TMOS) or tetraethylorthosilicate (TEOS) can be used with polymer formulations. These additives can hydrolyze into ceramic components, thereby improving the surface texture of the sponge separator and increasing dimensional stability.

The microstructure of an exemplary sponge membrane is shown in Figure 11A; as shown in Figure 11A, individual fibers are easily distinguished and many pores are formed, with a porosity of approximately 80%. In comparison, the microstructure of a prior art commercial separator (Celgard 2400 polypropylene separator) with approximately 40% porosity is shown in Figure 11B. In this lower porosity structure, individual fibers are not easily distinguished. The individually interconnected fibers in the sponge of Figure 11A create a flexible and resilient sponge separator that contributes to the self-healing characteristics of the batteries of various embodiments.

While the application has been described in terms of various embodiments and implementations thereof, the application is not limited thereto but covers various obvious modifications and equivalent arrangements falling within the scope of the appended claims. Although features of the application are presented in certain combinations between the claims, it is contemplated that these features may be provided in any combination and order.

Claims (15)

1. A bendable wireless charging device, including: A flexible substrate having an operable bending radius of at least 90 degrees; a substantially planar receiving coil for receiving electrical energy from an external transmission inductor coil and disposed on a surface of the flexible substrate; Flexible batteries with an operable bending radius of at least 90 degrees; A flexible EMI shielding layer located between the receiving coil and the flexible battery for blocking electromagnetic interference from the receiving coil; A control module located or formed on one side of the flexible substrate adjacent to the receiving coil and electrically connected to the receiving coil, an external load and the battery, wherein the control module is used to control the The charging process of the flexible battery and the discharging process of the load; The control module further includes a first output connection group and a second output connection group, wherein the control module is connected to the flexible battery through the first output connection group, and is connected to the flexible battery through the second output connection group. the external load. 2. The device of claim 1, wherein the control module further includes a wireless charging circuit, a battery charging circuit and a protection circuit connected in series, wherein the wireless charging circuit is connected to the receiving coil, and the protection circuit A switch module is connected between the circuit and the flexible battery. 3. The device of claim 2, wherein the switch module includes a charging switch and a discharging switch connected in series. 4. The device of claim 3, wherein the protection circuit is selectively turned on during charging by comparing a predetermined value with the voltage and/or current of the flexible battery or the load. and turn off the charging switch, or selectively turn on and off the discharging switch during the discharging process. 5. The device of claim 3, wherein the charging switch and the discharging switch are MOSFET devices having a gate, a drain and a source, The gate of the charging switch and the gate of the discharging switch are respectively connected to the protection circuit; The drain of the charging switch and the drain of the discharging switch are connected to each other; The source of the charging switch is connected to the negative terminal of the load; The source of the discharge switch is connected to the negative terminal of the flexible battery, and the positive terminal of the flexible battery and the positive terminal of the load are connected to a common node. 6. The device of claim 1, wherein the flexible battery is a lithium-ion battery. 7. The device of claim 6, wherein the lithium-ion battery includes an electrospun polymer fiber sponge separator. 8. The device of claim 7, wherein the lithium-ion battery is a self-restoring lithium-ion battery. 9. The device of claim 1, wherein the receiving coil consists of a metal layer and at least one covering layer attached to the metal layer, wherein the metal layer is formed by additive or subtractive coating. Manufactured on the flexible substrate. 10. The device of claim 9, wherein the metal layer is selected from the group consisting of copper, silver, copper alloys, and silver composite materials. 11. The device of claim 9, wherein the at least one covering layer protects the metal layer from mechanical damage or oxidation. 12. The device of claim 9, wherein the receiving coil further includes an adhesive layer over the metal layer, and the covering layer is over the adhesive layer. 13. The device of claim 9, wherein the flexible substrate and the cover layer are made of materials including polyimide (PI) sheets, polyetheretherketone (PEEK), transparent conductive polyester films, Elastomeric film, polyethylene terephthalate (PET), or combinations thereof. 14. The device of claim 9, wherein the metal layer has a thickness in the range of approximately 5-100 μm, and the flexible substrate and the cover layer have a thickness in the range of approximately 2-100 μm. 15. The device of claim 1, wherein the flexible EMI shielding layer is selected from metal-coated polymers or polymers with embedded conductive particles or fibers, polyurethane sheets, embedded magnetic ferrite Silicone rubber, polyester, elastomer and combinations of solid particles.