CN112803028A - Ultrafast-charging manganese-zinc battery - Google Patents

Abstract

The invention relates to a manganese-zinc battery with ultra-fast charging function. It includes a positive electrode, a negative electrode material zinc, and an electrolyte. The positive electrode is a material that can be used as a current collector, and there is no positive active material on the positive electrode. The electrolyte is an electrolyte containing divalent zinc and divalent manganese. It adopts a high-voltage deposition charging method to achieve fast charging and high energy storage capacity of manganese-zinc batteries. As an aqueous battery with high energy and practical prospects, it is expected to be commercialized in the future.

Description

An ultra-fast charging manganese-zinc battery

technical field

The invention relates to the field of aqueous secondary batteries, in particular to an ultra-fast charging manganese-zinc battery.

Background technique

In the future, energy and environment will become two major problems facing mankind. The depletion of traditional coal, oil and other primary energy sources and the increasingly prominent environmental pollution have challenged the survival and development of human beings. In this context, clean, economical and renewable energy has received extensive attention from scientists. New energy is often instantaneous and not durable, so energy storage is particularly important. Energy storage has been widely used in power grids, electric vehicles and various electronic devices. Today, the most commonly used energy storage device is the lithium-ion battery. However, in the long run, the shortage of lithium resources and the environmental and safety issues brought about during production and use will limit the long-term development of lithium-ion batteries in the future. In contrast, water-based batteries have the advantages of safety, non-toxicity and low price, so they have received increasing attention from scientific and engineering workers. In particular, zinc-ion batteries, the current study found to have higher energy than most other types of aqueous batteries. Among them, the manganese-zinc battery is one of the most representative zinc-ion batteries, especially with the discovery of the two-electron transfer mechanism of manganese (Angew Chem Int Ed 2019, 58, 7823-7828.), so that its capacity can exceed 600mAh /g, the energy density can reach 1000Wh/Kg (calculated by the mass of manganese material). The energy density of the entire device is expected to reach the standard of lithium batteries. However, in practical applications, how to realize low-cost, high-reliability and high-capacity manganese-zinc batteries is still a difficult problem. In addition, the ultra-fast charging of manganese-zinc batteries is still a blank in scientific research and engineering research in the industry. Achieving ultra-fast charging is undoubtedly a very meaningful performance for batteries, which will help promote the prospect of manganese-zinc batteries in the field of energy storage, especially in energy storage batteries required for electric vehicles. The ultra-fast charging of manganese-zinc batteries will greatly shorten the charging time of energy storage devices such as electric vehicles and electronic devices, providing technical support for further commercialization.

SUMMARY OF THE INVENTION

Based on the above background, the present invention proposes a manganese-zinc battery with ultra-fast charging function.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

A manganese-zinc battery with ultra-fast charging function is provided, comprising a positive electrode, a negative electrode material zinc, and an electrolyte, wherein the positive electrode is a material that can be used as a current collector, and there is no positive active material on the positive electrode, and the electrolyte is composed of two Electrolyte of zinc and manganese.

According to the above scheme, the materials that can be used as current collectors are selected from conductive materials such as carbon and inert metals, such as carbon cloth, carbon felt, carbon paper and titanium materials.

According to the above scheme, the negative electrode material zinc is commercial zinc flakes with a thickness of 0.01 mm or more.

According to the above scheme, the zinc salt solution includes zinc-containing salt solutions such as zinc sulfate, zinc nitrate and zinc acetate; the manganese salt solution includes manganese-containing salt solutions such as manganese sulfate, manganese nitrate and manganese acetate.

According to the above scheme, the molar ratio of divalent manganese and divalent zinc in the electrolyte is preferably in the range of 1:2 to 4:1; It is beneficial to increase the capacity, but the amount of electrolyte is large, and it can be adjusted according to the needs when using.

According to the above scheme, the charging method of the above manganese-zinc battery is constant voltage charging, and the applied voltage ranges from 2V to 2.6V. Below 2V, the deposition of manganese cannot be achieved, and above 2.6V, the battery discharge efficiency will be lower due to water splitting.

According to the above scheme, the manganese-zinc battery assembly method can adopt the battery assembly form of the prior art such as winding core, lead-like battery and soft pack battery.

According to the above scheme, the manganese-zinc battery with ultra-fast charging function also includes a battery separator, and the battery separator can be a separator for an aqueous battery or a separator for a supercapacitor in the prior art, such as fiber paper, non-woven fabric, polypropylene Diaphragm and fiberglass, etc. If it can be ensured that the positive and negative electrodes in the device do not contact each other, the separator may not be used.

The charging method of the manganese-zinc battery with ultra-fast charging function is to perform constant voltage charging on the battery, and achieve the effect of fast charging through constant voltage deposition, and the applied voltage range is 2V-2.6V. Below 2 V, the deposition of manganese cannot be achieved, and above 2.6 V, the battery discharge efficiency is low due to water splitting.

The invention provides a manganese-zinc battery with ultra-fast charging and high capacity. The positive electrode is a material that can be used as a current collector, there is no positive active material on the positive electrode, the negative electrode material is zinc, and the electrolyte is an electrolyte containing divalent zinc and divalent manganese. During the charging process, the manganese salt can be rapidly converted into manganese dioxide and deposited on the positive electrode current collector; during the discharging process, the manganese dioxide is dissolved in the electrolyte again. It adopts a high-voltage deposition charging method to achieve fast charging and high energy storage capacity of manganese-zinc batteries. Therefore, the manganese-zinc battery designed by the present invention through the "precipitation-dissolution" principle of manganese has fast charging speed, high capacity and low cost. As an aqueous battery with high energy and practical prospects, it is expected to be commercialized in the future. .

The specific working principle is shown in Figure 1. A certain constant voltage is applied to the battery. When this voltage is greater than the theoretical deposition voltage of manganese (about 2V), the divalent manganese ions in the solution will be deposited on the positive electrode current collector such as carbon cloth. Solid manganese dioxide is formed on the surface, at this time, the negative electrode zinc ions are reduced to zinc; then during the discharge process, the solid manganese dioxide is redissolved into the solution, and the zinc is oxidized to zinc ions, thus forming a cycle. During this process, the rapid deposition of manganese achieves the goal of ultrafast charging due to the higher voltage. In addition, the conversion between divalent manganese ions and manganese dioxide is a two-electron reaction, and the combination of current collectors such as carbon cloth that can carry high manganese dioxide loadings is also beneficial to achieve higher battery capacity.

The beneficial effects of the present invention are:

1. The positive electrode of the manganese-zinc battery provided by the present invention has no positive active material, and only uses a current collector as the deposition substrate of the positive ions in the solution. The structure is simple, and ultra-fast charging can be achieved, and the battery only undergoes repeated precipitation-dissolution reactions on the surface of the positive electrode current collector during the charging and discharging process, and will not cause damage to the material, so its stability is also good.

2. The electrochemical reaction (conversion between divalent manganese ions and manganese dioxide) that occurs in the battery provided by the present invention belongs to a two-electron transfer reaction, and a current collector such as carbon cloth that can carry a high load of manganese dioxide is also matched. It facilitates the realization of high-capacity manganese-zinc batteries and provides a basis for future commercial applications.

Description of drawings

Figure 1. Design principle of high-capacity ultrafast charging manganese-zinc batteries.

Figure 2 (a) charge-discharge test of Mn-Zn battery, (b) and (c) SEM images of carbon cloth before and after the reaction of Mn-Zn battery.

Figure 3 (a) XRD characterization of the positive electrode before and after the reaction, (b) energy spectrum XPS characterization of the positive electrode before and after the reaction.

Figure 4 shows the discharge capacity for different charging times at 2.2V.

Figure 5 shows a 2.2V charge cycle test for 5 minutes.

Figure 6. Other capacity and efficiency plots for different charging voltages and times.

Detailed ways

Example 1

In this embodiment, the positive electrode current collector is carbon cloth, the negative electrode is 0.1mm zinc sheet, and the electrolyte is a mixed solution of 1M zinc sulfate and manganese sulfate, respectively, to assemble a zinc-manganese battery. As shown in Figure 2, different from the traditional constant current charging method, the zinc-manganese battery adopts the constant voltage charging method. The charging voltages in Figure 2a are 2V, 2.2V, 2.4V and 2.6V, respectively. It can be seen that after 5 minutes of constant voltage charging, when the discharge current is 1mA/ ^cm2 , it shows different discharge times at different voltages, and it can reach about 180 minutes at 2.6V, which is the discharge time in constant current charging and discharging. is nearly 40 times higher, indicating that the manganese-zinc battery of the present invention has the advantage of ultra-fast charging by using constant voltage deposition. It is worth noting that when the voltage is just 2V, the discharge voltage platform is only displayed at about 1.3V, and when the voltage is higher than 2V, a new discharge platform will appear at about 1.8V. This is because according to theoretical speculation, the reaction of realizing two electron transfer requires a voltage above 2V. Therefore, in practice, the voltage of constant voltage deposition needs to be greater than 2V to realize the high-capacity chemical reaction of manganese-zinc batteries. Figures b and c are the electron microscope SEM images of the carbon cloth on the positive electrode substrate before and after the reaction (that is, before and after charging), respectively. It can be seen that a layer of solid is deposited on the surface of the carbon cloth after charging; after discharging, this layer of solid is obviously dissolved.

Figure 3 shows the X-ray diffraction (XRD) and energy spectrum (XPS) characterization of the material on the carbon cloth before and after the reaction. The results show that the solid deposited after charging is manganese dioxide, and the amount of manganese dioxide decreases sharply after discharging. . Combined with the above SEM image results, it can be explained that the divalent manganese ions in the solution are converted into solid manganese dioxide during the charging process; during the discharge process, the solid manganese dioxide is dissolved into the solution and converted into divalent manganese ions. This fully demonstrates the feasibility of the design of the invention.

Figure 4 shows the capacity diagram for different charging times under the condition of 2.2V. As the charging time continues to increase from 5 minutes to 120 minutes, the capacity also increases. The highest capacity can reach nearly 10mAh/cm ² .

Figure 5 shows the charge-discharge cycle performance test under the condition of 2.2V charging for 5 minutes. When the discharge current reaches 10mA/ ^cm2 , the number of cycles can reach 1800 times, which greatly exceeds the basic requirement of 500 cycles for commercial use. The good stability of the manganese-zinc battery at high discharge speed shows that the battery can not only be charged ultra-fast, but also has a fast discharge speed, that is, the output power is large, which will have a good application in many fields, especially in the field of electric vehicles prospect.

Figure 6 shows the capacity and coulombic efficiency of the battery at different voltages and different charging times. As the charging voltage and charging time continue to increase, the capacity also increases. However, under the same voltage, the longer the charging time is, the lower the coulombic efficiency is, which means that too long charging time will lead to the occurrence of water splitting, thereby reducing the coulombic efficiency of energy storage. In addition, it can be noticed that the capacity of charging for 1 hour and 2 hours under the condition of 2.6V is basically the same, about 21mAh/ ^cm2 , indicating that the capacity of this manganese-zinc battery has a corresponding limit with the increase of manganese dioxide deposition. . Therefore, in practical applications, choosing the appropriate voltage and charging time can make the capacity and coulombic efficiency reach the optimum situation.

Claims (10)

1. A manganese-zinc battery with an ultrafast charging function is characterized in that: the electrolyte is an electrolyte containing divalent zinc and divalent manganese.

2. The manganese-zinc battery with ultra-fast charging function according to claim 1, characterized in that: the material capable of being used as the current collector is carbon and inert metal conductive material.

3. The manganese-zinc battery with ultra-fast charging function according to claim 1, characterized in that: the material capable of being used as the current collector comprises carbon cloth, carbon felt, carbon paper and titanium metal material.

4. The manganese-zinc battery with ultra-fast charging function according to claim 1, characterized in that: the material zinc which can be used as the current collector is a commercial zinc sheet with the thickness of more than 0.01 mm.

5. The manganese-zinc battery with ultra-fast charging function according to claim 1, characterized in that: the zinc salt solution used as the material of the current collector comprises zinc sulfate, zinc nitrate, zinc acetate and other zinc-containing salt solutions; the manganese salt solution comprises manganese sulfate, manganese nitrate, manganese acetate and other manganese salt solutions.

6. The manganese-zinc battery with ultra-fast charging function according to claim 1, characterized in that: the manganese-zinc battery can be used as a current collector and is charged in a constant voltage manner, and the applied voltage range is 2-2.6V.

7. The manganese-zinc battery with ultra-fast charging function according to claim 1, wherein: the manganese-zinc battery assembly mode can adopt the battery assembly modes of a roll core, a similar lead storage battery, a soft package battery and the like in the prior art.

8. The manganese-zinc battery with ultra-fast charging function according to claim 1, characterized in that: the manganese-zinc battery with the ultra-fast charging function also comprises a battery diaphragm.

9. The manganese-zinc battery having an ultra-fast charging function according to claim 8, wherein: the battery diaphragm adopts a diaphragm for a water-based battery or a super capacitor diaphragm selected from fiber paper, non-woven fabric, a polypropylene diaphragm and glass fiber.

10. The method for charging a manganese-zinc battery having an ultrafast charging function according to claim 1, wherein: the battery is charged with constant voltage, and the applied voltage range is 2V-2.6V.

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