Lithium peroxide preparation device and preparation method

Abstract

The invention discloses a lithium peroxide preparation device and a lithium peroxide preparation method, and belongs to the technical field of lithium ion batteries. The lithium peroxide preparation device provided by the invention is a liquid flow Li-O2 battery for decoupling electrolyte, and the positive electrode side structure is divided into an electrochemical reaction module and a solid product generation module, so that the problem that a solid product is deposited on a porous electrode and is difficult to separate is solved, and efficient and continuous batch production of Li2O2 can be realized; and decoupling the positive electrode side electrolyte by using an external fluid flow field, taking the generated solid product out of a battery system under the action of the flow field, and storing to obtain high-purity Li2O2 as an efficient lithium ion battery lithium supplement agent.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and particularly relates to a lithium peroxide preparation device and a preparation method thereof. Background Art

[0002] Currently, in order to match the energy performance requirements of high-tech electronic devices, it is necessary to develop lithium-ion battery technologies with high capacity, high energy density, and long cycle life. However, similar high-capacity anode materials often face a sharp problem, that is, under a large volume expansion effect, the reduction decomposition reaction of the electrolyte at the anode interface will lead to a relatively high first-capacity loss, manifested as a low first Coulombic efficiency. For example, the first Coulombic efficiency of traditional graphite materials is only 90%, and that of silicon-based anodes is as low as 50 - 60%. In addition, during the cycling process of lithium-ion batteries, the continuous consumption and repair of the SEI film, as well as the gradual increase of dead lithium inside the positive and negative electrodes, cause the battery capacity to continuously decay and the cycle life to decrease accordingly.

[0003] To effectively solve the problem of battery capacity reduction caused by irreversible capacity during the first charge-discharge and cycling operation of the battery, currently, the method of adding a part of active lithium inside the lithium-ion battery is generally adopted to alleviate the capacity loss and extend the battery service life. The current lithium supplementation technologies mainly include anode lithium supplementation, cathode lithium supplementation, separator lithium supplementation, and electrolyte lithium supplementation, etc. The lithium supplementation technology is mainly realized through lithium supplementation additives, which can release Li + so as to play a role in lithium supplementation. Lithium peroxide (Li2O2), as an easily decomposable lithium-rich compound, is a very promising lithium supplementation additive (Energy Storage Science and Technology, 2021, 10(3): 800 - 812). It is reported that lithium peroxide with many defect sites has higher ionic conductivity, low crystallinity, and the ionic conductivity can reach 2×10 -8 mS / cm. Compared with highly crystalline lithium peroxide (4×10 -18 mS / cm), the ionic conductivity is ten orders of magnitude higher (Chem. Rev. 2020, 120, 6558 - 6625). However, commercial Li2O2 has few surface defect sites, low ionic conductivity, and high crystallinity. When doped in electrode materials, it will significantly reduce the ion transport rate and the lithium supplementation efficiency. How to batch-prepare Li2O2 with high lithium supplementation efficiency is an urgent problem to be solved.

[0004] During the discharge process of a lithium-oxygen (Li-O2) battery, oxygen acts as a reactant and can deposit high-purity Li2O2 rich in defect sites on the cathode side. However, the following problems are encountered during the production of Li2O2: First, the solid product deposits on the electrode surface and is difficult to separate; second, the deposition of Li2O2 is considered the main reason for the premature failure of the Li-O2 battery, making it difficult to continuously produce Li2O2. Therefore, achieving the efficient separation and continuous production of the solid product Li2O2 is of great significance for high-efficiency lithium supplement agents for lithium-ion batteries. Summary of the Invention

[0005] The purpose of the present invention is to provide a lithium peroxide preparation device and a preparation method. The lithium peroxide preparation device provided by the present invention is a liquid-flow Li-O2 battery with decoupled electrolytes. By dividing the positive electrode side structure into two modules: an electrochemical reaction module and a solid product generation module, the problem of difficult separation of solid products deposited on the porous electrode is solved, and the efficient and continuous batch production of Li2O2 can be achieved; then, an external fluid flow field is used to decouple the electrolyte on the positive electrode side, and the generated solid product is carried out of the battery system under the action of the flow field and stored to obtain high-purity Li2O2 as an efficient lithium supplement agent for lithium-ion batteries (since it is prepared by an electrochemical method, it has low crystallinity and high conductivity).

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] One of the technical solutions of the present invention: Provide a lithium peroxide preparation device. On the basis of a traditional lithium-oxygen battery, the chamber containing the electrolyte on the positive electrode side is divided into electrolysis chamber A, a solid electrolyte membrane, and electrolysis chamber B; wherein, electrolysis chamber A is located on the positive electrode material side, and electrolysis chamber B is located on the separator side; electrolysis chamber A is used to load electrolyte A without Li + and electrolysis chamber B is used to load electrolyte B containing Li + , and the solid electrolyte membrane is used to isolate the electrolyte A without Li + from the electrolyte B containing Li + ; a fluid outlet and a fluid inlet are provided on electrolysis chamber B, and the fluid outlet and the fluid inlet are connected to an external fluid pump to form a fluid flow field; a solid recovery and separation module is provided between the fluid outlet and the external fluid pump for separating the prepared lithium peroxide.

[0008] The liquid-flow Li-O2 battery with decoupled electrolytes provided by the present invention can be divided into an electrochemical reaction zone and a solid product Li2O2 generation zone during the discharge process. The electrochemical reaction zone is the positive electrode and is infiltrated with an electrolyte without Li + , and only oxygen reduction occurs in this region to generate superoxide radicals (O 2- ); the solid product Li2O2 generation zone is a cavity, and the inside is rich in Li+ electrolyte in this region O 2- reacts with Li + to form Li2O2. The electrochemical reaction zone and the solid product formation zone are separated by a solid electrolyte membrane. A fluid pump and a solid product recovery and separation tank are designed externally. During the reaction, due to the action of the fluid pump, the electrolyte in the cavity will carry the generated Li2O2 out of the reaction system and into the solid product recovery tank. Through the post-treatment process, a pure Li2O2 solid product can be obtained.

[0009] In the present invention, the material of the solid electrolyte membrane can be selected from lithium germanium aluminum phosphate (LAGP), lithium titanium aluminum phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), etc.

[0010] Preferably, the positive electrode material is a porous electrode.

[0011] The porous electrode can ensure the stability of the oxygen transport path. At the same time, the high specific surface area and abundant catalytic active sites contribute to the rapid progress of the electrochemical reaction.

[0012] Preferably, an electrolyte storage module is provided between the fluid inlet and the external fluid pump.

[0013] The second technical solution of the present invention: provides a method for preparing lithium peroxide based on the above lithium peroxide preparation device, including the following steps: during discharge, peroxide ions are generated on the positive electrode material, and the peroxide ions pass through the electrolyte A containing no Li + in the electrolytic chamber A and penetrate through the solid electrolyte membrane into the electrolyte B containing Li + in the electrolytic chamber B. The peroxide ions react with Li + to form lithium peroxide; the external fluid pump is used to pump the electrolyte B containing Li + into the electrolytic chamber B, and the original electrolyte B containing Li + in the electrolytic chamber B carries the generated lithium peroxide into the solid recovery and separation module, and lithium peroxide is separated.

[0014] Preferably, the electrolyte of the electrolyte A containing no Li + is tetrabutylammonium perchlorate (TBAClO4), and the solvent is dimethyl sulfoxide (DMSO).

[0015] Preferably, the electrolyte of the electrolyte B containing Li + is lithium perchlorate (LiClO4), and the solvent is dimethyl sulfoxide.

[0016] The solvent of the electrolyte in the present invention is an organic solution with a high donor number (DN). The high DN value is more conducive to promoting the growth of products in the solution mechanism (Energy Environ. Sci., 2024, 17, 8057 - 8077. Adv. Funct. Mater. 2024, 34, 2302397. Chem. Rev. 2020, 120, 14, 6626 - 6683 ) 。

[0017] The beneficial technical effects of the present invention are as follows:

[0018] The lithium peroxide preparation device provided by the present invention decouples the electrolyte to separate the solid product lithium peroxide. The position where lithium peroxide is generated and the electro - chemical reaction site are both on the positive electrode side of the Li - O2 battery, realizing the full utilization of the electrode space, extending the service life of the Li - O2 battery, and achieving continuous batch production of the Li2O2 lithium supplement agent.

[0019] The solid product Li2O2 separated by the present invention has more defect sites compared with that produced commercially, enabling higher ionic conductivity and being used as an efficient lithium supplement agent for lithium - ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of the flow - type Li - O2 battery with decoupled electrolyte in Example 1 of the present invention.

[0021] Figure 2 It is a schematic structural diagram (a) of the flow - type Li - O2 battery used in Example 1 of the present invention and a schematic structural diagram (b) of a traditional Li - O2 battery.

[0022] Figure 3 It is a schematic diagram of the generation of lithium peroxide in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention. It should be understood that the terms used in the present invention are only for describing specific implementation modes and are not used to limit the present invention.

[0024] It should be noted that the parts not described in detail in the present invention are all conventional operation means in the art and are not the focus of the present invention.

[0025] In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0026] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of this invention.

[0027] Regarding the use of "comprising", "including", "having", "containing", etc. in this text, they are all open-ended terms, meaning including but not limited to.

[0028] Example 1

[0029] Preparation of lithium peroxide using a decoupled electrolyte flow Li-O2 battery:

[0030] (1) Multi-walled carbon nanotubes were sprayed on carbon paper as Electrode A (positive electrode). The loading amount of multi-walled carbon nanotubes on Electrode A was 0.5 mg / cm 2 , the thickness of Electrode A was 215 μm, and the diameter was 8 mm; a lithium sheet with a diameter of 16 mm and a thickness of 1 mm was used as the negative electrode.

[0031] (2) Assemble the flow Li-O2 battery with a decoupled electrolyte according to the structure shown in Figure 1 . Among them, the specific structure of the flow Li-O2 battery can be seen in Figure 2 a (the material of the solid electrolyte membrane in the figure is LAGP, and the separator is a glass fiber separator), Figure 2 b in is a schematic structural diagram of a traditional Li-O2 battery.

[0032] (3) Discharge at a current density of 0.05 mA / cm 2 . During the discharge process, fresh electrolyte B (0.5 M LiClO4 / DMSO electrolyte) stored in the electrolyte storage tank was pumped into the cavity of the flow Li-O2 battery by a peristaltic pump (the flow rate was controlled at 0.25 mL / min). The electrolyte B in the cavity of the flow Li-O2 battery then entered the solid product recovery and separation device, and ultrapure lithium peroxide was obtained by precipitation. The separated electrolyte B entered the electrolyte storage tank for circulation; the electrolyte A infiltrating Electrode A was 0.5 M TBAClO4 / DMSO electrolyte.

[0033] The schematic diagram of the formation of lithium peroxide in Example 1 can be seen in Figure 3 . Figure 3 shows that during the discharge process, oxygen generates peroxide ions on Electrode A infiltrated with electrolyte A without Li + . The peroxide ions enter the cavity filled with electrolyte B containing Li + through the solid electrolyte membrane and react with Li + to generate lithium peroxide (purity 95%).

[0034] The embodiments described above are only descriptions of the preferred modes of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A lithium peroxide preparation device, characterized in that, Based on the traditional lithium-oxygen battery, the chamber with electrolyte on the positive electrode side is divided into an electrolytic chamber A, a solid electrolyte membrane, and an electrolytic chamber B; wherein, the electrolytic chamber A is located on the positive electrode material side, and the electrolytic chamber B is located on the separator side; the electrolytic chamber A is used to load the electrolyte A without Li + , and the electrolytic chamber B is used to load the electrolyte B containing Li + . The solid electrolyte membrane is used to isolate the electrolyte A without Li + from the electrolyte B containing Li + ; a fluid outlet and a fluid inlet are arranged on the electrolytic chamber B, and the fluid outlet and the fluid inlet are connected to an external fluid pump to form a fluid flow field; a solid recovery and separation module is arranged between the fluid outlet and the external fluid pump for separating the prepared lithium peroxide.

2. The lithium peroxide preparation device according to claim 1, characterized in that, The positive electrode material is a porous electrode.

3. The lithium peroxide preparation device according to claim 1, characterized in that, An electrolyte storage module is provided between the fluid inlet and the external fluid pump.

4. A method for preparing lithium peroxide based on the lithium peroxide preparation device according to any one of claims 1 to 3, characterized in that, It includes the following steps: During the discharging process, superoxide ions are generated on the positive electrode material, and the superoxide ions pass through the electrolyte A contained in the electrolytic chamber A without Li + and permeate into the electrolyte B containing Li + contained in the electrolytic chamber B through the solid electrolyte membrane. The superoxide ions react with Li + to generate lithium peroxide; the external fluid pump is used to pump the electrolyte B containing Li + into the electrolytic chamber B. The original electrolyte B containing Li + in the electrolytic chamber B carries the generated lithium peroxide into the solid recovery and separation module, and lithium peroxide is separated out.

5. The method for preparing lithium peroxide according to claim 4, wherein The electrolyte of electrolyte A without Li + is tetrabutylammonium perchlorate and the solvent is dimethyl sulfoxide.

6. The method for preparing lithium peroxide according to claim 4, wherein, The electrolyte of electrolyte B containing Li + is lithium perchlorate, and the solvent is dimethyl sulfoxide.

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