lithium battery "replenishing lithium" technology

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lithium battery "replenishing lithium" technology

Příspěvekod Winshinepower » 05 kvě 2022 11:11

Winshinepower is a lithium battery manufacturer. At the same time, it shares energy industry trends, battery design, professional skills and knowledge, etc. Today, we will bring you lithium battery replenishment technology. Let's take a look.

Reasons for Lithium Replenishment of Lithium Batteries
At present, the irreversible capacity loss of graphite anode, which is the most widely used in lithium batteries, is more than 6%. For silicon-based and tin-based alloy anodes with high specific capacity, the irreversible capacity loss is even as high as 10% to 20%.

Technical method of lithium battery replenishment
In the case of adding some high-capacity silicon-based anode materials, lithium batteries lead to low coulombic efficiency and low battery capacity in the first week of the battery. Supplementing active lithium is an effective means to solve this problem. At present, there are many ways to supplement active lithium for lithium batteries, mainly two categories: lithium battery negative electrode supplementation and lithium battery positive electrode supplementation.

Lithium supplementation for the negative electrode of lithium batteries includes physically mixed lithiation of metal lithium, such as adding metal lithium powder to the negative electrode or rolling metal lithium foil on the surface of the pole piece; chemical lithiation of lithium batteries, using lithiating agents such as butyllithium to chemically lithiated the negative electrode Lithium pre-insertion; lithium battery self-discharge lithiation, the negative electrode, and metal lithium are contacted in the electrolyte to complete self-discharge lithiation; lithium battery electrochemical pre-lithiation, metal lithium is introduced into the battery as the third electrode, the negative electrode and metal lithium are the first The three-pole composition completes the pre-lithiation of the charge and discharge of the electrode.

Lithium supplementation for the positive electrode of lithium-ion batteries is the addition of lithium-containing compounds with high irreversible capacity to the positive electrode of lithium-ion batteries. Ternary lithium-containing compounds are represented by Li5FeO4 and organic lithium-containing compounds are represented by Li2DHBN and Li2C2O4. The application of lithium battery replenishment technology not only improves the capacity of lithium-ion batteries but also improves the cycle life of silicon-containing anode batteries.

Lithium battery supplementation classification

(1) Lithium foil type lithium supplement for lithium batteries

In the roll-to-roll negative electrode pole piece pre-lithiation method for batch application, the lithium battery metal Sn foil and the metal lithium foil are rolled to roll-to-roll, and the metal lithium alloys with the surface layer of the Sn foil under the action of mechanical force to form LixSn, The pre-lithiated Sn foil maintains good stability in the air. The surface of the pre-lithiated tin foil is slightly discolored after 48 h exposure in a normal environment, and the pre-lithiated tin foil can still maintain 90% of the initial capacity when exposed to 79% humidity air for 12 h. . The coulombic efficiency of the LFP|Sn battery assembled with pre-lithiated Sn foil reaches 94% in the first week and can be cycled stably for 200 weeks. This lithium battery replenishment method is also applicable to Al foil and conventional silicon-carbon negative electrodes.

(2) Lithium battery lithium powder supplement lithium

The lithium battery drop emulsion technology is a very effective method for synthesizing stable lithium powder. Using the drop emulsion technology, a stable layer is coated on the surface of the lithium powder. The composition of the stable layer is lithium carbonate and lithium fluoride. The layered lithium powder can not only improve the cycle life of the lithium anode but also effectively suppress the formation of lithium dendrites. Stabilized lithium metal powder SLMP (stabilized lithium metal powder) is a commercial product produced by FMC Corporation. It has a core-shell structure and is composed of 97% lithium and 3% lithium carbonate coating. The lithium carbonate protective layer is evenly coated on the surface of the lithium powder, which can prevent the adverse side reactions of the lithium powder so that the SLMP can be used in a dry environment without having to be in an inert atmosphere. SLMP has a specific capacity of up to 3600 mA h/g, and its use in anode lithium supplementation can not only improve the capacity of lithium-ion batteries but also improve its first-week storage efficiency and cycle life.

Lithium Battery

(3) Electrochemical Lithium Supplement for Lithium Batteries

In the existing lithium-ion electrochemical system, the pre-lithiation of the negative electrode plate can be completed by introducing metal lithium and the negative electrode to form a counter electrode, and controlling the depth of electrochemical charge and discharge. The electrochemical pre-lithiation of lithium batteries can be divided into ex-situ and in-situ electrochemical pre-lithiation according to the implementation method. In the conventional ex-situ electrochemical pre-lithiation process, the negative electrode plate that needs to be pre-lithiated is first assembled with a metal lithium half-cell. After a specific charge and discharge cycle, the negative electrode plate reaches the set pre-lithiation level, and then the pre-lithiation is carried out. The negative electrode sheet is assembled with a new positive electrode sheet to form a battery.

In order to simplify the process of disassembling and reassembling the battery in the ex-situ electrochemical lithiation method of lithium batteries, the in-situ electrochemical lithiation method has been gradually developed. The in-situ electrochemical lithiation method of lithium-ion batteries needs to redesign the lithium-ion battery. In the assembly process, metal lithium is pre-added as the third electrode, and the negative electrode and the metal electrode are used as the counter electrode to discharge, so that the in-situ compensation of the negative electrode can be realized. lithium. First, the hard carbon negative electrode and the metal lithium electrode are used as the counter electrode to discharge the hard carbon negative electrode to supplement lithium, and then the NCM positive electrode and the lithium supplemented hard carbon negative electrode form an electrochemical system for charge and discharge work.

(4) Lithium battery supplementary lithium

Lithium battery cathode supplementary materials can be directly added in the homogenization process of the cathode slurry without additional process improvement and the cost is low, so it is more suitable for the current lithium-ion battery manufacturing process, and is known as the most promising lithium supplementation technology. .

From the application point of view, a perfect lithium battery cathode supplementary material needs to meet the following four basic requirements:

① The irreversible delithiation process of the lithium supplementary material for the positive electrode of the lithium battery should be within the working voltage range of the positive electrode, that is, its delithiation potential is lower than the upper voltage limit of the positive electrode material, and the lithium intercalation potential is lower than the lower voltage limit of the positive electrode material;

② Lithium battery supplementary materials should exhibit sufficiently high specific energy and volumetric energy density, usually irreversible capacity greater than 350 mA h/g to meet efficient pre-lithiation

③ The lithium supplementary material for the positive electrode of lithium battery should be compatible with the current general production process and battery system. It does not react with NMP, binder, etc. during the production of the pole piece, and has no adverse side reactions with the electrolyte during the cycle. After the first cycle Its decomposition products do not affect the battery cycle;

④ The positive electrode lithium supplement material of lithium battery has good environmental stability and can remain stable in air or dry environment.

Well, the above is the whole content of today. It explained the reasons for using lithium supplementation technology because of the high loss of irreversible capacity of the negative electrode of lithium batteries. It also introduced the technical methods of lithium supplementation for lithium batteries: positive lithium supplementation and negative electrode lithium supplementation, and detailed Four types of lithium supplementation are introduced, namely, lithium foil supplementation, lithium powder supplementation, positive lithium supplementation, and electrochemical lithium supplementation.

More information is being updated continuously. If you want to get more information, please pay attention to Wechat. See you in the next issue.
For more information, please follow the link below:https://www.winshinepower.com/
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