Lithium-supplementing negative electrode piece, preparation method thereof, and lithium ion battery

Abstract

The invention discloses a lithium-supplementing negative electrode piece, a preparation method thereof, and a lithium ion battery. The lithium-supplementing negative electrode piece comprises a negative electrode piece body and a lithium-supplementing composite layer coated on the surface of the negative electrode piece body. The lithium-supplementing composite layer comprises the following raw materials in percentage by mass: 20%-65% of alloy lithium powder; 30%-70% of ceramic powder; and 5%-50% of a binder. According to the lithium-supplementing negative electrode piece disclosed by the invention, by arranging the lithium-supplementing composite layer, the safety performance of the lithium ion battery is enhanced, and the self-discharge performance of the battery is increased from -0.06mv / h to -0.04mv / h. The lithium alloy powder in the lithium-supplementing composite layer can effectively reduce the activity of lithium and reduce the transportation risk; and the ceramic powder can improve the electrolyte absorption performance of the electrolyte and prolong the cycle life of the battery cell.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a lithium-supplementing negative electrode sheet. Background technique [0002] Lithium-ion batteries consume part of the lithium due to the formation of the SEI film during the first charging process, which will cause the loss of lithium in the positive electrode material, thereby reducing the capacity of the battery and resulting in a decrease in the first efficiency. In addition, during the cycle process of lithium-ion batteries, the SEI film is consumed and repaired, and there will be irreversible lithium inside the positive and negative electrodes to varying degrees, resulting in capacity loss, resulting in a decrease in the cycle life of the battery. Usually, lithium supplementation can be used to improve the above problems. [0003] CN201610551220.2 discloses a lithium-supplementing composite diaphragm, which uses a mesh current collector. At present, copper ...

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Problems solved by technology

[0002] Lithium-ion batteries consume part of the lithium due to the formation of the SEI film during the first charging process, which will cause the loss of lithium in the positive electrode material, thereby reducing the capacity of the battery and resulting in a decrease in the first efficiency

In addition, during the cycle process of lithium-ion batteries, the SEI film is consumed and repaired, and there will be irreversible lithium in the positive and negative electrodes to varying degrees, resulting in a loss of capacity, resulting in a decrease in the cycle life of the battery. Usually, the above problems can be improved by supplementing lithium.

[0003] CN201610551220.2 discloses a lithium-supplementing composite diaphragm, which uses a mesh current collector. At present, the production of lithium-ion batteries actually uses copper and aluminum foil, which cannot be applied

Among them, for the design of lithium-ion batteries, for safety reasons, the separator is designed to be larger than the negative electrode in length and width, and the negative electrode is larger than the positive electrode in the direction of length and width. If it exceeds, there will be a risk of combustion and explosion. The part of the separator that exceeds the negative electrode It cannot be filled into the negative electrode, but exists on the diaphragm, which will pose a safety hazard

Coating lithium powder on the diaphragm can be achieved in qualified factories, but for most factories, they need to go to the diaphragm factory to purchase, so the diaphragm with metal lithium powder has potential safety hazards during transportation, and the packaging cost is also high.

[0004] In addition, the technical solution of the patent CN201610551220.2 has high technical barriers, requires the use of fully automated equipment and a new design process, and the need to eliminate existing equipment, so the investment is high and can only be invested in qualified enterprises

[0005] CN201410309553.5 discloses a lithium-ion secondary battery and its lithium-rich negative electrode sheet. Lithium metal is used as the lithium supplement material, but the lithium metal is too active to be suitable for actual operation. Applying a coating containing conductive agents will increase the self-discharge of the battery, and too thin metal oxides will not help safety performance

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