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Composite negative electrode, solid-state lithium battery and preparation method of solid-state lithium battery

A solid-state lithium and solid-state electrolyte technology, applied in battery electrodes, secondary batteries, non-aqueous electrolyte battery electrodes, etc., can solve the problem of not being able to permanently prevent short circuits in lithium dendrite batteries, short circuits in batteries, and loss of effectiveness, and achieve rapid The effect of electrochemical reaction, reducing anode impedance, and improving overall performance

Active Publication Date: 2021-02-26
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, the growth of lithium dendrites also exists in solid-state lithium batteries. During the battery cycle, due to high-rate charging or uneven deposition of lithium ions on the surface of the negative electrode of the battery, dendritic lithium metal, namely lithium dendrites, will appear on the negative electrode. , during the lithium ion deposition process, it will gradually grow along the gaps or particle boundaries of the solid electrolyte particles, which will pierce the solid electrolyte layer to connect the positive and negative electrodes, causing the battery to have the risk of internal short circuit
To solve this problem, current collectors with three-dimensional structures are often used as negative electrode current collectors in the prior art, or negative electrode active materials are directly prepared into three-dimensional structures, such as porous structures. This three-dimensional structure can make lithium metal deposition more uniform and reduce lithium branches. However, in the case of high current density or high overpotential, the problem of lithium dendrite growth is still serious; in addition, the method of setting a protective layer or buffer layer between the negative electrode and the solid electrolyte layer can be used to alleviate the problem. The growth of lithium dendrites, however, with the emergence of lithium dendrites and reaction by-products, these protective layers or buffer layers will gradually lose their effectiveness, resulting in the inability to permanently prevent the internal short circuit problem caused by lithium dendrites

Method used

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Examples

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Effect test

preparation example Construction

[0050] In a third aspect, the present invention provides a method for preparing the above-mentioned solid-state lithium battery, comprising the following steps:

[0051] (1) Coating the positive electrode slurry containing the positive electrode active material on the positive electrode current collector to obtain the positive electrode;

[0052] (2) Coating a solid electrolyte on the surface of the positive electrode active material in step (1) to obtain a positive electrode with a solid electrolyte;

[0053] (3) At a temperature lower than the melting point of the liquid alloy, the active layer containing the liquid alloy is combined with the negative electrode current collector to obtain a negative electrode, and then combined with the positive electrode with a solid electrolyte obtained in step (2) to obtain a solid lithium battery;

[0054] Among them, the main component of the liquid alloy is Ga x In y sn z m w , wherein, M is selected from one or more of Bi, Pb, Cd,...

Embodiment 1

[0063] (1) Preparation of positive electrode sheet C

[0064] First prepare the surface with LiNbO 3 Coated cathode material, 1000gLiCoO 2 , 51mL of niobium ethoxide, 12g of lithium ethoxide, 1000mL of deionized water and 1000mL of ethanol were thoroughly mixed, and then added dropwise ammonia water until the pH reached 10 while stirring continuously, and the solution was evaporated to dryness, and the obtained powder was heated at 400°C for 8h. Get LiNbO 3 Coated LiCoO 2 .

[0065] Subsequently, 930 g of coated LiCoO 2 Cathode material, 150 g Li 10 GeP 2 S 12 The solid electrolyte material, 30 g binder butadiene rubber, 20 g acetylene black, and 20 g conductive agent carbon fiber were added to 1500 g solvent toluene, and then stirred in a vacuum mixer to form a stable and uniform positive electrode slurry. The positive electrode slurry was evenly and intermittently coated on both sides of aluminum foil (aluminum foil size: width 160 mm, thickness 16 μm), then dried at...

Embodiment 2

[0074] The same steps as in Example 1 were used to prepare the solid-state lithium battery of this example, the difference being that:

[0075] In step (3), at room temperature and under a protective atmosphere, 1000 g of the negative electrode active material artificial graphite and 200 g of Ga 0.73 In 0.18 sn 0.09 The alloy (liquid state) is mixed, and then stirred in a vacuum mixer to form a stable and uniform negative electrode slurry. The slurry was evenly coated on the copper foil current collector, then cooled to 0 degrees Celsius, and after being pressed by a roller press, it was cut into a negative electrode sheet A with a size of 480 mm (length) × 45 mm (width).

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Abstract

The present invention provides a composite negative electrode, and the negative electrode comprises a negative electrode current collector and an active layer; the active layer comprises a liquid alloy, and the main component of the liquid alloy is GaxInySnzMw, wherein M is selected from one or more of Bi, Pb, Cd, Zn and T1, x + y + z + w = 1, 0.5<x<0.999, 0<=y<0.5, 0<=z<0.3, 0<=w<0.2. When the composite negative electrode is applied to a lithium battery, the problem that lithium dendrites in the lithium battery grow and pierce a solid electrolyte layer can be well solved, and the battery canbe protected for a long time to avoid the problem of internal short circuit caused by the lithium dendrites.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a composite negative electrode, a solid lithium battery and a preparation method thereof. Background technique [0002] Lithium batteries are widely used due to their high energy density and good cycle performance. However, the use of liquid organic solvents as electrolytes can cause battery leakage, gassing, and fire, which pose serious safety hazards to the battery system. . Solid-state lithium batteries can greatly improve the safety performance of batteries because they use solid-state electrolytes to replace the organic liquid electrolytes used in existing batteries. [0003] However, the growth of lithium dendrites also exists in solid-state lithium batteries. During the battery cycle, due to high-rate charging or uneven deposition of lithium ions on the surface of the negative electrode of the battery, dendritic lithium metal, namely lithium dendrites, will appe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/13H01M4/139H01M10/0525
CPCH01M4/13H01M4/139H01M10/0525Y02E60/10
Inventor 历彪郭姿珠胡屹伟
Owner BYD CO LTD
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