Micro-textured negative plate for preliminary lithium supplementing and preparation method thereof

Abstract

The invention discloses a micro-textured negative plate for preliminary lithium supplementing and a preparation method thereof. The micro-textured negative plate for preliminary lithium supplementingcomprises a negative current collector, micro-textures, preliminary lithium supplementing layers covering the surfaces of pits of the corresponding micro-textures, and active material dressing layerscovering the negative current collector and filling the pits, wherein the micro-textures are arranged on single or double side surfaces of the negative current collector and are of a concave-convex structure. The preliminary lithium supplementing layers are arranged between the negative current collector and the active material dressing layers and are only located on the surfaces of the pits of the micro-textures, so that the cohesive force between active materials and the current collector is not affected, the expansion stress of the active materials can be dispersed, the irreversible capacity is effectively compensated and the first efficiency is improved. Therefore, according to the micro-textured negative plate for preliminary lithium supplementing disclosed by the invention, effectivelithium supplementing can be achieved, volume expansion of the negative plate is relieved, the stability of a negative electrode system is ensured and the problem in the field at the present stage issolved.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, and more specifically relates to a micro-textured negative electrode sheet for pre-complementing lithium and a preparation method thereof. Background technique [0002] Lithium-ion batteries are widely used in various fields due to their high energy density, long service life, no memory effect, and high safety. With the deepening of research on lithium battery materials, the specific capacity of traditional carbon-based lithium intercalation materials is approaching the limit. In order to meet the demand for higher energy density, the research and development of negative electrode materials tends to be high-capacity materials and composite materials that can be alloyed with lithium. Such as silicon base, tin base, etc. [0003] However, the high-capacity negative electrode material used for the negative electrode of lithium-ion secondary batteries has an irreversible capacity of up to ...

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Problems solved by technology

[0003] However, the high-capacity negative electrode material used for the negative electrode of lithium-ion secondary batteries has an irreversible capacity of up to 40%-70% for the first time, and it needs to consume a large amount of electrolyte and lithium ions released from the positive electrode material, resulting in battery stability, charging and discharging. Efficiency and discharge specific capacity are reduced; and in the process of charging and discharging, high-capacity negative electrode materials are often accompanied by huge volume expansion, or even rupture and fall off, resulting in failure of electrical contact between active materials, active materials and current collectors, resulting in The energy density and cycle life of the battery decrease

[0004] As far as the existing technology is concerned, the following methods are generally used to compensate the first irreversible capacity of the high-capacity negative electrode: one is to directly apply lithium powder, lithium foil, lithium-containing solution or slurry on the surface of the negative electrode sheet for lithium supplementation, However, the lithium-replenishing layer of this method is located on the surface of the negative electrode sheet, which cannot alleviate the volume expansion of the negative electrode, and excessive lithium accumulation on the surface of the negative electrode sheet is easy to form lithium dendrites, causing potential safety hazards; another method is to first apply the lithium-replenishing layer On the surface of the current collector, the active material is then coated to prepare the negative electrode sheet. After the lithium supplementation layer is completed, pores will be formed between the current collector and the active material, which reserves a space for the expansion of the active material. However, when fully covered After the continuous lithium supplement layer disappears, it will cause the failure of the bond between the current collector and the active material, and ultimately affect the stability of the negative electrode system.

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