Boehmite/inert lithium powder composite slurry, lithium supplementing negative plate, preparation method thereof and lithium ion battery

Abstract

The invention discloses boehmite / inert lithium powder composite slurry, a lithium supplementing negative plate, a preparation method of the boehmite / inert lithium powder composite slurry, a preparation method of the lithium supplementing negative plate, and a lithium ion battery. The boehmite / inert lithium powder composite slurry comprises the following components in parts by weight: 5-15 parts ofboehmite, 1-3 parts of inert lithium powder, 3-8 parts of a binder, 0.01-1 part of a conductive agent and 75-90 parts of a solvent. According to the boehmite / inert lithium powder composite slurry, boehmite is adopted as an inorganic filler for inert lithium powder coating, the lithium supplementing effect of the pole piece can be remarkably improved, the process is simple, the cost is low, and the lithium supplementing uniformity is excellent.

Description

technical field [0001] The invention relates to the technical field of energy storage devices, in particular to a boehmite / inert lithium powder composite slurry, a lithium supplement negative electrode sheet, a preparation method thereof and a lithium ion battery. Background technique [0002] Lithium-ion batteries are widely used because of their advantages such as high working voltage, large specific energy, small size, light weight, long cycle life, low self-discharge, no memory effect, and no pollution, and are a research hotspot in the field of energy storage today. In recent years, the rapid development of new energy vehicles, smart grids, and distributed energy storage has put forward higher requirements for the energy density of energy storage devices. In order to further increase the energy density of batteries, high-capacity anode materials (such as silicon-based, tin-based, and metal oxides, etc.) have been introduced into lithium-ion batteries. However, unlike l...

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Problems solved by technology

Among the existing pre-lithiation methods of inert lithium powder, the most simple and direct method is the direct mixing method, that is, adding lithium powder during the slurrying process of the negative electrode material, but through this method, lithium powder will be dissolved inside or on the surface of the pole piece A lot of holes are left, which not only reduces the compaction density, but also may generate lithium dendrites in the thinner area of ​​the pole piece; the second is dry lithium supplementation, and dry lithium powder lithium supplementation on the surface of the negative electrode is also necessary in practical applications. It is more convenient and direct, but due to the large dust in this method, it has great potential safety hazards; at the same time, the fluctuation range of its pre-lithiation is wide and it is difficult to control through the way of dusting.

The third is wet lithium supplementation. Lithium powder is dissolved in an organic solvent and coated on the surface of the negative electrode sheet. Although this wet lithium supplementation effectively solves the dust problem encountered in dry lithium supplementation, the density of lithium powder is relatively high. Small, easy to float, it is difficult to disperse evenly when directly added to the solvent

[0004] At present, lithium supplementation with lithium powder has problems such as difficult dispersion, poor uniformity of lithium supplementation, and difficulty in controlling the amount of lithium supplementation. After lithium supplementation with lithium powder, the surface of the pole piece is likely to be unevenly distributed due to excessive lithium powder, and the interface impedance is large. When the lithium-ion battery is being charged, there is insufficient lithium intercalation space in the negative electrode, Li + The resistance of the embedded negative electrode is too large, and the Li + Abnormalities such as deintercalation from the positive electrode too quickly but unable to intercalate in the negative electrode in the same amount occur. Li+ that cannot be intercalated in the negative electrode can only get electrons on the surface of the negative electrode, thereby forming lithium dendrites, resulting in lithium precipitation.

Lithium analysis not only greatly reduces the effect of lithium powder pre-lithiation, but also reduces the performance of the battery and greatly shortens the cycle life. It also limits the fast charging capacity of the battery and may cause safety problems such as combustion and explosion.

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