Positive electrode lithium supplementing method of lithium ion battery, product of positive electrode lithium supplementing method and application of product

Abstract

The invention provides a positive electrode lithium supplementing method of a lithium ion battery, a product of the positive electrode lithium supplementing method and an application of the product. The positive electrode lithium supplementing method comprises the steps that a positive electrode active substance, auxiliary materials and a positive electrode lithium supplementing agent are mixed through a dry method, a mixed powder is obtained, then a lithium supplementing positive electrode pole piece is prepared, and the positive electrode lithium supplementing agent comprises Li3N. Accordingto the method, an operation process is simplified, and consumption of a side reaction between Li3N in the positive electrode lithium supplementing agent and a solvent is avoided by dry mixing so thata lithium supplementing effect is improved, the lithium supplementing positive plate with correspondingly improved porosity is obtained, and a first effect, the energy density, the cycle performanceand the rate capability of a battery cell are improved; and after lithium supplementation, byproduct nitrogen of the positive electrode lithium supplementation agent Li3N is removed by negative pressure in a formation stage so that the structure and the performance of the battery are not influenced. The positive electrode lithium supplementing method has the characteristics of low cost, simplicityand convenience in operation and a good lithium supplementing effect.

Description

technical field [0001] The invention belongs to the field of batteries, and relates to a method for replenishing lithium at the positive electrode of a lithium ion battery, a product thereof and a product application. Background technique [0002] Lithium-ion secondary batteries are widely used due to their high output voltage, good cycle performance, high energy density, and environmental friendliness. With the decrease of fossil energy and the rising awareness of global environmental protection, new energy electric vehicles are considered to be the best choice to replace fuel vehicles in the future. The popularity of new energy vehicles inevitably puts forward higher and higher requirements on the performance of lithium-ion batteries, such as long battery life, which gives market demand and resource supply to the research and development of high-energy-density batteries. While ensuring battery safety performance, rate performance, and cycle performance requirements, highe...

AI Technical Summary

Problems solved by technology

But at the same time, it also caused the residue of non-lithium source components in the lithium supplement material, leaving more impurities, causing serious self-discharge of the battery cell, and a decrease in the discharge capacity.

[0006] In terms of negative electrode lithium supplementation, as reported in CN1290209C, lithium metal, negative electrode material and non-aqueous liquid are mixed to form a slurry, the slurry is coated on the negative electrode current collector, and the dry slurry is used to prepare the battery. Although this method can improve the initial efficiency, but Due to the high reactivity of metal lithium, the entire operation needs to be carried out in an anhydrous and dry environment, resulting in difficult operation and high equipment cost.

In addition, the use of non-aqueous solvents further reduces the safety of the experiment; metal lithium is directly coated on the surface of the negative electrode active material or the surface of the current collector for lithium supplementation. Although it can achieve the effect of lithium supplementation, it will cause uneven lithium supplementation. Excessive lithium current causes hidden dangers such as damage to the structure of the active material, such as CN1830110B, CN102082288A and JP1996027910; metal lithium powder is evenly sprayed on the surface of the negative electrode after cold pressing through an electrostatic field, and the lithium powder and the negative electrode sheet are effectively compounded by rolling again. The purpose of lithium supplementation is achieved, but there are also problems such as difficulty in dust control, low production safety, large particle size distribution, and abnormal fluctuations in the range of lithium supplementation, such as CN102779975A and CN102779978A; in addition, as described in CN104584278A and CN110224182A, the It is connected to the metal lithium and the negative electrode of the battery cell, and the lithium supplement to the negative electrode sheet is realized through the charging and discharging process, but there are also problems such as difficult operation and difficult production.

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