Surface modification method of lithium secondary battery negative electrode, ag modified lithium electrode prepared by using the method and application

Abstract

The invention discloses a lithium secondary battery cathode surface modification method, which comprises the following steps of adopting nano Ag powder as an electrolyte and tetrahydrofuran as a solvent, preparing a nano Ag tetrahydrofuran solution with the concentration being 0.8 to 1.0mg / ml in an argon glove box with H2O being less than 0.1ppm and O2 being less than 0.1ppm, heating and carryingout ultrasonic treatment for 12 to 24h, and obtaining an upper-layer turbid liquid for standby use; adopting a pretreated lithium electrode piece, dripping the turbid liquid on the surface of the lithium electrode piece, standing, after volatilizing tetrahydrofuran, placing under the pressure being 75 to 100Mpa for 20 to 30min, and obtaining the surface alloying-modified lithium electrode. Compared with the prior art, according to the surface modification method provided by the invention, a layer of robust Li-Ag alloy can be generated on a cathode surface during a charge-discharge process, non-faradaic reaction between a lithium cathode and an electrolyte is reduced, lithium dendrites are inhibited, and a cycle performance and a safety performance of a battery are improved.

Description

technical field [0001] The invention belongs to the technical field of electrochemical batteries, and in particular relates to a method for modifying the surface of a negative electrode of a lithium secondary battery, an Ag-modified lithium electrode prepared by the method and an application thereof. Background technique [0002] Under the double pressure of excessive consumption of fossil fuels and environmental pollution, especially for the problem of vehicle exhaust emissions, governments of various countries have promoted the process of low-carbon vehicles and supported the new energy vehicle industry by formulating a series of policies such as strategic planning, technology research and development, and market supervision. The development of new energy vehicles will surely replace traditional fuel vehicles. However, the existing commercial lithium-ion batteries are affected by the negative electrode materials, and it is difficult to meet the mileage requirements of new ...

AI Technical Summary

Problems solved by technology

The use of lithium alloy as the negative electrode reduces the reactivity of the negative electrode, reduces the non-Faradaic reaction between the electrolyte and the negative electrode, promotes the uniform deposition of lithium, and inhibits the formation of dendrites, but at the same time, the overall specific capacity and energy density of the negative electrode are greatly reduced. , the gain outweighs the gain; the use of nano-lithium powder instead of lithium foil improves the performance and increases the manufacturing cost, and the nano-lithium powder is flammable and explosive, and the operation is difficult; pretreatment modification is the most popular research direction at present, but no matter what kind of pretreatment The method and timeliness are difficult to meet the needs of practical applications; the development of new electrolyte systems, including the development of electrolyte additives, electrolyte solvents, new solutes, etc., suitable electrolytes can indeed improve interfacial compatibility and improve battery performance, but the current development is relatively slow

In summary, although various modification methods have made some progress, they still cannot completely eliminate the safety hazards of lithium anodes.

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