Method for inhibiting metal lithium dendritic crystal growth

Abstract

The invention provides a method for inhibiting the metal lithium dendritic crystal growth, which is achieved by using electrolyte containing a main lithium salt and an auxiliary lithium salt, whereinthe auxiliary lithium salt is selected from at least one of lithium difluorophosphate and lithium bis(fluorosulfonyl)imide. The method provided by the invention can inhibit the metal lithium dendriticcrystal growth; the stability of a metal lithium negative electrode SEI film is improved, so that the safety of a metal lithium battery is improved.

Description

technical field [0001] The invention relates to a method for inhibiting the growth of lithium dendrites, in particular to a method for inhibiting the growth of lithium dendrites in lithium ion batteries. Background technique [0002] Lithium-ion batteries are widely used in various fields, such as various portable electronic devices, due to their advantages such as high working voltage, high energy density, low self-discharge rate, no memory effect, long cycle life and no pollution. In the national strategic plan, electric vehicles and high-energy-density vehicle batteries occupy an important position, and are key industries supported and developed by the state. At the same time, with the rapid development of clean energy such as wind energy, solar energy and biomass energy, the development of energy storage batteries used to convert these clean energy into the grid has also been accelerated, and lithium batteries are also an important product of energy storage batteries. H...

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Problems solved by technology

[0004] (1) Lithium metal has a relatively low Fermi energy level, and a stable SEI film cannot be formed between it and the electrolyte, so the SEI film is repeatedly formed during the cycle to cause internal friction between lithium metal and the electrolyte;

[0005] (2) The volume change during the deposition / dissolution process of metal lithium is very large, which intensifies the rupture rate of the SEI film on the surface of metal lithium;

[0006] (3) The deposition / dissolution of metal lithium during the cycle is uneven, and it is easy to form metal lithium dendrites, which in turn puncture the separator and affect the safety of the battery

[0009] (2) Sci.Adv.2017; 3:e1601659 reported a method to prevent the growth of metal lithium dendrites by using all-solid electrolytes. This method has the problem of high interface impedance between the solid electrolyte and metal lithium;

[0010] (3) Nature Energy, 2017, 6: nenergy2017119. It is disclosed that a protective layer such as lithium chloride is formed on the surface of metal lithium by in-situ or ex-situ methods to prevent the generation of metal lithium dendrites during cycling. The lithium ion conductivity of the protective layer obtained by the method is low, which reduces the rate performance of the battery;

[0011] (4) J.Am.Chem.Soc.2013,135,4450-4456 discloses that by adding additives such as CsNO to the electrolyte 3 and FEC, etc., to promote the formation of a stable SEI film to inhibit the growth of lithium metal dendrites, however, these additives can only be used for low-rate deposition

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