Lithium ion battery electrolyte and preparation method thereof

Abstract

The invention provides a lithium ion battery electrolyte and a preparation method thereof, belonging to the technical field of lithium ion batteries. According to the lithium ion battery electrolyte provided by the invention, in commercial electrolyte, a lithium modified inorganic layered material and a high molecular polymer with ionic conductivity are directly introduced, a lithiophilic organiclayered material and the high molecular polymer directly participate in reconstruction of lithium metal cathode surface solid electrolyte membrane (SEI) to strengthen a lithium cathode and realize a function of inhibiting metal dendritic crystal growth. Moreover, the lithiophilic material provided by the invention cannot be consumed as time goes on and can stabilize the lithium metal cathode for long time. The lithium modified inorganic layered material provided by the invention has very strong mechanical performance and relatively higher thermal stability and fire resistance, and greatly improves safety performance of the battery; moreover, the inorganic layered material and the high molecular polymer material needed for the lithium ion battery electrolyte are industrial materials which are very low-cost and compatible to industrial production of the existing lithium battery electrolyte.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a lithium ion battery electrolyte for suppressing lithium dendrites and a preparation method thereof. Background technique [0002] With the continuous increase of human demand for energy and the excessive grabbing of fossil energy, oil resources are becoming increasingly depleted and environmental problems are becoming increasingly severe, seriously affecting the development of the world economy and the survival of human beings, making people's demand for new energy more urgent. Therefore, the development of renewable and clean new energy is of great significance to saving resources, reducing environmental pollution and protecting human health. [0003] Traditional lithium-ion batteries (LIBs) use graphite as the negative electrode, the positive electrode uses oxide materials that can intercalate / extract lithium ions, and the electrolyte is an organic s...

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Problems solved by technology

In terms of lithium metal, a common method, such as a method reported in Chinese patent CN103384000A, is to inject lithium metal into a 3D skeleton structure through high-temperature melting to improve the stability of lithium negative electrodes. Although this method has a certain inhibitory effect on the growth of lithium dendrites, the This method will increase the weight of the battery to a large extent, reduce the energy density of the negative electrode, and the preparation process is cumbersome, which is not conducive to commercial production

Separator coating modification can redistribute the diffusion path of lithium ions to a certain extent and achieve the purpose of inhibiting the growth of lithium dendrites (Adv.Energy Mater., DOI: 10.1002 / aenm.201802430), but due to the The source has not been effectively modified, and the modified layer of the separator is easy to redistribute in the electrochemical cycle, resulting in the insufficient density of the modified layer of the separator, exposing the unmodified layer, and the risk of dendrite growth will reappear (Nat.Commun.,2014, 5,5193)

The modification of the electrolyte is considered to be the most potential method to inhibit the growth of lithium dendrites (Adv.Mater., 2017, 1700007). For example, Chinese patent CN 107275671 A reports a method by adding fluoride nanoparticles to the electrolyte, The purpose of inhibiting the growth of lithium dendrites is achieved through the film-forming characteristics of fluoride nanoparticles on the surface of the negative electrode, but this type of additive will gradually become invalid as the cycle increases, and the protective film formed by this type of additive The conductivity of lithium ions is low, which is not conducive to high-current charge and discharge (such as greater than 3mA / cm 2 )

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