Difunctional electrolyte applicable to embedded and conversion type lithium battery, preparation method, and lithium battery comprising electrolyte

Abstract

The invention relates to a difunctional electrolyte applicable to an embedded and conversion type lithium battery, a preparation method, and a lithium battery comprising the electrolyte. The electrolyte is formed by dispersing a multi-component ether type ionic liquid into a fluoro-ether type solvent; the positive ions of the multi-component ether type ionic liquid are a lithium ion chelate; freeof free-state ether or carbonic ester, a secondary reaction with graphite or polysulfide ions can be prevented effectively, so that the electrolyte can be applicable to an embedded type electrode material and a conversion type electrode material; by introducing fluoro-ether, the electrolyte viscosity is lowered, and meanwhile, electrochemical stability and thermal stability of the electrolyte arenot influenced; the initial charging efficiency can reach 80% or above, and after 100 cycles, the specific capacity has little loss; in addition, the electrolyte has high flame retardant effect, and high temperature performance and safety of the electrolyte are improved, so that joint use of the conversion type electrode material and the embedded type electrode material can be realized; and consequently, the battery energy density is improved, and battery cost is lowered.

Description

technical field [0001] The invention relates to the technical field of lithium ion battery electrolyte, in particular to a bifunctional electrolyte suitable for intercalation and conversion lithium batteries, a preparation method and a lithium battery containing the same. Background technique [0002] In recent years, with the rapid increase in the production of new energy vehicles, the demand for lithium power batteries for vehicles has continued to explode. Judging from the shipment trend in the past five years, my country's power battery shipments have been below 1GWh before 2014. It exceeded 3GWh for the first time in 2016, and the market began to enter a period of rapid growth. In 2016, it reached 29.8GWh, nearly double that of 2015. This is closely related to the development trend of my country's new energy vehicle market. [0003] Range, safety and price are the decisive factors for the rapid promotion of new energy vehicles. Batteries currently account for 1 / 3 to 1 / 2...

AI Technical Summary

Problems solved by technology

Nevertheless, lithium-sulfur batteries are still far away from practical applications. The main reasons include: poor safety, low flash point, volatile, and poor safety of ether electrolytes, which make batteries unable to adapt to high temperature (such as 50°C) working environments ; The compaction density of sulfur electrodes is low, and the overall energy density of the battery is limited

Mixing lithium-ion battery cathode materials with sulfur is an effective measure to increase the compaction density of the electrode and thereby increase the energy density of the battery. + Co-embedding graphite, causing problems such as graphite peeling and pulverization, and its oxidation resistance is also poor, so it cannot be applied to lithium-ion batteries; the carbonate electrolyte commonly used in lithium-ion batteries cannot be applied to lithium-sulfur battery systems: The polysulfide ions generated during charging and discharging are easy to react with carbonates and undergo irreversible transformation

Therefore, the electrolyte has become a bottleneck for intercalation electrode materials combined with sulfur

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