Electrolyte containing additives and a lithium ion battery comprising the same

Electrolyte for lithium metal batteries forming an organic-inorganic protective layer using a CS2-phosphorus sulfide solution

This technology involves adding both carbon disulfide (CS2) and phosphorus sulfide to the electrolyte of secondary batteries that use lithium metal or lithium alloy anodes. These two additives form an organic-inorganic composite protective layer on the lithium metal surface, suppressing dendrite growth and improving cycle life.

Using lithium metal as an anode has historically caused issues with the formation of a thick resistive layer due to reactions with the electrolyte. Furthermore, short circuits caused by dendrites and the accumulation of dead lithium have limited battery efficiency and cycle life.

This technology is configured by mixing a solution of solid phosphorus sulfide dissolved in liquid carbon disulfide into a carbonate-based electrolyte. CS2 aids in the formation and stabilization of the lithium metal protective layer, while effectively delivering phosphorus sulfide—which is otherwise poorly soluble in carbonate solvents—to create an effective organic-inorganic composite film on the lithium metal surface. It can be applied to lithium metal secondary batteries and electrolyte additive packages for lithium alloy anode cells, allowing for the improvement of the anode interface simply by adjusting the additive combination while utilizing existing carbonate electrolyte production lines.

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Key Features:

• A lithium ion battery anode configured to face a cathode, including lithium metal or a lithium alloy
• An electrolyte containing a lithium salt, a carbonate-based solvent, and carbon disulfide and phosphorus sulfide as lithium metal stabilizing additives
• A step of preparing a phosphorus sulfide-carbon disulfide solution by dissolving solid phosphorus sulfide in liquid carbon disulfide
• A carbonate-based solvent in which EMC linear carbonate and FEC cyclic carbonate are mixed in a volume ratio of 1:1 to 4:1

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This invention was developed with support from the Ministry of Trade, Industry and Energy's GET-Future Laboratory program for next-generation lithium-ion batteries.

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