Cathode for lithium secondary battery and lithium secondary battery comprising the same

Cathode compensating for irreversible capacity without pre-lithiation using a hexagonal lithium silicon oxide additive

This technology utilizes a lithium-containing silicon-based oxide (Li8-xSi1-yMyO6-z) as a cathode additive. It effectively compensates for the initial irreversible capacity of the anode by releasing lithium ions through an oxygen ion oxidation mechanism during the initial charge.

Silicon-based anode active materials suffer from high initial irreversible capacity, which reduces the overall energy density of the cell. Existing pre-lithiation processes intended to solve this issue are limited by high fire risks, increased costs, and process complexity.

This technology introduces a lithium silicon-based oxide with a hexagonal crystal structure (space group P63cm) as a cathode additive. It smoothly supplies lithium to the anode during the first charge to offset initial irreversible capacity, while maintaining stable, high-capacity characteristics in subsequent cycles due to low reactivity. Applicable to high-energy electric vehicle cells and small IT device batteries that use silicon anodes, it allows for the compensation of initial efficiency losses using only existing cathode coating lines, eliminating the need for hazardous pre-lithiation equipment.

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Key Features:

• A lithium secondary battery comprising a cathode, an anode, and a separator and electrolyte positioned between the cathode and the anode
• A cathode additive with the chemical formula Li8-xSi1-yMyO6-z that compensates for anode irreversible capacity alongside the cathode active material
• A cathode additive with a hexagonal crystal structure (space group P63cm), included in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the cathode active material
• An anode for a lithium secondary battery that remains in a non-pre-lithiated state and contains a silicon (Si)-based material as an anode active material

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