NCA Cathode Powder Surface Treatment for Low Gas Generation
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Solution Overview
Problem
Existing lithium nickel-based positive electrode active materials for lithium ion batteries suffer from significant gas generation during charging and discharging, leading to safety issues such as deformation and rupture, particularly in laminate cells, and existing treatments to reduce gas generation compromise the capacity and cycle characteristics of the electrodes.
Innovation Solution
A lithium metal composite oxide powder with a composition of LiaNibCocAldO2, treated with an aqueous solution of an organic metal salt or sodium thiosulfate, is used as a positive electrode active material, which is then processed into electrodes and batteries to minimize gas generation while maintaining high discharge capacity and cycle retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If NCA based positive electrode active material is used to achieve high discharge capacity exceeding 190 mAh/g, then the discharge capacity is improved, but gas generation increases significantly during charging and discharging
Solution Approach 1:
An aqueous solution containing a specific organic compound is introduced as an intermediary treatment between the synthesis of NCA material and its use in battery assembly. This treatment layer modifies the material surface to suppress gas generation while preserving the bulk high-capacity properties of the NCA structure.
Solution Approach 2:
The invention changes the surface chemical parameters of the NCA material through aqueous treatment, modifying surface composition and structure without altering the bulk stoichiometry. This allows the material to maintain high discharge capacity while reducing gas evolution during cycling.
2Object-generated harmful factors
If washing treatment is applied to suppress gas generation, then gas generation is reduced, but the capacity of the positive electrode active material is reduced
Solution Approach 1:
Instead of conventional washing that removes surface material, the invention applies a controlled aqueous treatment that modifies surface parameters (composition, structure, or coating) to suppress gas generation while preserving or even enhancing the active material's capacity.
Solution Approach 2:
The treatment creates a localized modification at the material surface that specifically addresses gas generation without affecting the bulk material properties. The surface layer acquires different characteristics than the interior, allowing gas suppression while maintaining high capacity.
3Object-generated harmful factors
If neutralization treatment using acid solution is applied to reduce gas generation, then gas generation is suppressed, but cycle characteristics deteriorate
Solution Approach 1:
An aqueous solution with specific organic compounds serves as an intermediary treatment that suppresses gas generation without the harsh effects of acid neutralization. This gentler treatment preserves the material's structural integrity and electrochemical stability over repeated cycling.
Solution Approach 2:
The invention uses a simple aqueous solution treatment instead of complex acid neutralization processes, achieving gas suppression through a milder, more controllable method that doesn't compromise long-term battery reliability.
Data Source
AI summary
A lithium metal composite oxide powder for use in a positive electrode active material for a lithium ion battery has a composition of LiaNibCocAldO2 (wherein, a=0.8 to 1.2, b=0.7 to 0.95, c=0.02 to 0.2, d=0.005 to 0.1, and b+c+d=1). The powder has been treated with an aqueous solution of an organic metal salt and soluble aluminum salt and does not cause volume expansion due to gas generation. A positive electrode active material with the lithium metal composite oxide powder has a large discharge capacity, excellent cycle characteristics, and suppressed gas generation.