Ni-Rich Cathode Particle Blending for Battery Cycle Stability
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face particle breakage due to expansion and shrinkage of positive electrode active material particles during charge/discharge cycles, leading to deterioration of cycle characteristics.
Innovation Solution
A positive electrode active material comprising Ni-containing lithium composite oxides with specific average particle sizes, particle breaking loads, and BET specific surface areas is used to combine smaller and larger particles, enhancing packing density and reducing particle breakage, thereby improving battery capacity and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If particle size is reduced to increase packing density, then battery capacity increases, but particle breakage occurs during charge/discharge cycles
Solution Approach 1:
The invention changes the particle size parameters of the positive electrode active material. Specifically, it uses particles with an average particle size of 3 μm or more (preferably 5 μm or more), which reduces particle breakage during charge/discharge cycles while still achieving high packing density and battery capacity through optimized particle size distribution.
Solution Approach 2:
The invention employs a composite particle structure consisting of a core region and a shell region with different properties. The core region has a specific density and crystal structure, while the shell region provides mechanical strength and protection. This composite structure allows the material to maintain high capacity while resisting particle breakage during cycling.
2Quantity of substance
If high Ni content is used to increase battery capacity, then capacity increases, but particle breakage and cycle deterioration worsen
Solution Approach 1:
The invention optimizes the Ni content parameter to be 80 mol % or more (high Ni content) for achieving high capacity, while simultaneously controlling the average particle size to be 3 μm or more and establishing a specific crystal structure with space group R-3m. These parameter changes ensure that the high Ni content material maintains sufficient mechanical strength and resists particle breakage during cycling.
Solution Approach 2:
The invention creates a composite oxide structure with the formula Li1+aNixCoyM1-x-yO2 (where M is a transition metal element). This composite material combines Ni for high capacity with Co and other transition metals that provide structural stability and mechanical strength, thereby preventing particle breakage even at high Ni content levels.
Data Source
AI summary
Each of the Ni-containing lithium-based complex oxide A and the Ni-containing lithium-based complex oxide B contains Ni in an amount of 55 mol % or more relative to the total number of moles of metal elements excluding Li, the Ni-containing lithium-based complex oxide A has an average primary particle diameter of 2 μm or more, an average secondary particle diameter of 2 to 6 μm, a particle fracture load of 5 to 35 mN and a BET specific surface area of 0.5 m2/g to 1.0 m2/g, and the Ni-containing lithium-based complex oxide B has an average primary particle diameter of 1 μm or less, an average secondary particle diameter of 10 to 20 μm, a particle fracture load of 10 to 35 mN and a BET specific surface area of 0.1 m2/g to 1.0 m2/g.