Ni-Rich Cathode Composition to Limit Particle Cracking in Li-Ion Batteries
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries using Ni-containing lithium composite oxides face issues with particle cracking and capacity deterioration due to expansion and shrinkage during charge and discharge cycles, particularly under elevated temperatures, which affect storage and cycle characteristics.
Innovation Solution
Combining two types of Ni-containing lithium composite oxides with different average particle sizes, where smaller particles have larger primary sizes and larger particles are coated to enhance bonding strength, inhibiting particle cracking and improving load at fracture, thereby enhancing storage and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Ni-containing lithium composite oxides with high Ni contents are used as positive electrode active materials, then battery capacity increases, but particle cracking occurs due to expansion and shrinkage during charge and discharge, leading to deterioration of storage and cycle characteristics
Solution Approach 1:
The patent applies parameter changes by controlling the average particle size within a specific range (3 μm to 8 μm) and optimizing the Ni content (50 mol% or more) to balance capacity and structural stability. This parameter optimization reduces excessive expansion and shrinkage during charge-discharge cycles, thereby抑制ing particle cracking while maintaining high battery capacity
Solution Approach 2:
The patent uses composite materials by combining Ni-containing lithium composite oxide with other materials having different mechanical properties and expansion characteristics. This composite structure provides mechanical support and buffers the expansion-shrinkage stress, preventing particle cracking and improving storage and cycle characteristics while maintaining high capacity
2Quantity of substance
If small and large particles with different average particle sizes are combined to improve packing density, then battery capacity increases, but particle cracking and capacity deterioration occur under elevated temperature environments
Solution Approach 1:
The patent optimizes the particle size parameter by combining particles with average sizes in the range of 3 μm to 8 μm, which provides an optimal balance between packing density and mechanical strength. This size optimization ensures sufficient contact area for electrochemical reactions while maintaining structural integrity under thermal stress, preventing capacity deterioration at elevated temperatures
Solution Approach 2:
The patent employs composite materials with different particle sizes and compositions, where larger particles provide structural stability and smaller particles fill voids to improve packing density. This composite particle system enhances both capacity and thermal stability, preventing cracking and capacity loss under elevated temperature conditions
Data Source
Figure 1~2A
Figure 2B
AI summary
This positive electrode active material for nonaqueous electrolyte secondary batteries comprises an Ni-containing lithium composite oxide A and an Ni-containing lithium composite oxide B. Each of the Ni-containing lithium composite oxide A and the Ni-containing lithium composite oxide B contains 50% by mole or more of Ni relative to the total number of moles of the metal elements excluding Li; the Ni-containing lithium composite oxide A has an average primary particle diameter of 2 µm or more, an average secondary particle diameter of from 2 µm to 6 µm, and a particle breaking load of 5 mN or more; and the Ni-containing lithium composite oxide B has an average primary particle diameter of 1 µm or less, an average secondary particle diameter of from 10 µm to 20 µm, and a particle breaking load of 20 mN or more, while having a coating layer on the surface of each primary particle.