NCM Composite Electrode Density for Crack-Resistant Batteries
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Solution Overview
Problem
Conventional lithium nickel cobalt manganese oxide-based secondary batteries suffer from short lifetime due to particle cracking and oxidation reactions, especially under high-temperature conditions and high potential storage, leading to reduced cycle performance and safety concerns.
Innovation Solution
An electrode with a specific active material-containing layer comprising lithium nickel cobalt manganese composite oxide particles, an electro-conductive agent, and a binder, where the strength ratio of composite material particles to active material particles is between 0.01 and 0.1, and the electrode density is between 3.2 and 3.8 g/cm3, optimizing the balance between strength and permeability to prevent particle cracking and enhance electrolyte penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium nickel cobalt manganese oxide is used as active material to achieve large capacity performance, then battery capacity is improved, but particle cracking and conversion into deteriorated structure occur with cycles leading to short lifetime
Solution Approach 1:
The patent uses composite particles formed by agglomeration of primary particles of lithium nickel cobalt manganese oxide. The composite structure combines multiple primary particles into a secondary particle architecture that maintains high capacity while reducing internal stress during cycling, thereby preventing particle cracking and structure deterioration.
Solution Approach 2:
The patent specifies controlling the compression breaking strength of primary particles within a specific range (0.5-5.0 N) and setting the strength ratio A/B between composite and active material particles within 0.01-0.1. These parameter optimizations balance mechanical strength and flexibility to accommodate volume changes during charge-discharge cycles, improving both capacity and lifetime.
2Quantity of substance
If high density electrode is used to improve battery energy density, then capacity per volume is improved, but particle cracking occurs due to pressing and expansion contraction during charge discharge
Solution Approach 1:
The composite particle structure with controlled strength ratio provides a hierarchical architecture that can accommodate mechanical stress. The agglomeration of primary particles into secondary composites creates internal buffering zones that reduce stress concentration during pressing and volume expansion/contraction, maintaining particle integrity while achieving high electrode density.
Solution Approach 2:
By optimizing the compression breaking strength of primary particles (0.5-5.0 N) and the strength ratio A/B (0.01-0.1), the patent creates particles with appropriate mechanical properties that can withstand pressing forces during electrode manufacturing and volume changes during cycling, preventing cracking while maintaining high density.
3Power
If electrode density is increased to improve output performance, then current output is improved, but electrolyte penetration becomes insufficient
Solution Approach 1:
The patent optimizes electrode density within a specific range (3.2-3.8 g/cm³) that balances two competing requirements: high enough density to ensure good electron conductivity and current output, but not so high as to completely block electrolyte penetration. This parameter optimization maintains both power performance and ionic transport.
Data Source
AI summary
According to one embodiment, provided is an electrode including an active material-containing layer. The active material-containing layer contains composite material particles that include active material particles containing a lithium nickel cobalt manganese composite oxide, an electro-conductive agent, and a binder. A strength ratio A/B of a breaking strength A of the composite material particles to a breaking strength B of the active material particles is within a range of 0.01 to 0.1. A density of the active material-containing layer is within a range of 3.2 g/cm3 to 3.8 g/cm3.