Slanted Columnar Electrode Particles for Lithium Battery Stress Relief
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Solution Overview
Problem
Lithium secondary battery electrodes with columnar particles experience stress and cracking due to expansion during charge and discharge cycles, leading to reduced cycle characteristics and efficiency, as existing methods fail to effectively disperse stress and maintain the connection between active material layers and current collectors.
Innovation Solution
The electrode design incorporates columnar particles with bends, allowing for controlled growth angles and porosity, which disperses stress at bends and reduces the exposed current collector area, enhancing lithium desorption efficiency and cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If columnar particles are formed upright normal to the current collector surface, then expansion stress is relieved, but charge and discharge efficiency decreases due to lithium precipitation on exposed current collector
Solution Approach 1:
The columnar particles are designed with asymmetric orientation, slanted at a specific angle (e.g., 45 degrees) relative to the normal direction of the current collector surface. This asymmetric configuration allows the particles to relieve expansion stress while minimizing the exposed current collector area, thereby improving charge and discharge efficiency compared to upright columnar structures.
Solution Approach 2:
The invention introduces a new dimensional parameter - the slant angle of columnar particles relative to the normal direction. By controlling this angular dimension, the patent optimizes both stress relief capability and electrochemical efficiency, transforming the traditional upright (0-degree) configuration into a slanted configuration that balances mechanical and electrical performance.
2Quantity of substance
If active material layer thickness is increased to increase energy density, then stress at contacting portions increases, but this intensifies cracking risk
Solution Approach 1:
The invention applies local quality by creating a non-uniform stress distribution through slanted columnar particles. The slant angle causes stress to be distributed along the inclined interfaces between particles and current collector, rather than concentrating at the bottom contacting portions. This localized stress redistribution allows thicker active material layers to be used without proportionally increasing crack risk.
Solution Approach 2:
The slanted columnar particle configuration acts as a preliminary stress management mechanism. By pre-designing the inclined geometry before battery operation, the structure anticipates and distributes expansion stresses along favorable pathways, preventing stress concentration that would lead to cracking in thicker electrodes during charge-discharge cycles.
3Strength
If columnar particles are slanted to relieve expansion stress, then stress dispersal improves, but manufacturing complexity increases
Solution Approach 1:
The invention controls the slant angle of columnar particles within a specific range (e.g., 30-60 degrees relative to normal direction) to optimize stress dispersal while maintaining manufacturing feasibility. By defining a parameter range rather than requiring precise unique angles, the patent balances performance improvement with manufacturing simplicity, allowing standard deposition techniques to produce the desired slanted structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively disperses stress at bends, preventing cracking and improving charge and discharge efficiency, while allowing for a sufficient gap between particles to relieve expansion stress, thus enhancing the cycle characteristics of lithium secondary batteries.
Implementation Method 1
the columnar particles are capable of absorbing and desorbing lithium
Data Source
AI summary
An electrode for a lithium secondary battery including a sheet-like current collector and an active material layer carried on the current collector. The active material layer is capable of absorbing and desorbing lithium, and the active material layer includes a plurality of columnar particles having at least one bend. An angle θ1 formed by a growth direction of the columnar particles from a bottom to a first bend of the columnar particles, and a direction normal to the current collector is preferably 10° or more and less than 90°. When θn+1 is an angle formed by a growth direction of the columnar particles from an n-th bend counted from a bottom of the columnar particles to an (n+1)-th bend, and the direction normal to the current collector, and n is an integer of 1 or more, θn+1 is preferably 0° or more and less than 90°.