Sn-Based Coated Carbon Anode for Lithium Battery Stress Management
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Solution Overview
Problem
Lithium secondary batteries using metal-based anode active materials face issues with volume expansion during charging/discharging, leading to stress and reduced cycle life, making them unsuitable for commercial use.
Innovation Solution
A carbon-based anode active material with a Sn-based coating layer having domains of 1 μm or less in diameter is used, formed through electroplating, to alleviate stress from volume expansion by distributing Sn-based domains uniformly on the carbon material surface, thereby maintaining mechanical integrity during lithium alloying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal-based anode active materials (Si, Sn) are used to increase charge/discharge capacity, then capacity is improved, but volume expansion during charging/discharging causes cracks and reduces cycle life
Solution Approach 1:
The metal-based anode active material is divided into fine particles with an average diameter of 10 μm or less, and further segmented into domains of 1 μm or less within the coating layer. This segmentation reduces the stress concentration and prevents crack propagation during volume expansion, thereby improving cycle life while maintaining high capacity.
Solution Approach 2:
The metal-based anode active material particles are coated with a coating layer that contains Sn-based domains. The coating layer acts as a protective shell that accommodates the volume expansion of the inner metal particles, preventing structural degradation and maintaining long-term cycling stability.
2Reliability
If alloy of Sn and other metal is used to improve cycle life characteristics, then cycle life is improved, but volume expansion still causes stress and mechanical integrity deteriorates
Solution Approach 1:
The coating layer is designed with Sn-based domains having specific properties (average diameter of 1 μm or less) distributed throughout the coating. This local optimization of the coating structure provides targeted stress relief at the domain level while maintaining overall coating integrity, preventing mechanical failure during repeated charging/discharging cycles.
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
The Sn-based coating layer effectively minimizes mechanical stress and maintains the anode's initial size during charging and discharging, enhancing the cycle life and capacity of lithium secondary batteries.
Implementation Method 1
formed through electroplating
Data Source
AI summary
The present invention relates to an anode active material for a lithium secondary battery, comprising a carbon material, and a coating layer formed on the surface of particles of the carbon material and having a plurality of Sn-based domains having an average diameter of 1 μm or less. The inventive anode active material having a Sn-based domains coating layer on the surface of a carbon material can surprisingly prevent stress due to volume expansion which generates by an alloy of Sn and lithium. Also, the inventive method for preparing an anode active material can easily control the thickness of the coating layer.