Porous Carbon-Silicon Anode Coating for Longer Battery Cycle Life
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Solution Overview
Problem
Existing secondary batteries face issues with volume expansion of silicon-based anode active materials leading to cracks and exposure to electrolyte, which degrade cycle life and output characteristics.
Innovation Solution
A composite anode active material comprising carbon-based particles with silicon-containing coatings and controlled pore structures that accommodate volume expansion, reducing internal resistance and suppressing gas generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based anode active material is used to increase capacity, then energy density is improved, but volume expansion causes cracks and exposure to electrolyte degrading cycle life
Solution Approach 1:
The silicon-containing coating is formed inside the pores of the carbon-based particles, creating a nested structure where silicon is contained within the carbon matrix. This prevents volume expansion cracks from propagating while maintaining electrical contact, thereby improving both energy density and cycle life
Solution Approach 2:
The carbon-based particle structure acts as a flexible shell that can accommodate the volume expansion of silicon during lithiation/delithiation cycles. The porous carbon matrix provides mechanical flexibility and structural integrity, preventing crack formation and maintaining electrode integrity over multiple cycles
2Use of energy by moving object
If silicon content is increased to improve capacity, then energy density is improved, but gas generation from side reactions with electrolyte increases
Solution Approach 1:
The carbon-based particles provide an inert environment that isolates the silicon-containing coating from direct contact with the electrolyte. This prevents harmful side reactions and gas generation while allowing lithium ion insertion/extraction, thereby maintaining high energy density without increased gas evolution
3Reliability
If silicon-containing coating is formed on carbon-based particles to accommodate volume expansion, then cycle life is improved, but internal resistance increases
Solution Approach 1:
The silicon-containing coating is localized specifically within the pores of the carbon-based particles rather than forming a continuous outer layer. This localized placement provides volume expansion accommodation at the necessary locations while maintaining good electrical contact pathways through the conductive carbon matrix, thus improving cycle life without significantly increasing internal resistance
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 composite anode material enhances durability, improves cycle life and output characteristics by preventing cracks and reducing internal resistance, while maintaining high-temperature stability.
Implementation Method 1
volume expansion of silicon-based anode active materials leading to cracks
Implementation Method 2
controlled pore structures that accommodate volume expansion, reducing internal resistance
Implementation Method 3
gas generation caused by side reactions between the anode active material and the electrolyte
Data Source
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AI summary
An anode active material for a lithium secondary battery based on some embodiments of the disclosed technology includes composite particles that include: carbon-based particles including pores; and a silicon-containing coating formed on a surface of the carbon-based particles, wherein a weight increase start temperature of the composite particle, measured by thermogravimetric analysis (TGA) at a heating rate of 10 °C/min, is from 440 °C to 580 °C.