Composite Anode Active Material for Lithium Battery
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Solution Overview
Problem
Lithium batteries face challenges with carbonaceous materials having low battery capacity and lifespan due to silicon oxide layer formation and high volume change during charging and discharging, which affects the efficiency and durability of silicon-containing anode active materials.
Innovation Solution
A composite anode active material is developed, comprising a carbonaceous material, a metal alloyable with lithium, and a silicon coating layer formed through chemical vapor deposition, which enhances capacity and lifespan by reducing stress and maintaining a stable structure during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon particles are used as anode active material to achieve high discharge capacity, then battery capacity is improved, but volume change during charging and discharging increases causing cracks and deteriorated lifespan characteristics
Solution Approach 1:
The patent applies nesting by placing silicon particles inside a porous carbonaceous material matrix. The carbonaceous material acts as a container that accommodates the silicon particles, providing structural support and preventing cracks during volume changes. This nested structure allows the silicon to expand and contract without compromising the overall electrode integrity, thus maintaining lifespan characteristics while preserving high capacity.
Solution Approach 2:
The patent employs a porous carbonaceous material as a flexible shell surrounding the silicon particles. This carbon shell is designed to be mechanically flexible enough to accommodate the 3.7-fold volume expansion of silicon during lithiation while maintaining structural integrity. The porous structure of the carbon shell also allows for buffer space during expansion, preventing crack formation and maintaining electrode stability over charge-discharge cycles.
2Quantity of substance
If ball-milled Si particles are used to achieve high electrical capacity, then battery capacity is improved, but silicon oxide layers form on surfaces reducing initial efficiency
Solution Approach 1:
The patent applies preliminary action by pre-forming a porous carbonaceous material matrix before introducing silicon particles. This carbon matrix is prepared in advance with controlled porosity and surface properties that prevent silicon oxide layer formation. By having the protective carbon structure ready beforehand, the silicon particles are immediately protected upon contact, preventing oxidation and maintaining high initial efficiency while preserving the desired electrical capacity.
3Duration of action of stationary object
If graphite is used as anode active material to achieve structural stability, then lifespan characteristics are improved, but battery capacity is reduced due to porous carbon structure
Solution Approach 1:
The patent applies composite materials by combining silicon particles with porous carbonaceous material to create a hybrid anode structure. The carbon component provides structural stability and long lifespan characteristics, while the silicon component contributes high electrical capacity. The synergistic combination of these two materials in a composite structure allows the electrode to simultaneously achieve both durability and high capacity, overcoming the limitations of using either material alone.
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 active material achieves high initial efficiency and excellent lifespan characteristics by uniformly distributing silicon particles and reducing volume expansion, leading to improved capacity and rate capability.
Implementation Method 1
forming a silicon coating layer on a surface of the composite anode active material precursor, wherein the forming of the silicon coating layer is performed by depositing silicon through chemical vapor deposition (CVD) of a silane gas
Data Source
AI summary
Provided is a composite anode active material including: a carbonaceous material; a metal alloyable with lithium, located on a surface of the carbonaceous material; and a silicon coating layer located on a surface of the carbonaceous material, on a surface of the metal alloyable with lithium, or a combination thereof.