SiOC Composite Anode Material for Lithium-Ion Batteries
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Solution Overview
Problem
Conventional graphite anode materials in lithium-ion batteries have low theoretical specific capacity, and silicon-based alternatives suffer from volume expansion issues leading to performance degradation during charge/discharge cycling, resulting in insufficient electrochemical performance for high-energy applications.
Innovation Solution
A silicon oxycarbide (SiOC) composite material in microparticulate form is developed, comprising an amorphous or crystallized silicon-enriched SiOC matrix with a core/coating structure, where the core is formed of amorphous SiOC and coated with an amorphous carbon layer, offering improved cycle durability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anode material is used to replace graphite, then theoretical specific capacity is improved, but volume expansion occurs leading to performance degradation
Solution Approach 1:
The patent changes the chemical composition parameters by forming silicon oxycarbide (SiOC) with specific Si:O:C ratios instead of using pure silicon. This compositional modification reduces the volume expansion issue while maintaining high capacity, achieving 400-600 mAh/g with improved cycling stability
Solution Approach 2:
The invention creates a composite material structure where silicon is chemically bonded with oxygen and carbon to form SiOC. This composite approach combines the high capacity benefit of silicon with the structural stability of oxycarbide, preventing the volume expansion problems of pure silicon
2Reliability
If graphite anode material is used, then structural stability is maintained, but theoretical specific capacity is limited
Solution Approach 1:
The patent modifies the capacity parameter by transitioning from graphite's layered structure to SiOC's amorphous network with different lithium storage mechanisms, achieving 400-600 mAh/g compared to graphite's 372 mAh/g limitation while maintaining structural integrity
3Temperature
If high pyrolysis temperature is used to prepare SiOC material, then crystalline SiC phase is formed, but electrochemical performance degrades
Solution Approach 1:
The patent optimizes the temperature parameter by conducting pyrolysis at 700-900°C instead of higher temperatures. This temperature control prevents the formation of crystalline SiC phase, maintaining the amorphous SiOC structure with superior electrochemical performance and lithium storage capacity
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 SiOC composite material achieves superior reversible capacity and cycle durability, maintaining high initial capacity through multiple charge/discharge cycles, with an average capacity exceeding 700 mAh/g, and is produced through a simple and industrially viable method.
Implementation Method 1
pyrolysing the product of step (i) to yield an amorphous SiOC matrix with Si ranging from 20 wt % to 60 wt %, O from 20 wt % to 40 wt % and C from 10 wt % to 50 wt %
Implementation Method 2
pyrolysing said coated particles to obtain the carbon coating
Data Source
AI summary
A SiOC composite material in microparticulate form, wherein the microparticles are formed, in whole or in part, of an amorphous SiOC matrix with Si ranging from 20 wt % to 60 wt %, O from 20 wt % to 40 wt % and C from 10 wt % to 50 wt %, based on the total weight of the SiOC matrix, wherein amorphous or crystallized silicon particles are embedded within the SiOC matrix and wherein the microparticles are of core/coating structure with a core formed of the amorphous SiOC matrix and coated with at least one amorphous carbon layer; and to a method for producing such SiOC composite material. It also relates to an electrode active material, an electrode and a battery, especially a lithium-ion battery, including the aforementioned SiOC composite material.