Layered Silicon-Graphite Anode Structure for Quick-Charge Adhesion
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Solution Overview
Problem
Lithium secondary batteries face limitations in thermal stability and quick charging performance due to the characteristics of graphite-based anodes, which hinder the achievement of desired charging and discharging characteristics.
Innovation Solution
An anode structure comprising a first layer of natural graphite and artificial graphite, and a second layer containing a silicon-based compound, with specific mixing ratios and binders, to enhance adhesion and thermal stability, and improve quick charging capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If natural graphite is used in the anode, then adhesion to current collector is improved, but quick charging performance deteriorates
Solution Approach 1:
The anode is divided into multiple layers with different compositions: a first layer containing natural graphite and artificial graphite for adhesion, and a second layer containing silicon-based compound and artificial graphite for quick charging performance. This segmentation allows each layer to optimize for its specific function.
Solution Approach 2:
Different regions of the anode are assigned different material compositions tailored to local requirements: the first layer near the current collector uses natural graphite for adhesion, while the second layer uses silicon-based compound for enhanced lithium ion diffusion and quick charging.
2Reliability
If graphite-based anode is used, then electrochemical reaction potential close to lithium metal is achieved, but thermal stability is insufficient
Solution Approach 1:
The anode uses a composite structure combining graphite-based materials (for electrochemical performance) with silicon-based compounds and ceramic coatings (for thermal stability). This composite approach allows simultaneous achievement of electrochemical reaction potential close to lithium metal and improved thermal stability.
3Speed
If multi-layered electrode is used to improve quick charging, then stability is enhanced, but performance is still limited by graphite characteristics
Solution Approach 1:
The invention changes the material composition parameter by introducing silicon-based compounds with higher lithium ion diffusion rates and larger capacity into the second layer, overcoming the inherent limitations of graphite while maintaining the multi-layered structure for stability.
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 proposed anode structure significantly improves thermal stability and quick charging characteristics of lithium secondary batteries by optimizing the mixing ratios and layer thickness, ensuring better adhesion and reaction efficiency during charging and discharging.
Implementation Method 1
a second anode active material layer formed on the first anode active material layer and containing a silicon-based compound together with artificial graphite
Implementation Method 2
a diffusion rate of lithium ions in the active material should be fast
Implementation Method 3
electrochemical reaction potential should be close to a lithium metal, reaction reversibility with lithium ions should be high
Data Source
AI summary
A method for manufacturing an anode for a lithium secondary battery includes applying a slurry for forming a first anode active material layer on at least one surface of an anode current collector; applying a slurry for forming a second anode active material layer on the first anode active material layer; and drying. The first anode active material layer contains a mixture of natural graphite and artificial graphite in a weight ratio of 13 to 34:66 to 87 as an anode active material and a first binder respectively, and the second anode active material layer contains a mixture of artificial graphite and a silicon-based compound in a weight ratio of 91 to 99:1 to 9 as the anode active material and a second binder respectively.