Stabilized Carbon Anode with Group IV Coating
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Solution Overview
Problem
Lithium batteries with carbon-based anodes face issues of reduced cycle and calendar life due to exfoliation and physical degradation, leading to instability of the solid electrolyte interface (SEI) layer, which limits their performance in high-energy applications.
Innovation Solution
A thin layer of a Group IV element, such as silicon, germanium, or tin, is deposited on the carbon anode's electrolyte contacting surfaces using thin film techniques like glow discharge or sputtering to stabilize the SEI layer and prevent exfoliation, enhancing the anode's integrity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon-based anodes are used in lithium batteries, then charge capacity and energy density are improved, but cycle life and calendar life are reduced due to exfoliation and physical degradation
Solution Approach 1:
The patent applies composite materials by combining carbon-based anode material with a coating layer of silicon oxide, silicon nitride, or other protective materials. This composite structure maintains the high charge capacity of carbon while the coating layer prevents exfoliation and physical degradation, thereby resolving the contradiction between charge capacity and cycle life.
Solution Approach 2:
The patent changes the surface properties of the carbon anode by applying thin film coatings with specific chemical compositions (silicon oxide, silicon nitride, etc.). This parameter change in surface chemistry stabilizes the SEI layer and prevents degradation, allowing the battery to maintain both high charge capacity and extended cycle life.
2Use of energy by moving object
If carbon-based anodes are used in lithium batteries, then energy density is improved, but calendar life is reduced due to SEI layer instability
Solution Approach 1:
The patent creates a composite anode structure where carbon material is combined with a protective coating layer. This composite structure maintains the high energy density of carbon while the coating stabilizes the SEI layer over time, preventing degradation and extending calendar life.
Solution Approach 2:
The patent applies thin film coatings (silicon oxide, silicon nitride, etc.) on the carbon anode surface. These thin films act as protective shells that stabilize the SEI layer, preventing its degradation over time while maintaining the high energy density of the underlying carbon structure.
3Reliability
If thin film deposition techniques are used to coat carbon anodes, then SEI layer stability is improved, but manufacturing complexity is increased
Solution Approach 1:
The patent replaces complex mechanical coating processes with thin film deposition techniques that utilize physical vapor deposition or chemical vapor deposition. These methods deposit protective layers at controlled rates and temperatures, achieving stable SEI layers through controlled material deposition rather than mechanical means, thereby managing manufacturing complexity through process control.
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 stabilized SEI layer significantly increases the cycle and calendar life of lithium batteries by preventing physical degradation, maintaining the benefits of carbon-based anodes while improving their reliability and capacity.
Implementation Method 1
During the initial charging of the battery, the surface of the anode can react with lithium ions and components of the electrolyte to form a layer of material referred to as a 'solid electrolyte interface' (SEI) layer
Implementation Method 2
The anode further includes a layer of a Group IV element or Group IV element-containing substance disposed on the electrolyte contacting surfaces of the body of carbon
Implementation Method 3
A thin layer of a Group IV element, such as silicon, germanium, or tin, is deposited on the carbon anode's electrolyte contacting surfaces using thin film techniques like glow discharge or sputtering
Data Source
Figure 1~2
AI summary
Disclosed is an anode for a lithium battery comprising a body of carbon, such as graphitic carbon, having a layer of a Group IV element or Group IV element-containing substance disposed upon its electrolyte contacting surface. Further disclosed is an anode comprising a body of carbon having an SEI layer formed thereupon by interaction of a layer of Group IV element or Group IV element-containing substance with an electrolyte material during the initial charging of the battery.