Silicon Anode Metal Oxide Coating for Battery Stability
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Solution Overview
Problem
Lithium-ion batteries with tin or silicon anode materials face challenges in maintaining high energy density and charge-discharge efficiency due to the decomposition of electrolyte solutions and poor cycle characteristics, especially when the anode surface is coated with thick oxide films.
Innovation Solution
An anode material is developed with a thin coating of metal oxide (0.01 wt % to 10 wt %) on the surface of active silicon or tin portions, enhancing chemical stability and allowing smooth lithium insertion and extraction, while maintaining high energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick oxide film is formed on the anode surface by sol-gel method, then chemical stability is improved, but volume energy density and charge-discharge efficiency decline
Solution Approach 1:
The patent changes the critical parameter of oxide film thickness from conventional thick coatings (formed by sol-gel method) to an ultra-thin layer of 1-100 nm. This parameter change resolves the contradiction by providing sufficient chemical stability while minimizing volume occupation, thereby maintaining high energy density and charge-discharge efficiency
Solution Approach 2:
The patent employs an ultra-thin oxide film as a protective shell on the anode surface. This thin film approach provides the necessary chemical stability and protection while occupying minimal volume, thus avoiding the energy density penalty associated with thicker oxide coatings
2Reliability
If a thick oxide film is formed on the anode surface, then chemical stability is improved, but charge-discharge efficiency declines
Solution Approach 1:
The patent changes the oxide film thickness parameter to 1-100 nm, which is sufficiently thin to allow rapid lithium ion diffusion and maintain high charge-discharge efficiency, while still providing adequate chemical stability and protection against electrolyte decomposition
Solution Approach 2:
The ultra-thin oxide film acts as an intermediary layer that mediates between the anode active material and the electrolyte. It provides chemical stability and protection without creating a significant barrier to lithium ion transport, thus maintaining high charge-discharge efficiency
3Quantity of substance
If tin or silicon is used as anode active material, then theoretical capacity is improved, but electrolyte decomposition occurs and cycle characteristics deteriorate
Solution Approach 1:
The patent uses an ultra-thin oxide film as a protective shell on tin or silicon anodes. This thin film prevents direct contact between the highly reactive anode material and the electrolyte, stopping decomposition reactions while maintaining structural integrity during charge-discharge cycles, thus improving cycle characteristics
Solution Approach 2:
The oxide film serves as an intermediary barrier between the high-capacity but chemically unstable tin/silicon anode and the electrolyte. It prevents harmful direct reactions while allowing ionic transport, thereby enabling the high theoretical capacity materials to achieve good cycle 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 anode material achieves superior charge-discharge efficiency and capacity retention by preventing electrolyte decomposition and optimizing lithium ion mobility, thus improving battery performance.
Implementation Method 1
a coating portion of a metal oxide arranged on a part of a surface of the active portion... chemical stability can be improved
Implementation Method 2
an electrode reactant can be smoothly inserted and extracted... lithium insertion and extraction
Data Source
AI summary
An anode material capable of obtaining a high capacity and superior charge-discharge efficiency, and an anode and a battery using the anode material are provided. An anode includes an anode material including an active portion including at least one of silicon and tin as an element and a coating portion of a metal oxide arranged on a part of a surface of the active portion. The ratio of the coating portion to the active portion is within a range from 0.01 wt % to 10 wt % inclusive. Thereby, a high capacity and superior charge-discharge efficiency can be obtained.