SiOx Anode Composite Coating for Stable Aqueous Slurry Processing
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Solution Overview
Problem
Lithium-ion secondary batteries using silicon materials face challenges in achieving stable slurry production and industrial scalability due to low water repellency and instability when modified with Li, leading to reduced cycle performance and capacity.
Innovation Solution
A negative electrode active material comprising SiOx particles with a carbon coating and a composite layer of amorphous metal oxide and metal hydroxide, which enhances water repellency and stability, allowing for improved industrial production and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as a negative electrode active material to improve battery capacity, then the battery capacity increases significantly, but the negative electrode active material expands or shrinks during charging or discharging, making it easy to break particularly near its surface layer
Solution Approach 1:
The patent applies a multi-layer nested structure where silicon particles are embedded within a carbon-containing layer, which is further coated with an aluminum oxide layer. This nested configuration allows the silicon to expand and contract during charging/discharging while being constrained and protected by the surrounding layers, preventing structural breakage while maintaining high capacity
Solution Approach 2:
The patent uses a composite material structure combining silicon, carbon, and aluminum oxide. The silicon provides high capacity, the carbon layer provides structural flexibility and conductivity, and the aluminum oxide layer provides mechanical strength and stability. This composite approach resolves the contradiction between high capacity and structural integrity
2Reliability
If the surface layer of the negative electrode active material breaks, then a new surface is created increasing reaction area, but this causes decomposition reaction of electrolyte and consumes electrolyte, reducing cycle performance
Solution Approach 1:
The patent applies a protective carbon-containing layer and aluminum oxide coating on the silicon particles before they are subjected to electrochemical cycling. This preliminary protective action prevents surface breakage and subsequent electrolyte decomposition during normal operation, maintaining cycle performance while allowing the high capacity of silicon to be utilized
Solution Approach 2:
The carbon-containing layer and aluminum oxide coating act as a cushioning barrier that absorbs and distributes the mechanical stress during silicon expansion and contraction. This beforehand cushioning prevents surface layer breakage and the subsequent harmful electrolyte decomposition reaction, improving cycle performance
3Reliability
If silicon oxide modified by insertion and partial extraction of Li is used to improve cycle retention rate and first efficiency, then these performance metrics improve, but the water repellency is relatively low leading to instability in aqueous slurry
Solution Approach 1:
The patent creates a composite structure where lithium-modified silicon oxide particles are coated with carbon-containing material and further covered with aluminum oxide. This composite structure maintains the electrochemical performance benefits of lithium-modified silicon oxide while the aluminum oxide coating provides hydrophobicity and stability in aqueous slurry, resolving the contradiction between performance and stability
4Reliability
If a carbon coating is formed on silicon oxide particles to improve conductivity and stability, then these properties improve, but additional coating layers increase device complexity
Solution Approach 1:
The patent merges multiple functions into a multi-layer coating structure where the carbon-containing layer provides both conductivity and structural support, while the aluminum oxide layer provides both stability in slurry and additional mechanical protection. This merging of functions into integrated layers improves reliability while managing complexity through functional integration rather than separate independent coatings
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 solution provides a stable and high-capacity non-aqueous electrolyte secondary battery with enhanced cycle retention and first efficiency, preventing gas generation and maintaining integrity during slurry storage.
Implementation Method 1
enhances water repellency and stability
Implementation Method 2
A negative electrode active material comprising SiOx particles with a carbon coating
Implementation Method 3
lithium-ion secondary batteries are easy to reduce the size and increase the capacity and have higher energy density
Data Source
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AI summary
The present invention is a negative electrode active material for a non-aqueous electrolyte secondary battery, including: negative electrode active material particles that contain a silicon compound (SiOx: 0.5 ≤ x ≤ 1.6) containing a Li compound, wherein the silicon compound is at least partially coated with a carbon coating, and at least a part of a surface of the silicon compound, a surface of the carbon coating, or both of them are coated with a composite layer that contains a composite composed of amorphous metal oxide and metal hydroxide. This provides a negative electrode active material for a non-aqueous electrolyte secondary battery that is highly stable in aqueous slurry, having a high capacity, favorable cycle performance and first efficiency.