Gradient SiOx Silicon Anode With Carbon Shell for Stable Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing silicon-based anode materials for lithium-ion batteries suffer from high surface activity leading to electrolyte decomposition and unstable electrochemical performance, resulting in unsatisfactory cycling performance and safety concerns due to volume changes and internal stress.
Innovation Solution
A silicon-based anode material with a core-shell structure, where the core consists of SiOx with dispersed silicon microcrystals and a carbon shell layer, is developed. The silicon microcrystals' distribution density decreases from the surface to the center, and a carbon layer is formed to enhance conductivity and act as a buffer, mitigating volume expansion and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anode material is used to achieve high theoretical specific capacity, then capacity density is improved, but volume change exceeds 300% causing powdering and peeling which worsens cycle stability
Solution Approach 1:
The silicon-based anode material is divided into microcrystals dispersed within SiOx matrix, preventing monolithic volume expansion. The gradient distribution of silicon microcrystals (higher density at surface, lower at center) further segments the structure to manage stress during lithium insertion/extraction cycles.
Solution Approach 2:
Silicon microcrystals are nested within the SiOx matrix, forming a composite structure where the SiOx provides a stable framework that accommodates silicon volume changes. This nested configuration allows the high-capacity silicon to function while being constrained by the stable SiOx container.
Solution Approach 3:
The anode material combines silicon microcrystals with SiOx matrix to create a composite structure. This composite approach leverages the high capacity of silicon while utilizing the volume-stabilizing properties of SiOx, achieving both high specific capacity and improved cycle stability.
2Quantity of substance
If silicon-based anode material with high surface activity is used to achieve high capacity, then electrochemical activity is improved, but electrolyte decomposition occurs causing safety issues and unstable performance
Solution Approach 1:
The SiOx matrix acts as an intermediary between the silicon microcrystals and the electrolyte, reducing direct contact and interaction. This intermediary layer moderates the surface activity of silicon, preventing excessive reaction with the electrolyte while still allowing lithium ion transport.
Solution Approach 2:
The SiOx matrix creates a chemically inert environment around the reactive silicon microcrystals, protecting them from direct interaction with the electrolyte. This inert barrier prevents electrolyte decomposition while maintaining lithium ion conductivity through the matrix.
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
This structure effectively inhibits volume expansion, improves cycling stability, and enhances the electrochemical performance of the anode, resulting in a lithium-ion battery with high capacity, long cycle life, and reliable safety.
Implementation Method 1
during charging and discharging, the volume change of silicon reaches more than 300%
Implementation Method 2
the internal stress generated by the dramatic volume change easily leads to powdering and peeling of the electrode
Data Source
AI summary
A silicon-based anode material, including a silicon-based core; and a shell layer arranged on the silicon-based core, the silicon-based core comprises SiOx and silicon microcrystals dispersed in the SiOx, where 0.9≤x≤1.3; and a distribution density of the silicon microcrystals gradually decreases along a direction from a surface of the silicon-based core to the center of the silicon-based core, the shell layer includes a carbon layer. The silicon-based anode material has high capacity and low volume expansion effect, and the battery capacity and cycle performance can be improved in the applications in non-aqueous electrolyte secondary batteries. A preparation method for a silicon-based anode material for lithium-ion batteries.