Silicon Anode Material with LiF-SiOx Coating for Volume Expansion Control
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Solution Overview
Problem
Existing silicon-based negative electrode materials in secondary batteries suffer from low initial efficiency and excessive volume change during charging and discharging, leading to side reactions with the electrolyte and reduced battery lifespan and safety.
Innovation Solution
A negative electrode active material comprising a carbonaceous matrix with a silicon core coated by an oxide layer of SiOx and a LiF coating, combined with graphene particles, to control volume expansion and improve conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a carbon coating layer is formed on the surface of a silicon-based particle, then the side reaction with electrolyte is reduced, but the volume expansion of silicon-based particle is not effectively controlled
Solution Approach 1:
The patent applies composite materials by creating a multi-layered structure consisting of a silicon core, an oxide layer (SiOx), and a carbonaceous matrix. This composite structure addresses both issues: the oxide layer provides a buffer for volume expansion while the carbonaceous matrix prevents side reactions with the electrolyte, achieving dual functionality that a single carbon coating layer cannot provide.
Solution Approach 2:
The patent employs the nested doll principle by placing the silicon core inside the oxide layer, which is in turn enclosed by the carbonaceous matrix. This nested structure allows each layer to perform its specific function while providing overall protection and volume control for the silicon-based particle during charging and discharging cycles.
2Productivity
If a carbon coating layer is formed on the surface of a silicon-based particle, then the initial efficiency is improved, but the discharge capacity is reduced
Solution Approach 1:
The patent applies local quality by creating different functional zones: the oxide layer provides local volume buffering where needed, while the carbonaceous matrix provides local protection against electrolyte side reactions. This localized functional distribution optimizes both initial efficiency and discharge capacity by placing each material where it is most needed.
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 enhances initial efficiency, discharge capacity, and reduces electrode thickness change, improving capacity retention and stability by facilitating complexation between silicon and graphene particles.
Implementation Method 1
the first particle includes a silicon core, an oxide layer disposed on the silicon core and including SiOx (0≤x≤2)
Implementation Method 2
a coating layer covering at least a portion of the surface of the oxide layer and including LiF
Implementation Method 3
the complexation of a first particle and a second particle may be facilitated by graphene
Data Source
AI summary
The present invention relates to a negative electrode active material including a carbonaceous matrix having a first particle and a second particle, wherein the first particle includes a silicon core, an oxide layer disposed on the silicon core and including SiOx (0<x≤2), and a coating layer covering at least a portion of the surface of the oxide layer and including LiF, and the second particle includes graphene.