LiF-Coated Silicon-Carbon Anode Material for Expansion Control
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Solution Overview
Problem
Existing negative electrode active materials using silicon-based particles suffer from low initial efficiency and volume expansion during charging and discharging, leading to side reactions with the electrolyte and reduced battery lifespan and stability.
Innovation Solution
A negative electrode active material comprising a spherical carbon-based particle with a carbon layer, a silicon core covered by an oxide layer of SiOx, and a coating layer of LiF, which stabilizes the volume expansion and prevents side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a silicon-based particle is used as negative electrode active material, then discharge capacity is improved, but volume expansion occurs during charging and discharging
Solution Approach 1:
The patent applies nested structure by placing the silicon-based particle inside a carbon-based particle. The silicon core is surrounded by an oxide layer, then a carbon layer, and finally embedded within a larger carbon-based particle. This nested configuration allows the silicon to expand during charging while contained within the carbon matrix, preventing volume expansion issues while maintaining high discharge capacity.
Solution Approach 2:
The patent creates a composite material structure combining silicon-based particles with carbon-based particles. The composite consists of an inner silicon core with oxide layer, surrounded by a carbon layer, and embedded in an outer carbon-based particle matrix. This composite structure leverages the high capacity of silicon while using carbon to constrain volume changes and provide structural stability.
2Quantity of substance
If a silicon-based particle is used as negative electrode active material, then discharge capacity is improved, but side reaction with electrolyte increases
Solution Approach 1:
The patent introduces multiple intermediary layers between the silicon-based particle and the electrolyte. First, an oxide layer is formed on the silicon surface, then a carbon layer is deposited over the oxide layer. These intermediary layers act as protective barriers that prevent direct contact between the reactive silicon and the electrolyte, thereby reducing side reactions while allowing lithium ion transport.
Solution Approach 2:
The composite structure with multiple layers (silicon core, oxide layer, carbon layer, and outer carbon-based particle) creates a protective barrier system. This composite material approach allows the high-capacity silicon to be isolated from the electrolyte, preventing harmful side reactions while maintaining electrochemical performance.
3Quantity of substance
If a silicon-based particle is used as negative electrode active material, then initial efficiency is low, but capacity can be increased
Solution Approach 1:
The nested structure with silicon core inside carbon-based particle provides a stable framework that improves initial efficiency. The carbon matrix ensures good electrical contact and structural integrity from the first cycle, while the protected silicon surface reduces initial electrolyte consumption, thereby improving initial efficiency without sacrificing capacity.
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 improves initial efficiency and discharge capacity by controlling volume expansion and reducing side reactions, enhancing the overall performance and stability of the battery.
Implementation Method 1
an oxide layer disposed on the silicon core and including SiOx (0≤x≤2), which covers the entire surface of the silicon core, thereby preventing contact between the silicon core and an electrolyte, and thereby stabilizing a volume expansion
Implementation Method 2
a coating layer covering at least a portion of the oxide layer and including LiF... a side reaction between a negative electrode active material and an electrolyte and the volume expansion of the negative electrode active material may be effectively controlled
Implementation Method 3
a carbon layer disposed on the spherical carbon-based particle and including a nano-particle... the initial efficiency and discharge capacity of a battery may be improved
Data Source
AI summary
The present invention relates to a negative electrode active material including a spherical carbon-based particle, and a carbon layer disposed on the spherical carbon-based particle and including a nano-particle, wherein the nano-particle has 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.