Silicon-Carbon Composite Anode With Graphite and CNTs for Cycle Stability
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Solution Overview
Problem
Existing electrochemical energy storage devices, particularly Li-ion batteries, face challenges in achieving good cycling stability and long lifetime, which are crucial for market acceptance, especially in electric vehicles.
Innovation Solution
An anode comprising a silicon-carbon composite material with specific weight percentages, anisometric flake graphite, and carbon nanotubes, along with a binder, is used to enhance electrochemical properties, including improved cycle stability and charging times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-carbon composite material is used to increase energy density, then charging capacity is improved, but cycle stability deteriorates
Solution Approach 1:
The patent uses a composite anode structure combining silicon-carbon composite material (45-96 wt.%) for high capacity with graphite (4-21 wt.%) and carbon nanotubes (0.1-2 wt.%) for structural stability. The carbon matrix encapsulates silicon particles, preventing volume expansion damage during cycling, while graphite provides stable lithium insertion/extraction sites. This composite approach resolves the contradiction by integrating the high capacity advantage of silicon with the stability advantage of carbon materials.
2Productivity
If charging speed is increased to reduce charging time, then productivity is improved, but cycle stability deteriorates
Solution Approach 1:
The patent applies different carbon materials with different functions in specific proportions: amorphous carbon provides fast ion transport pathways for high charging speed, while crystalline graphite provides stable structural framework for cycle stability. The carbon nanotubes (0.1-2 wt.%) specifically address conductivity needs. This localized functional distribution allows the anode to simultaneously achieve fast charging and maintain cycle stability.
Data Source
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AI summary
The present invention relates to an anode (110) for an electrochemical energy storage device (100), at least comprising - a silicon-carbon composite material (10) in the amount of ≥ 45 wt.-% to ≤ 96 wt.-%, relating to the anode (110), - an anisometric flake graphite in the amount of ≥ 2 wt.-% to ≤ 45 wt.-%, relating to the anode (110); - carbon nanotubes in the amount of > 0 wt.-% to < 1 wt.-%, relating to the anode (110); and - a binder, in particular a polymer binder, in the amount of 0.5 wt.-% to 4 wt.-%, relating to the anode (110).