Silicon-Copper Composite Negative Electrode for Li-Ion Batteries
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Solution Overview
Problem
Current negative electrode active materials using silicon for lithium ion secondary batteries face challenges in achieving high battery capacity per unit mass and cycle characteristics due to large volume changes during charge and discharge, leading to poor performance.
Innovation Solution
A negative electrode active material composed of silicon, copper, and oxygen is developed by pulverizing and mixing silicon with copper oxide or metallic copper and water, resulting in a material with improved cycle characteristics and increased battery capacity, achieved through the formation of fine silicon particles and copper-silicon compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as a negative electrode active material to increase battery capacity, then the theoretical capacity increases from 372 mAh/g to 4,200 mAh/g, but the volume change during charge and discharge reaches approximately 4 times, causing internal strain and particle pulverization that deteriorate cycle characteristics
Solution Approach 1:
The silicon particles are divided into fine particles with a specific surface area of 1.5 m²/g or more, which segments the material into smaller units that can better accommodate volume changes during lithium alloying and de-alloying reactions, reducing internal strain and preventing particle pulverization while maintaining high capacity
Solution Approach 2:
The invention creates a composite structure where silicon particles are combined with a porous coating layer containing silicon oxide and/or silicon nitride, forming a composite material that leverages the high capacity of silicon while the porous coating provides stress relief and structural stability during cycling, improving cycle characteristics
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 resulting material exhibits enhanced cycle characteristics and battery capacity, effectively addressing the limitations of previous silicon-based negative electrode active materials by reducing volume fluctuations and improving stress relaxation during lithium ion absorption and release.
Implementation Method 1
silicon and copper (II) oxide are charged in a pulverization device and pulverized, and simultaneously the pulverized product is mixed
Implementation Method 2
silicon, metallic copper and water are charged in a pulverization device and pulverized, and simultaneously the pulverized product is mixed
Implementation Method 3
silicon is capable of forming an alloy with lithium, and thus has excellent characteristics as a negative electrode material that it may not cause internal short-circuit due to the formation of dendrite on charge and discharge
Data Source
AI summary
A method for producing a negative electrode active material for a lithium ion secondary battery, comprising a step of charging either silicon and copper (II) oxide or silicon and copper metal in a pulverization device, pulverizing either the silicon and copper (II) oxide or silicon and copper metal, and simultaneously mixing either silicon and copper (II) oxide or silicon and copper metal thus pulverized. A negative electrode active material for a lithium ion secondary battery is produced by the method.