Metal Carbon Composite Negative Electrode for Battery Cycle Life
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Solution Overview
Problem
Existing nonaqueous electrolyte solution batteries face challenges in maintaining charge-and-discharge cycle characteristics due to volume changes in metal-based active materials, leading to cracking and sliding, which reduces the battery's lifespan.
Innovation Solution
A negative electrode comprising a metal carbon composite material with a porous carbon structure, where the metal material is arranged on the surface of the porous carbon material, including inner surfaces of cavities, providing a stable electric conduction route and cushioning for volume changes, thus preventing cracking and sliding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal material such as Si or Sn is used as negative electrode active material to achieve higher capacity, then battery capacity is improved, but volume change during charging and discharging causes crack or sliding leading to shortened cycle life
Solution Approach 1:
The patent employs a porous carbon material as the matrix structure to accommodate metal particles. The porous structure provides void spaces that can absorb the volume expansion of metal materials during lithium alloying reactions, preventing crack formation and maintaining electrode integrity over multiple charge-discharge cycles while preserving high capacity.
Solution Approach 2:
The patent creates a composite structure combining metal particles (Si, Sn, or their alloys) with carbon material. The metal particles provide high lithium storage capacity while the carbon matrix provides structural stability and electrical conductivity. This composite approach allows the metal to undergo volume changes without compromising the overall electrode structure, thus maintaining both high capacity and long cycle life.
2Stability of the object's composition
If porous structure is created by depositing polymer particles and eliminating them to absorb volume expansion, then volume change is accommodated, but electrode itself becomes weak
Solution Approach 1:
Instead of using porous structures created by removing polymer particles (which weakens the electrode), the patent uses a inherently porous carbon material as the matrix. This carbon-based porous structure provides both the necessary void spaces for volume accommodation and maintains sufficient mechanical strength and structural integrity for electrode operation.
Solution Approach 2:
The patent changes the approach to creating porous structure from a post-processing removal method (eliminating polymer particles) to using a pre-formed porous carbon material. This parameter change in the structural design allows the electrode to maintain both volume stability and mechanical strength simultaneously.
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 metal carbon composite material enhances the charge-and-discharge cycle characteristics by maintaining contact and securing the electric conduction route, even with volume changes, resulting in improved battery performance and extended lifespan.
Implementation Method 1
a metal material to reversibly store or emit lithium ion... In this case, the active material may have a crack or sliding
Implementation Method 2
Volume expansion generated in a charging time can be absorbed since many uniform communication apertures are formed
Implementation Method 3
carbon nano-fiber having aspect ratio of 10 or more and a metal-based active material... electric conduction route can be secured
Data Source
AI summary
A negative electrode used for a nonaqueous electrolyte solution battery having nonaqueous electrolyte solution containing lithium ion includes a metal carbon composite material. The metal carbon composite material has a porous carbon material having cavities, and a metal material made of metal to reversibly store or emit lithium ion. The metal material is arranged on a surface of the porous carbon material including inner surfaces of the cavities. The porous carbon material has a mass of 1-65 mass % when the metal carbon composite material is defined to have a mass of 100 mass %.