Silicon-Coated Fiber Anode Mesh for Swelling-Stable Li-Ion Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Secondary batteries, particularly lithium-ion batteries, face insufficient initial capacity, swelling, and cyclability characteristics due to limitations in the configuration of their negative electrodes.
Innovation Solution
A negative electrode configuration featuring first fiber parts made of carbon with an average diameter between 10 nm and 8000 nm, second fiber parts with diameters between 1 nm and 300 nm, and covering parts with silicon, forming a three-dimensional mesh structure with voids, eliminating the need for a metal current collector and optimizing the void rate between 40% and 70% volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional negative electrode configuration is used, then the battery structure is simple, but the initial capacity characteristic, swelling characteristic, and cyclability characteristic are insufficient
Solution Approach 1:
The negative electrode is segmented into multiple functional components: first fiber parts forming a three-dimensional mesh structure, covering parts with silicon-containing materials on the fiber surfaces, and second fiber parts coupled to the covering parts. This segmentation allows each component to perform its specific function optimally, improving initial capacity, swelling characteristic, and cyclability while maintaining structural integrity.
Solution Approach 2:
The negative electrode employs composite materials including carbon-containing fibers (first and second fiber parts) and silicon-containing covering parts. This composite structure combines the electrical conductivity and structural stability of carbon with the high capacity potential of silicon, resolving the contradiction between performance improvement and structural complexity.
2Reliability
If the void rate is increased to improve swelling characteristic, then the cyclability improves, but the density and energy density may decrease
Solution Approach 1:
The negative electrode utilizes a porous three-dimensional mesh structure formed by coupled first fiber parts with controlled void spaces. This porous architecture provides buffer space for silicon expansion during lithiation while maintaining electrical connectivity through the carbon fiber network, achieving improved swelling characteristic and cyclability without excessive void rate that would reduce energy density.
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
This configuration enhances the initial capacity, swelling characteristics, and cyclability of secondary batteries while reducing weight and increasing gravimetric energy density by forming a dense electrically conductive network and mitigating internal stress through the voids.
Implementation Method 1
The first fiber parts each include carbon as a constituent element... form a three-dimensional mesh structure having the voids
Implementation Method 2
a swelling characteristic of the secondary battery
Implementation Method 3
The negative electrode has a void rate that is greater than or equal to 40 vol % and less than or equal to 70 vol %
Data Source
AI summary
A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The negative electrode includes first fiber parts, covering parts, and second fiber parts, and has voids. The first fiber parts are coupled to each other to thereby form a three-dimensional mesh structure having the voids. The first fiber parts each include carbon as a constituent element. The covering parts each cover a surface of corresponding one of the first fiber parts, and each include silicon as a constituent element. At least some of the second fiber parts are each coupled to a surface of any of the covering parts. The second fiber parts each include carbon as a constituent element. The first fiber parts have an average fiber diameter that is greater than or equal to 10 nm and less than or equal to 8000 nm. The second fiber parts have an average fiber diameter that is greater than or equal to 1 nm and less than or equal to 300 nm. The negative electrode has a void rate that is greater than or equal to 40 vol % and less than or equal to 70 vol %.