Solid-State Battery Anode Conductive Network for Resistance Stability
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Solution Overview
Problem
Conventional all-solid-state batteries experience a high resistance increase ratio after long-term use, leading to battery deterioration.
Innovation Solution
The use of an alloy-based active material anode combined with two types of fibrous carbons, where the first fibrous carbon has a larger fiber diameter and the second fibrous carbon has a smaller fiber diameter, with a specific ratio and proportion to form both broad and minute paths, effectively suppressing resistance increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alloy-based active material is used for anode, then battery capacity is improved, but resistance increase ratio becomes high after long-term use
Solution Approach 1:
The conductive aid is segmented into two distinct types: spherical carbon particles (150 nm or less) and fibrous carbon (10 μm or more). This segmentation allows each component to fulfill specific functions - spherical carbon provides minute paths covering active material particles, while fibrous carbon creates broad paths connecting cracks, thereby resolving the resistance increase issue while maintaining high capacity
Solution Approach 2:
The invention uses a composite conductive aid system combining two different carbon forms (spherical and fibrous) with specific weight ratios (80/20 to 50/50). This composite approach leverages the complementary strengths of both carbon types to simultaneously achieve high battery capacity and low resistance increase ratio, overcoming the limitations of using either carbon type alone
2Area of stationary object
If fibrous carbon with large diameter is used, then broad paths are formed, but minute paths to cover all active material particles cannot be formed
Solution Approach 1:
The conductive network is segmented into two functional components: fibrous carbon providing broad path areas for crack connection, and spherical carbon providing minute paths for comprehensive particle coverage. This segmentation resolves the contradiction between forming broad paths and achieving fine particle coverage
3Manufacturing precision
If spherical carbon is used, then minute paths are formed, but broad paths to connect cracks cannot be formed
Solution Approach 1:
The conductive system is divided into two specialized components: spherical carbon for creating minute paths that cover active material particles, and fibrous carbon for establishing broad paths that connect cracks. This functional segmentation allows both path types to coexist and complement each other
Solution Approach 2:
A composite conductive aid system is created by combining spherical carbon and fibrous carbon in specific proportions. The spherical carbon component ensures comprehensive particle coverage, while the fibrous carbon component provides robust crack connectivity, achieving both fine and coarse conductive networks simultaneously
Data Source
AI summary
Provided is an all-solid-state battery capable of suppressing a rise in the resistance increase ratio thereof. The all-solid-state battery includes an anode active material layer containing an alloy-based active material, a first fibrous carbon, and a second fibrous carbon, wherein when a fiber diameter of the first fibrous carbon is defined as A, and a fiber diameter of the second fibrous carbon is defined as B, the ratio of A to B is 10 to 300, and when the proportion (wt %) of the first fibrous carbon to the alloy-based active material is defined as X, and the proportion (wt %) of the second fibrous carbon to the alloy-based active material is defined as Y, the proportion ({Y/(X+Y)}×100%) of the contained second fibrous carbon to a total of the first fibrous carbon and the second fibrous carbon is 0.5% to 10%.