Low Fracture Strength Carbon for Solid Battery Moldability
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Solution Overview
Problem
Lithium ion secondary batteries face safety issues due to heat generation and ignition risks associated with high active material content and organic solvents in their electrolytes, while existing all-solid-state batteries require improved moldability and electrode material selection for enhanced performance.
Innovation Solution
The use of carbon materials with fracture strengths of 100 MPa or less as electrode active materials in all-solid-state secondary batteries, combined with sulfide-based lithium ion-conducting solid electrolytes, such as sulfide glass and sulfide glass ceramics, to achieve better moldability and battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon materials with high fracture strength are used as electrode active materials, then the structural integrity and durability of the battery are improved, but the moldability during powder compaction deteriorates
Solution Approach 1:
The invention changes the physical parameter of carbon particles by controlling their fracture strength to be 100 MPa or less. This parameter change enables the carbon particles to be sufficiently compacted during powder compaction to achieve good moldability, while still maintaining adequate structural integrity for battery operation.
2Use of energy by moving object
If the content of active material is increased to achieve high energy density, then the energy capacity of the battery is improved, but the safety risk due to heat generation and ignition increases
Solution Approach 1:
The invention changes the chemical composition parameter of the electrolyte by using inorganic solid electrolytes (such as sulfide-based electrolytes like Li2S-P2S5 system) instead of organic solvents. This parameter change eliminates the combustion risk associated with organic solvents while maintaining high ion conductivity, thereby enabling high energy density without proportional increase in safety risks.
3Reliability
If inorganic solid electrolytes are used to eliminate organic solvents and improve safety, then the safety against ignition and liquid leakage is improved, but the moldability and manufacturing complexity increase
Solution Approach 1:
The invention uses composite materials consisting of carbon particles (with controlled fracture strength of 100 MPa or less) combined with inorganic solid electrolytes. This composite structure enables both the safety benefits of inorganic electrolytes and the manufacturability achieved through optimized carbon particle properties, resolving the contradiction between safety and ease of manufacture.
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 results in all-solid-state secondary batteries with improved moldability, high capacity, and excellent rate characteristics, reducing the risk of ignition and liquid leakage, and enhancing safety and performance.
Implementation Method 1
carbon particles have a fracture strength of 100 MPa or less
Implementation Method 2
sulfide-based lithium ion-conducting solid electrolyte mainly containing a lithium sulfide and a phosphorus sulfide
Data Source
AI summary
An all-solid-state secondary battery that includes a positive electrode, a negative electrode, and a solid electrolyte, and which has good moldability and favorable battery characteristics. In the all-solid-state secondary battery, a carbon material having carbon particles with a fracture strength of 100 MPa or less is used for an electrode active material.