Anode Mixture for All-Solid-State Battery
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Solution Overview
Problem
All-solid-state lithium ion secondary batteries using alloy-based anode active materials suffer from low capacity retention rates due to uneven distribution of electroconductive materials, leading to blocked electron conducting paths and volume changes during charge-discharge cycles.
Innovation Solution
An anode mixture comprising an alloy-based anode active material, a LiX—Li2S—P2S5-based solid electrolyte, and an electroconductive material, where the volume percentage of the electroconductive material is optimized by multiplying with the bulk density of the solid electrolyte to maintain a specific range, ensuring balanced ion and electron conducting paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alloy-based anode active material is used to increase theoretical capacity, then capacity per volume is improved, but capacity retention rate deteriorates due to volume changes during charge-discharge cycles
Solution Approach 1:
The patent changes the physical and chemical parameters of the anode mixture by controlling the volume percentage of electroconductive material and using specific solid electrolyte bulk density values. This creates a optimized microstructure that accommodates volume changes during Li alloying/dealloying cycles, maintaining capacity retention while preserving high theoretical capacity of alloy-based materials.
Solution Approach 2:
The patent creates a composite anode mixture comprising alloy-based anode active material, solid electrolyte, and electroconductive material in specific proportions. This composite structure provides both high capacity (from alloy material) and good cycle stability (from the composite matrix that accommodates volume expansion/contraction).
2Reliability
If electroconductive material is added to improve electron conduction, then electrical conductivity is improved, but uneven distribution occurs leading to blocked electron conducting paths
Solution Approach 1:
The patent specifies precise parameter ranges: volume percentage of electroconductive material multiplied by bulk density of solid electrolyte should be 0.53-3.0. This parameter control ensures uniform distribution of electroconductive material throughout the anode mixture, preventing aggregation and blocked conduction paths while maintaining excellent electron conductivity.
3Reliability
If solid electrolyte bulk density is increased to improve ion conduction, then ion conductivity is improved, but electroconductive material distribution becomes uneven
Solution Approach 1:
The patent uses the bulk density of solid electrolyte as a key control parameter in the relationship: volume percentage of electroconductive material × bulk density of solid electrolyte = 0.53-3.0. By controlling this product within the specified range, the patent achieves both good ion conductivity (from solid electrolyte) and uniform electroconductive material distribution, resolving the contradiction between these two requirements.
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 optimized anode mixture prevents uneven distribution of electroconductive materials, maintaining high capacity retention rates and improving cycle characteristics in all-solid-state lithium ion secondary batteries.
Implementation Method 1
an active material (an alloy-based active material) containing a metal such as Si, the metal being able to form an alloy with Li
Implementation Method 2
the solid electrolyte is a LiX—Li2S—P2S5-based solid electrolyte
Implementation Method 3
an electroconductive material... ensuring balanced ion and electron conducting paths
Data Source
AI summary
Disclosed is an anode mixture configured to provide an all-solid-state lithium ion secondary battery being excellent in cycle characteristics when it is used in the battery, an anode including the anode mixture, and an all-solid-state lithium ion secondary battery including the anode. The anode mixture may be an anode mixture for an all-solid-state lithium ion secondary battery, wherein the anode mixture contains an anode active material, a solid electrolyte and an electroconductive material; and wherein a value obtained by multiplying, by a bulk density of the solid electrolyte, a volume percentage (%) of the electroconductive material when a volume of the anode mixture is determined as 100 volume %, is 0.53 or more and 3.0 or less.