Anode Mixture for All-Solid-State Battery Conductivity Balance
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Solution Overview
Problem
All-solid-state lithium ion secondary batteries using alloy-based anode active materials face challenges in maintaining capacity retention due to uneven distribution of electroconductive materials caused by excessive ion and electron conductivity, leading to poor cycle characteristics.
Innovation Solution
An anode mixture comprising an alloy-based anode active material, a sulfide-based solid electrolyte, and an electroconductive material, with a specific ratio of electroconductive material volume percentage to BET specific surface area of the solid electrolyte, ensuring balanced ion and electron conductivity paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alloy-based active material is used as anode active material, then theoretical capacity per volume is improved, but capacity retention rate during charge-discharge cycles deteriorates
Solution Approach 1:
The patent controls the volume percentage of electroconductive material within 0.05-5% and solid electrolyte within 5-95%, optimizing the physical parameters of the anode mixture to balance capacity and retention. This parameter optimization resolves the contradiction by finding the optimal composition range that maintains both high capacity and good cycle stability.
Solution Approach 2:
The patent creates a composite anode structure combining alloy-based active material, electroconductive material, and solid electrolyte. This composite approach allows the system to achieve high theoretical capacity from the alloy while the solid electrolyte and electroconductive material work together to maintain structural integrity and conductivity during cycling, improving capacity retention.
2Reliability
If volume percentage of electroconductive material is increased, then electron conductivity is improved, but uniformity of distribution deteriorates
Solution Approach 1:
The patent optimizes the volume percentage of electroconductive material to be within 0.05-5%, preventing excessive aggregation while ensuring sufficient electron conductivity. This controlled parameter range maintains uniform distribution by avoiding both too little (insufficient conductivity) and too much (aggregation and non-uniformity).
Solution Approach 2:
The patent ensures electroconductive material is distributed throughout the anode mixture in a controlled manner, creating local conductive pathways without overwhelming the overall structure. This local quality approach allows electron conductivity to be maintained at necessary points while preserving the uniformity of the overall composition.
3Reliability
If volume percentage of solid electrolyte is increased, then ion conductivity is improved, but density of anode mixture deteriorates
Solution Approach 1:
The patent controls the volume percentage of solid electrolyte within 5-95%, optimizing the balance between ion conductivity and anode mixture density. This parameter optimization ensures sufficient ion transport pathways are created while maintaining a compact, dense structure that maximizes the energy density of the battery.
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 anode mixture maintains high capacity retention rates by preventing uneven distribution of electroconductive materials, ensuring balanced conductivity paths and improved cycle characteristics in all-solid-state lithium ion secondary batteries.
Implementation Method 1
a solid electrolyte... ensuring balanced ion and electron conductivity paths
Implementation Method 2
an electroconductive material... ensuring balanced ion and electron conductivity paths
Implementation Method 3
an alloy-based active material having an average particle diameter of 10 μm or less... a metal such as Si, the metal being able to form an alloy with Li
Data Source
AI summary
Provided are an anode mixture configured to provide excellent cycle characteristics when used in an all-solid-state lithium ion secondary battery, an anode containing the anode mixture, and an all-solid-state lithium ion secondary battery containing the anode. Disclosed is 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; wherein the anode active material contains at least one active material selected from the group consisting of a metal that is able to form an alloy with Li and an oxide of the metal; and wherein a value obtained by dividing, by a BET specific surface area (m2/g) of the solid electrolyte, a volume percentage (%) of the electroconductive material when a volume of the anode mixture is determined as 100 volume %, is 0.09 or more and 1.61 or less.