All-solid-state battery anode mixture voidage control
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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 aggregation of electroconductive materials and subsequent blocking of electron conducting paths, especially during initial charge-discharge cycles.
Innovation Solution
A method for producing all-solid-state lithium ion secondary batteries with an anode mixture that includes a metal capable of forming alloys with Li, an oxide of the metal, and an electroconductive material, where the voidage of the dried anode mixture is maintained between 43% and 54%, ensuring even distribution of the electroconductive material and maintaining ion and electron conductivity.
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 increased, but capacity retention rate deteriorates during charge-discharge cycles
Solution Approach 1:
The invention changes the physical parameter of voidage in the anode mixture to a specific range (43-54%) to resolve the contradiction between high capacity and good retention. This parameter change prevents electroconductive material aggregation while maintaining alloy-based active material performance, thereby achieving both high theoretical capacity and excellent capacity retention during cycles
Solution Approach 2:
The invention utilizes a porous anode mixture structure with controlled voidage (43-54%) to prevent aggregation of electroconductive materials. The porous structure maintains adequate spacing between particles, ensuring continuous electron conducting paths and ion conducting paths, which resolves the capacity retention issue while preserving the high capacity benefits of alloy-based materials
2Reliability
If anode mixture voidage is increased to prevent electroconductive material aggregation, then capacity retention improves, but density decreases
Solution Approach 1:
The invention optimizes the voidage parameter to a specific range (43-54%) that balances two competing requirements: preventing electroconductive material aggregation (which requires higher voidage) and maintaining adequate density (which requires lower voidage). This precise parameter control achieves both capacity retention and reasonable density
3Quantity of substance
If alloy-based active material is used, then electron conducting paths are blocked during initial cycles, but this leads to low capacity retention
Solution Approach 1:
The porous anode mixture structure with voidage of 43-54% maintains adequate spacing between alloy-based active material particles and electroconductive materials. This prevents complete blocking of electron conducting paths during initial charge-discharge cycles, allowing electrons to continuously reach the active material and achieve high capacity retention
Solution Approach 2:
The controlled voidage structure acts as an intermediary space that facilitates the movement of electroconductive materials and maintains conducting paths. This intermediary structure prevents direct contact and aggregation between electroconductive materials and alloy particles, ensuring continuous electron transport during cycling
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 method enhances cycle characteristics and capacity retention rates by preventing uneven distribution of electroconductive materials and maintaining balanced ion and electron conducting paths, even with alloy-based anode active materials.
Implementation Method 1
an anode mixture forming step of obtaining an anode mixture by drying a raw material for an anode mixture
Implementation Method 2
an electricity passing step of passing electricity through a laminate comprising a cathode mixture, the anode mixture and a solid electrolyte material part disposed between the electrode mixtures to change the cathode mixture, the anode mixture and the solid electrolyte material part into a cathode, an anode and a solid electrolyte layer, respectively
Data Source
AI summary
Disclosed is a method for producing an all-solid-state lithium ion secondary battery being excellent in cycle characteristics. The production method may be a method for producing an all-solid-state lithium ion secondary battery, wherein the method comprises an anode mixture forming step of obtaining an anode mixture by drying a raw material for an anode mixture, which contains an anode active material, a solid electrolyte and an electroconductive material; and wherein, for the anode mixture after being dried in the anode mixture forming step, a voidage V of the inside of the anode mixture calculated by the following formula (1) is 43% or more and 54% or less:V=100−(D1/D0)×100 Formula (1).