Electrode Precursor Sheet Binder Tuning for Dense Solid-State Batteries
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Solution Overview
Problem
All-solid state secondary batteries face issues with increased resistance and defects in the active material layer due to disintegration of solid particles during transport and roll winding in industrial manufacturing methods, leading to poor transportability and battery performance.
Innovation Solution
A sheet for an electrode with an active material layer precursor containing an inorganic solid electrolyte and a polymer binder, where the binder content is 3% by mass or less and the filling rate is 35% to 50%, allowing for high transportability and conversion into a high-filling-rate active material layer with low resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a relatively large amount of binder is used to firmly bind solid particles in a dense state, then the filling rate of the active material layer is improved, but the resistance increases due to electron-insulating and ion-insulating properties of the binder
Solution Approach 1:
The invention changes the key parameter of binder content from conventional high amounts (5% by mass or more) to a specific low range (0.1 wt% to 5 wt%, preferably 0.5 wt% to 3 wt%). This parameter change resolves the contradiction by achieving sufficient particle binding and dense packing through optimized binder dosage, thereby maintaining high filling rate while minimizing the resistive effect of the binder material.
2Reliability
If solid particles are bound at a high filling rate to form an active material layer, then the battery performance is improved, but the transportability deteriorates due to disintegration of solid particles during transport and roll winding
Solution Approach 1:
The invention applies preliminary action by forming the active material layer at a controlled, moderate filling rate during manufacturing, rather than attempting to achieve high filling rate after the layer is formed. This preliminary structuring of the layer with appropriate binder content ensures particle stability during transport, and subsequent pressing during battery manufacturing achieves the desired high filling rate for optimal performance without causing particle disintegration.
3Manufacturing precision
If the active material layer is pressed to increase density and filling rate, then the battery performance is improved, but defects occur due to disintegration of solid particles during pressing
Solution Approach 1:
The invention applies beforehand cushioning by incorporating an optimized amount of binder (0.1 wt% to 5 wt%) into the active material layer formulation before pressing. This binder acts as a cushioning agent that binds solid particles together in advance, preventing particle disintegration during the subsequent pressing operation. The preliminary binding protection enables successful pressing to achieve high filling rate and density without generating defects from particle breakdown.
Data Source
AI summary
There are provided a sheet for an electrode, which includes an active material layer precursor layer containing an inorganic solid electrolyte, an active material, and a polymer binder, in which the active material layer precursor layer is such that a content of the polymer binder is 3% by mass or less and a filling rate of 35% to 50% is exhibited, a manufacturing method therefor, an all-solid state secondary battery, and manufacturing methods for an electrode sheet and an all-solid state secondary battery, in which this sheet for an electrode is used.