All-Solid-State Battery Pressing to Prevent Electrolyte Penetration
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Solution Overview
Problem
The presence of secondary particles of active material in the active material layers of all solid-state batteries can cause short circuits between the cathode and anode due to their penetration through the solid electrolyte layer during the pressing process.
Innovation Solution
A method involving the crushing of secondary particles to primary particles at the interface between the active material and solid electrolyte layers, with a diameter ratio of primary particles to electrolyte layer thickness maintained at 0<(X/Y)≤0.1, to prevent particle penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If secondary particles of active material are contained in the active material layer, then the interfacial resistance is reduced and discharge capacity is improved, but short circuits occur between cathode and anode due to particle penetration through the solid electrolyte layer
Solution Approach 1:
The invention applies preliminary action by crushing secondary particles into primary particles before the pressing step. The active material layers are prepared containing secondary particles to improve interfacial resistance, but before final assembly pressing, these secondary particles are mechanically crushed into smaller primary particles. This preliminary size reduction prevents the particles from penetrating through the solid electrolyte layer during subsequent pressing operations, thereby eliminating the short circuit risk while maintaining the beneficial interfacial contact properties
Solution Approach 2:
The invention applies parameter changes by modifying the particle size parameter of the active material. Secondary particles with larger diameter are transformed into primary particles with smaller diameter (specifically, particles with diameter less than 1/10 of the solid electrolyte layer thickness). This parameter change from secondary to primary particle size maintains good interfacial contact for reducing resistance while preventing penetration through the electrolyte layer during pressing
2Reliability
If the stack is pressed to unify solid particles and reduce interfacial resistance, then the discharge capacity improves, but secondary particles may enter and penetrate the solid electrolyte layer causing short circuits
Solution Approach 1:
The crushing step is performed as a preliminary action before the pressing step. By reducing secondary particles to primary particles beforehand, the subsequent pressing operation can proceed with higher pressure to achieve better particle unification and lower interfacial resistance without the risk of particle penetration, since the particles are now too small to penetrate the solid electrolyte layer
Solution Approach 2:
The invention changes the particle size parameter from secondary particle diameter to primary particle diameter (less than 1/10 of electrolyte thickness). This parameter change enables the pressing process to effectively unify particles and reduce interfacial resistance while the reduced particle size inherently prevents penetration through the solid electrolyte layer
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 method effectively suppresses short circuits by ensuring that only primary particles, which are smaller than the electrolyte layer thickness, enter the electrolyte, thereby preventing cathode-anode contact.
Implementation Method 1
a second step of pressing the stack to constitute a compact, wherein in the first step, the active material layer contains a secondary particle of an active material, and in the second step, the secondary particle is crushed to primary particles by said pressing
Data Source
AI summary
It is suppressed that an active material particle enters into or penetrates through a solid electrolyte layer when an active material layer and the solid electrolyte layer are pressed and that short circuits between a cathode and an anode occur. A method for producing an all solid-state battery includes: a first step of stacking an active material layer over at least one surface of a solid electrolyte layer to constitute a stack; and a second step of pressing the stack to constitute a compact, wherein in the first step, the active material layer contains a secondary particle of an active material, and in the second step, the secondary particle is crushed to primary particles by said pressing, the secondary particle being present in an interfacial portion between the active material layer and the solid electrolyte layer.