All-Solid-State Battery Electrode Pressing to Prevent End Cracking
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Solution Overview
Problem
Roll-pressing of negative electrode active material layers containing lithium-titanium oxide in all-solid-state battery production often results in cracking at the ends of the electrodes, which is not effectively addressed by existing methods.
Innovation Solution
Incorporating a stress relaxation rate of 32.5% or more in the negative electrode active material layer before roll-pressing, and including VGCF only at the ends of the layer perpendicular to the lamination direction to enhance adhesiveness and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If roll-pressing is used to consolidate the negative electrode active material layer, then productivity and consolidation efficiency are improved, but cracking occurs at the ends of the electrode
Solution Approach 1:
The patent applies preliminary action by performing a first pressing operation at a lower pressure (0.1 to 10 MPa) before the main roll-pressing consolidation step. This preliminary pressing pre-compresses the negative electrode active material layer, reducing internal stresses and preventing cracking during subsequent high-pressure roll-pressing, thus maintaining both productivity and reliability
2Strength
If the negative electrode active material layer is consolidated by roll-pressing, then the consolidation strength is improved, but end cracking occurs due to stress concentration
Solution Approach 1:
The patent applies local quality by implementing a two-stage pressing process with different pressure levels: a first pressing step with lower pressure (0.1 to 10 MPa) applied uniformly, followed by a second roll-pressing step with higher pressure for consolidation. This localized pressure differentiation ensures end regions are pre-compressed to prevent cracking while the center receives full consolidation pressure
Solution Approach 2:
The first pressing operation serves as beforehand cushioning by applying a moderate compressive stress that pre-densifies the negative electrode active material layer, particularly at the ends where stress concentration occurs during roll-pressing. This cushioning effect absorbs potential cracking stresses before the main consolidation step
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 effectively suppresses cracking at the electrode ends during roll-pressing and reduces battery resistance by ensuring adequate adhesiveness and stress relaxation, improving the production process and performance of all-solid-state batteries.
Implementation Method 1
a stress relaxation rate of the negative electrode active material layer prior to the roll-pressing is 32.5% or more
Data Source
AI summary
To provide a method for production of an all-solid-state battery in which cracking of the ends of the electrodes can be suppressed even if a negative electrode active material layer including lithium-titanium oxide is roll-pressed, provided is a method for the production of an all-solid-state battery, including roll-pressing to consolidate a negative electrode active material layer; wherein the all-solid-state battery has a structure including a laminate of a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, the negative electrode active material layer, and a negative electrode current collector layer in this order, the negative electrode active material layer includes a lithium-titanium oxide as a negative electrode active material, and prior to the roll-pressing, a stress relaxation rate of the negative electrode active material layer is 32.5% or more.