Solid-Electrolyte Battery Bonding via Thermal Crystallization
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Solution Overview
Problem
Nonaqueous-electrolyte batteries face issues with cracking of powder-molded active-material layers during high-pressure bonding, leading to performance degradation and the formation of high-resistance bonding interfaces, which reduces discharge capacity and output.
Innovation Solution
A method involving the production of nonaqueous-electrolyte batteries with amorphous sulfide-solid-electrolyte layers formed by a vapor-phase process, followed by heat treatment to crystallize these layers, eliminating the need for high-pressure compression and minimizing the formation of high-resistance interfaces between electrode bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high pressure is applied to bond electrode bodies together, then bonding strength is improved, but the active-material layers are cracked and performance degrades
Solution Approach 1:
The patent changes the bonding method from mechanical press-bonding to thermal bonding. The solid-electrolyte layers are heated to a temperature where they become soft and adhesive, enabling bonding without high pressure. This parameter change (from pressure-driven to temperature-driven bonding) resolves the contradiction by eliminating the cracking issue while maintaining bonding strength.
Solution Approach 2:
The patent replaces the mechanical bonding system (press-bonding) with a thermal bonding system. Instead of using mechanical pressure to bond the electrode bodies, the invention uses heat to activate the adhesive properties of the solid-electrolyte layers, substituting a mechanical process with a thermal process that avoids the harmful effects of high pressure.
2Strength
If solid-electrolyte layers are press-bonded together, then bonding is achieved, but a high-resistance bonding interface is formed reducing discharge capacity
Solution Approach 1:
The patent changes the bonding parameter from pressure to temperature. By heating the solid-electrolyte layers to their softening point, the material becomes more compliant and forms a continuous, low-resistance bonding interface. This thermal parameter change eliminates the high-resistance interface problem that occurs with cold press-bonding.
Solution Approach 2:
The patent utilizes the phase transition of the solid-electrolyte layers from a hard, brittle state to a soft, adhesive state through heating. This phase change enables the material to flow and form intimate contact with the electrode bodies, creating a low-resistance interface that maintains high discharge capacity while achieving proper bonding.
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 approach prevents cracking in the electrode layers and reduces resistance at the bonding interface, resulting in improved discharge capacity and output while maintaining a smaller battery thickness.
Implementation Method 1
a heat treatment under application of a pressure to crystallize the PSE layer and the NSE layer
Implementation Method 2
a positive-electrode-side solid-electrolyte layer that is amorphous and formed on the positive-electrode active-material layer by a vapor-phase process
Data Source
AI summary
A positive-electrode body 1 is prepared that includes a positive-electrode active-material layer 12 including a powder-molded body, and a positive-electrode-side solid-electrolyte layer (PSE layer) 13 that is amorphous and formed on the positive-electrode active-material layer 12 by a vapor-phase process. A negative-electrode body 2 is prepared that includes a negative-electrode active-material layer 22 including a powder-molded body, and a negative-electrode-side solid-electrolyte layer (NSE layer) 23 that is amorphous and formed on the negative-electrode active-material layer 22 by a vapor-phase process. The positive-electrode body 1 and the negative-electrode body 2 are bonded together by subjecting the electrode bodies 1 and 2 being arranged such that the solid-electrolyte layers 13 and 23 of the electrode bodies 1 and 2 are in contact with each other, to a heat treatment under application of a pressure to crystallize the PSE layer 13 and the NSE layer 23.