Solid-State Electrode Assembly for Pouch Battery Pressure Control
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Solution Overview
Problem
The lifetime of pouch-type secondary batteries is adversely affected by changes in internal pressure due to volume changes during charging and discharging, necessitating a solution to effectively control internal pressure.
Innovation Solution
An electrode assembly with a polymer layer having a yield strength of 5 MPa to 20 MPa and specific thickness, combined with a solid electrolyte layer, is used to manage internal pressure fluctuations, comprising a sulfide-based solid electrolyte and polymer layers on both ends of the assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pouch-type secondary battery is designed with conventional electrode assembly structure, then the battery can be manufactured with standard processes, but the internal pressure changes during charging and discharging adversely affect the battery lifetime
Solution Approach 1:
A buffer layer is introduced as an intermediary component between the electrode assembly and the sealing plate. This buffer layer absorbs and mitigates the internal pressure changes that occur during charging and discharging cycles, preventing direct transmission of stress to the sealing plate and electrode assembly, thereby extending battery lifetime while maintaining standard manufacturing processes
Solution Approach 2:
The buffer layer is designed with specific material parameters (yield strength of 5-20 MPa and controlled thickness) that enable it to deform elastically under pressure. By carefully selecting these parameters, the buffer layer can accommodate volume expansion during charging without compromising the structural integrity of the battery, thus resolving the pressure-lifetime contradiction
2Stress or pressure
If the polymer layer thickness is increased to control internal pressure, then the pressure control capability is improved, but the battery volume increases
Solution Approach 1:
By optimizing the thickness parameter of the polymer buffer layer and controlling its yield strength within 5-20 MPa, the design achieves effective pressure control with minimal volume increase. The buffer layer thickness is carefully calculated to provide sufficient compliance during charging while maintaining a compact overall battery form factor
Solution Approach 2:
The buffer layer is constructed from polymer materials with specific mechanical properties that provide optimal balance between pressure absorption capability and volume efficiency. The composite structure of the buffer layer, sealing plate, and electrode assembly creates a synergistic system where each component contributes to both pressure control and space efficiency
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 electrode assembly effectively controls internal pressure changes, enhancing the lifetime properties of the secondary battery by maintaining constant pressure and structural stability during operation.
Implementation Method 1
polymer layers on both ends of the electrode assembly... yield strength of 5 MPa to 20 MPa... effectively controls internal pressure changes
Data Source
AI summary
An electrode assembly and a secondary battery comprising the same are provided. The electrode assembly includes a plurality of electrode structures, each of which comprising a positive electrode, a negative electrode, and a solid electrolyte layer between the positive electrode and the negative electrode, and polymer layers at both ends of the electrode assembly.