Solid-State Battery Stack Packaging for Expansion Without Edge Pressure
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Solution Overview
Problem
Solid-state lithium batteries expand and contract during charge and discharge cycles, posing a challenge for packaging that must accommodate these changes without affecting battery performance.
Innovation Solution
The use of an electrochemical stack assembly that includes a frame surrounding the electrochemical stack, with a laminated pouch that contacts only the major surfaces of the stack, allowing for vertical pressure application and preventing pressure on the minor surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the battery is packaged in a rigid container, then the battery is protected from external damage, but the battery cannot expand and contract during charge and discharge cycles
Solution Approach 1:
The packaging is divided into a rigid frame structure that provides overall protection and a flexible pouch that directly contacts the battery. The frame is segmented into walls that create compartments, allowing the flexible pouch to expand and contract within these defined spaces without compromising the structural protection.
Solution Approach 2:
Different parts of the packaging have different mechanical properties: the frame walls provide rigid structural support and protection, while the flexible pouch provides local compliance and accommodation for battery volume changes. This local differentiation of material properties resolves the contradiction between rigid protection and flexible accommodation.
2Reliability
If pressure is applied to the battery during packaging, then the battery maintains good contact with electrodes, but the solid-state electrolyte may crack
Solution Approach 1:
Pressure is applied locally only to the major surfaces of the battery through the flexible pouch, while the minor surfaces are protected by the frame structure. This localized pressure application ensures good electrode contact where needed without subjecting the vulnerable solid-state electrolyte to excessive or uneven stress that would cause cracking.
Solution Approach 2:
The flexible pouch acts as a cushioning element that distributes pressure evenly across the battery surfaces before external forces are applied. This pre-distribution of pressure prevents concentration of stress at specific points that could lead to electrolyte cracking while still maintaining adequate contact between electrodes.
3Adaptability or versatility
If the packaging is made flexible to accommodate expansion, then the battery can charge and discharge freely, but the packaging loses structural protection
Solution Approach 1:
The packaging system is segmented into two functional components: a rigid frame structure that provides structural protection and a flexible pouch that provides accommodation for expansion. This segmentation allows each component to perform its specialized function without compromise.
Solution Approach 2:
The flexible pouch containing the battery is nested within the rigid frame structure. This nested configuration allows the inner flexible component to move and expand freely while being contained and protected by the outer rigid structure, combining both flexibility and structural protection.
Data Source
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AI summary
An electrochemical stack assembly includes a laminated pouch surrounding a frame which encloses solid-state electrochemical cells and electrochemical stacks. In some embodiments, an electrochemical stack assembly includes one or more electrochemical cells, each electrochemical cell comprising a solid-state electrolyte to form at least one electrochemical stack with two major surfaces and four minor surfaces; a frame surrounding the at least one electrochemical stack with space between the frame and each of the four minor surfaces; and a laminated pouch surrounding the frame and the at least one electrochemical stack, the laminated pouch in contact with one or both of the major surfaces. In some embodiments, the frame comprises a tray. In some embodiments, the electrochemical stack assembly comprises two trays, each with an electrochemical stack comprising an electrochemical cell, the cell comprising a solid-state electrolyte.