Bipolar Solid-State Cell Stack With Compression Pad for Volume Change
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Solution Overview
Problem
Conventional all-solid secondary batteries face challenges in designing a structure capable of absorbing volume changes due to lithium deposition reactions, and the use of expensive current collectors like SUS increases costs.
Innovation Solution
A bipolar stack unit cell structure with a compression pad made of elastic material, such as polyurethane, is introduced between anode current collectors to absorb volume changes, allowing for stable lifetime and simultaneous provision of stack and bipolar structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a bipolar structure is used in all-solid secondary batteries, then the number of parts is reduced and high power and high energy density are achieved, but the structure cannot absorb volume changes due to lithium deposition reactions
Solution Approach 1:
A compression pad made of elastic material is introduced between the anode current collectors of adjacent bicells. This elastic compression pad acts as a flexible buffer that can absorb the volume expansion caused by lithium deposition reactions while maintaining the bipolar structure's high power and energy density advantages.
Solution Approach 2:
The compression pad serves as an intermediary element between the rigid bipolar structure and the expanding anode. It mediates the volume change by providing a compliant interface that absorbs expansion forces, preventing structural damage while maintaining electrical connectivity.
2Strength
If expensive current collectors like SUS are used, then structural integrity is maintained, but manufacturing cost increases
Solution Approach 1:
The compression pad is made of inexpensive elastic materials such as polyurethane or natural rubber instead of expensive SUS current collectors. This substitution significantly reduces manufacturing costs while the pad's elastic properties provide sufficient structural support and volume change absorption.
Solution Approach 2:
The invention changes the material parameter from expensive metal (SUS) to inexpensive elastic polymer materials. This parameter change maintains functional integrity through the elastic properties of the compression pad, achieving both cost reduction and structural adequacy.
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 structure effectively suppresses volume changes, enabling stable battery performance and capacity design, while reducing the need for expensive current collectors.
Implementation Method 1
a compression pad is provided between the first anode current collector and second anode current of adjacent bicells of the plurality of bicells
Data Source
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AI summary
Disclosed are a bipolar stack unit cell structure (1) and an all-solid secondary battery (2) including the same. The bipolar stack unit cell structure includes: a bicell (100) in which a first anode current collector (10), a first anode active material layer (20), a first electrolyte layer (30), a first cathode active material layer (40), a cathode current collector (50), a second cathode active material layer (40'), a second electrolyte layer (30'), a second anode active material layer (20'), and a second anode current collector (10') are sequentially arranged, wherein a plurality of the bicells (100) are stacked, and a compression pad (60) is provided between the first anode current collector (10) and second anode current collector (10') of adjacent bicells (100) of the plurality of bicells (100). The bipolar stack unit cell structure (1) absorbs a volume change of an anode and suppresses a volume change of the entire cell to obtain a stable lifespan, and the capacity and voltage thereof can be freely designed by bipolar connection of the unit cells.