Secondary Battery Cavities Absorb Anode Expansion Stress
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining capacity and lifespan due to internal stress caused by volume changes during charging and discharging, which can lead to anode expansion and pressure on adjacent components, potentially resulting in cracks and separation of anode and electrolyte membrane.
Innovation Solution
The design incorporates a secondary battery with a support member between unit cells, featuring cavities that accommodate volume changes of the anode and cathode, and an elastically deformable support member with ion conductivity to absorb stress, preventing collapse and maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the anode volume is allowed to expand during charging, then the battery capacity is improved, but internal stress increases causing structural damage
Solution Approach 1:
The battery is divided into multiple unit cells with cavities between them, allowing each cell to expand independently into its own cavity space, preventing stress concentration and structural damage while maintaining high capacity
Solution Approach 2:
Cavities are pre-designed between unit cells to accommodate future volume expansion of the anode during charging, acting as a cushion that absorbs expansion stress before it can cause structural damage to the battery components
2Strength
If the support member is rigid to maintain structural stability, then mechanical strength is improved, but stress absorption during volume change is reduced
Solution Approach 1:
The support member's mechanical properties are optimized by selecting materials with appropriate elastic moduli (0.1-10 GPa), creating a balance between rigidity for structural support and elasticity for stress absorption during anode volume changes
Solution Approach 2:
The support member is made from composite materials or materials with specific elastic properties that combine structural stability with the ability to deform elastically, allowing it to maintain support function while absorbing expansion stress
3Duration of action of stationary object
If cavities are added between unit cells to accommodate expansion, then lifespan is improved, but device complexity increases
Solution Approach 1:
The battery structure is segmented into discrete unit cells with standardized cavity spaces between them, making the design modular and manufacturable despite the added complexity of stress accommodation features
Solution Approach 2:
The cavities serve multiple functions: they accommodate anode expansion, provide structural spacing between cells, and facilitate stress distribution, reducing the need for additional separate components and minimizing overall structural complexity
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 configuration effectively absorbs stress and prevents structural damage, enhancing the battery's capacity and lifespan by allowing for volume expansion without causing cracks or separation between anode and electrolyte membrane.
Implementation Method 1
a support member configured to support the plurality of unit cells in the left to right direction is disposed between unit cells of the plurality of unit cells... The support member may be elastically deformable
Implementation Method 2
an electrolyte membrane surrounding at least three surfaces of the cathode... The support member may have ion conductivity
Data Source
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AI summary
A secondary battery including: a plurality of unit cells, wherein each unit cell of the plurality of unit cells includes a cathode extending in a top to bottom direction, an electrolyte membrane surrounding at least three surfaces of the cathode, and an anode surrounding at least a portion of the electrolyte membrane, wherein unit cells of the plurality of unit cells are spaced apart from each other in a left to right direction, with cavities therebetween, and a support member configured to support the plurality of unit cells in the left to right direction and disposed between unit cells of the plurality of unit cells.