Corrugated Battery Case for Cell Stack Swelling Control
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Solution Overview
Problem
Lithium batteries with liquid electrolytes face high risks of overheating and fire due to flammable organic solvents, and they experience decreased energy density and cycle characteristics due to volume changes during charge and discharge.
Innovation Solution
A lithium battery with a new structure featuring a unit cell stack and a battery case with a corrugated portion in the side, which alleviates volume changes and applies constant pressure, thereby suppressing interfacial resistance and maintaining energy density and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate elastic member is disposed between the unit cell stack and the battery case to alleviate volume changes and apply constant pressure, then cycle characteristics are improved, but energy density decreases
Solution Approach 1:
The invention merges the elastic member function with the battery case structure by forming the corrugated portion directly on the inner surface of the battery case. This integration eliminates the need for a separate elastic member while maintaining the volume change accommodation and constant pressure application functions, thereby preserving cycle characteristics without sacrificing energy density.
Solution Approach 2:
The battery case is designed to perform multiple functions: it provides structural containment, accommodates volume changes through the corrugated portion, and applies constant pressure to the unit cell stack. The corrugated portion serves as both a structural feature of the case and an elastic element, demonstrating multi-functionality that resolves the contradiction between reliability improvement and energy density maintenance.
2Quantity of substance
If no separate elastic member is included in the battery case to maintain energy density, then energy density is improved, but cycle characteristics deteriorate due to increased interfacial resistance from volume changes
Solution Approach 1:
The invention merges the elastic member function with the battery case structure by forming the corrugated portion directly on the inner surface of the battery case. This integration eliminates the need for a separate elastic member while maintaining the volume change accommodation and constant pressure application functions, thereby preserving cycle characteristics without sacrificing energy density.
Solution Approach 2:
The corrugated portion on the battery case inner surface acts as a flexible structure that can deform to accommodate volume changes of the unit cell stack during charging and discharging. This flexible design maintains contact pressure without requiring additional elastic components, thus improving cycle characteristics while maintaining energy density.
3Use of energy by moving object
If the unit cell stack volume changes during charge and discharge, then electrochemical function is achieved, but interfacial resistance increases causing cycle characteristic deterioration
Solution Approach 1:
The corrugated portion on the battery case inner surface acts as a flexible structure that can deform to accommodate volume changes of the unit cell stack during charging and discharging. This flexible design maintains contact pressure without requiring additional elastic components, thus improving cycle characteristics while maintaining energy density.
Solution Approach 2:
The corrugated portion provides dynamic adaptation to the unit cell stack's volume changes during electrochemical operation. The structure can expand and contract with the stack while maintaining constant pressure contact, preventing interfacial resistance increase and preserving cycle characteristics throughout the battery's operational life.
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 new structure effectively suppresses the decrease in energy density and cycle characteristics, improves heat dissipation, and enhances thermal stability and high-temperature stability of the lithium battery.
Implementation Method 1
an elastic member may be disposed between the unit cell stack and the battery case to alleviate volume changes during charge and discharge of the unit cell stack and to apply a constant pressure to the unit cell stack
Implementation Method 2
Compared to liquid electrolytes, solid electrolytes may be less likely to overheat and be set on fire in the event of a short circuit
Data Source
AI summary
A lithium battery including a unit cell stack including a plurality of unit cells stacked in a thickness direction thereof; and a battery case for accommodating the unit cell stack, wherein the battery case includes an upper surface portion adjacent to an upper end surface of the unit cell stack, a lower surface portion adjacent to a lower end surface of the unit cell stack, and a side portion connecting the upper surface portion and the lower surface portion, and the side portion includes a corrugated portion disposed in the thickness direction of the unit cell stack.