Battery Cell Assembly Layout for Middle-Cell Expansion Stress
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Solution Overview
Problem
Lithium-ion batteries experience stress concentration and capacity plunge due to volume expansion in the middle cells during cycling, leading to lithium precipitation.
Innovation Solution
Incorporating a first elastic buffer pad in the middle battery cells and symmetrically arranging second battery cells on both sides, with controlled compression rates and porosities, to absorb volume expansion and reduce stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If elastic buffer pads are added to middle battery cells to absorb volume expansion, then volume stability is improved, but energy density decreases due to occupied space
Solution Approach 1:
The patent applies elastic buffer pads selectively only to middle battery cells (first battery cell assembly) rather than all cells, based on the local need to address stress concentration in the middle region while preserving energy density in side cells (second battery cell assembly)
Solution Approach 2:
The patent optimizes the compression rate of the elastic buffer pad within 5-50%, and controls its thickness to be 1-20mm, balancing the expansion absorption capability with minimal impact on energy density
2Reliability
If elastic buffer pads are added to reduce expansion force, then reliability is improved by preventing lithium precipitation, but device complexity increases
Solution Approach 1:
The patent divides the battery into two assemblies: first battery cell assembly (middle cells with elastic buffer pads) and second battery cell assembly (side cells without buffer pads), segmenting the solution to apply complexity only where needed
Solution Approach 2:
The elastic buffer pad acts as an intermediary component between the electrode assembly and the battery cell housing, absorbing expansion forces and protecting the middle cells from stress concentration and lithium precipitation
3Stability of the object's composition
If symmetric arrangement of second battery cells is implemented, then structural stability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses asymmetric design by placing the first battery cell assembly (with elastic buffer pads) in the middle and second battery cell assemblies (without buffer pads) on both sides, creating an asymmetric structure that is symmetric in function, reducing the need for high manufacturing precision while maintaining structural stability
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
Improves volume stability and balances energy density by mitigating stress concentration and lithium precipitation in middle cells, enhancing overall battery performance.
Implementation Method 1
the first battery cell being internally provided with a first elastic buffer pad... conducive to absorbing the volume expansion of the battery cells
Implementation Method 2
the elastic buffer pad has a porous structure... the porous structure of the elastic buffer pad is conducive to absorbing and releasing the electrolyte
Data Source
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Figure 3
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AI summary
The present application discloses a battery and an electric apparatus. The battery includes: a first battery cell assembly, the first battery cell assembly including at least one first battery cell, the first battery cell being internally provided with a first elastic buffer pad; a second battery cell assembly, the second battery cell assembly including at least two second battery cells, the at least two second battery cells being disposed on both sides of the first battery cell assembly along a thickness direction of the first battery cell assembly, where the thickness direction of the first battery cell assembly is consistent with a thickness direction of the first battery cell.