Constrained Electrode Assembly for Battery Expansion Control
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Solution Overview
Problem
Rocking chair secondary batteries face challenges with electrode expansion and contraction during cycling, leading to reliability and cycle life issues, as well as electrode alignment mismatches causing electrical shorts and failures.
Innovation Solution
The implementation of constraint structures within the battery to mitigate electrode expansion and improve mechanical stability, including a primary and secondary growth constraint system that restricts the electrode assembly's growth, maintaining alignment and preventing excessive footprint increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrodes are allowed to expand and contract freely during battery cycling, then the battery can maintain its structural flexibility and accommodate volume changes, but electrical shorts and battery failures occur due to electrode expansion and contraction
Solution Approach 1:
The patent applies preliminary anti-action by introducing constraint structures (such as rigid backings, adhesives, or housing features) that pre-establish opposing forces to counteract the expansion and contraction of electrodes during cycling. These constraints are built into the battery structure before operation, preventing the harmful dimensional changes that would otherwise lead to electrical shorts and failures.
2Reliability
If constraint structures are added to control electrode expansion, then reliability and cycle life are improved, but the device complexity increases
Solution Approach 1:
The patent merges the constraint function with existing battery components rather than adding entirely separate constraint structures. For example, rigid backings are integrated with the housing, adhesives are applied at existing attachment points, and housing features serve dual purposes as both structural elements and constraint mechanisms. This combining approach improves reliability while minimizing the increase in device complexity.
3Reliability
If electrode alignment is controlled to prevent shorts, then battery reliability improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-positioning electrodes and constraint structures during assembly to ensure proper alignment before the battery undergoes cycling or experiences mechanical stresses. Features such as pre-applied adhesives, pre-formed rigid backings, and pre-designed housing features establish the correct electrode positions in advance, preventing misalignment and shorts without requiring extremely high manufacturing precision during final assembly.
Data Source
AI summary
A secondary battery for cycling between a charged and a discharged state, wherein a 2D map of the median vertical position of the first opposing vertical end surface of the electrode active material in the X-Z plane, along the length LE of the electrode active material layer, traces a first vertical end surface plot, EVP1, a 2D map of the median vertical position of the first opposing vertical end surface of the counter-electrode active material layer in the X-Z plane, along the length LC of the counter-electrode active material layer, traces a first vertical end surface plot, CEVP1, wherein for at least 60% of the length LC of the first counter-electrode active material layer (i) the absolute value of a separation distance, SZ1, between the plots EVP1 and CEVP1 measured in the vertical direction is 1000 μm≥|SZ1|≥5 μm.