Asymmetric Secondary Battery Electrode Assembly Design
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Solution Overview
Problem
Secondary batteries face safety risks due to the potential for short circuits between the positive and negative electrode sheets during charging, which can lead to lithium precipitation and puncture of the separator, causing safety accidents.
Innovation Solution
The electrode assembly design includes a positive electrode sheet, a separator, and a negative electrode sheet, where the edges of the separator extend beyond the edges of the negative pole main body area, and the negative pole active material layer is wider than the positive pole active material layer, ensuring complete insulation and preventing lithium precipitation, with additional insulating layers on the positive pole tab areas to prevent burrs from piercing the separator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the separator width is reduced to match the positive electrode sheet width, then material cost is reduced, but short circuit risk increases due to insufficient insulation between electrode edges
Solution Approach 1:
The patent applies asymmetry by making the negative electrode sheet wider than the positive electrode sheet, creating an asymmetric structure where the negative electrode extends beyond the positive electrode edges. This asymmetric design ensures that the separator, which matches the positive electrode width, provides sufficient insulation coverage while the extended negative electrode areas are naturally protected, thus preventing short circuits without requiring excessive separator material.
2Device complexity
If the negative electrode sheet width is reduced to match the positive electrode sheet width, then manufacturing complexity is reduced, but lithium precipitation risk increases during charging
Solution Approach 1:
The patent employs asymmetry by designing the negative electrode sheet to be wider than the positive electrode sheet. This asymmetric configuration ensures that during charging, lithium ions can be smoothly embedded into the negative electrode without precipitation, as the extended negative electrode areas provide adequate accommodation space. The asymmetric design is simple to manufacture while effectively preventing lithium precipitation.
3Reliability
If insulating layers are added to the positive pole tab areas, then short circuit prevention is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by adding insulating layers specifically to the positive pole tab areas where burrs are most likely to form and cause short circuits. This localized approach provides enhanced protection precisely where needed, rather than uniformly insulating the entire positive electrode sheet. The selective application of insulating material optimizes safety while minimizing manufacturing complexity and material usage.
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 design effectively prevents short circuits and lithium precipitation, enhancing the safety and reliability of the battery while reducing production costs by optimizing the use of materials and avoiding waste.
Implementation Method 1
the separator is sandwiched between the positive pole active material layer and the negative pole active material layer... the positive pole active material layer and the negative pole active material layer can be completely insulated from each other
Implementation Method 2
the lithium ions detached from the positive pole active material layer can be smoothly embedded into the negative pole active material layer, thereby avoiding the occurrence of lithium precipitation
Data Source
AI summary
An electrode assembly of a secondary battery and a secondary battery are provided. The assembly has a positive electrode sheet, a separator and a negative electrode sheet. The positive electrode sheet has a positive electrode main body area and a positive pole tab area. A side of the positive electrode main body area is coated with a positive pole active material layer. The negative electrode sheet has a negative pole main body area and a negative pole tab area. A side of the negative pole main body area is coated with a negative pole active material layer. The separator is sandwiched between the positive pole active material layer and the negative pole active material layer.