Pouch Cell Electrode Bonding Structure for Drop-Induced Short Prevention
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Solution Overview
Problem
Secondary batteries face issues with drop performance due to the impact force causing the separator to shrink, leading to short-circuiting between the positive and negative electrode plates, which is exacerbated by the relative sliding between the electrode assembly and the packaging bag.
Innovation Solution
The secondary battery design includes a first bonding member with opposing bonding surfaces securing the positive electrode plate and the packaging bag, and a specific arrangement of uncoated foil zones and separators to mitigate shrinkage and sliding, reducing the risk of short-circuiting and improving structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separator is positioned between the positive and negative electrode plates in a conventional winding structure, then the battery can function normally, but the separator shrinks under impact force causing short-circuiting and poor drop performance
Solution Approach 1:
The patent extracts the separator from its conventional position between the positive and negative electrode plates. Instead, the separator is positioned only between the negative electrode plate and the uncoated foil zone, removing it from the critical short-circuit risk area where impact forces cause shrinkage between opposite polarity plates.
Solution Approach 2:
The uncoated foil zone acts as an intermediary element between the positive and negative electrode plates. This foil zone serves as a buffer that prevents direct contact between the separator and the positive electrode plate, reducing the risk of short-circuiting when the separator shrinks under impact.
2Reliability
If the electrode assembly is loosely positioned in the packaging bag, then the battery structure is simple, but the electrode assembly slides relative to the packaging bag under impact causing separator shrinkage and short-circuiting
Solution Approach 1:
The patent applies preliminary action by pre-positioning the electrode assembly in a specific configuration within the packaging bag before impact occurs. The electrode assembly is arranged with the separator positioned in the uncoated foil zone area, preparing it to withstand impact forces without sliding or causing short-circuits.
3Reliability
If the positive electrode plate extends beyond the negative electrode plate with an uncoated foil zone, then the separator can be repositioned to improve drop performance, but the electrode assembly structure becomes more complex
Solution Approach 1:
The uncoated foil zone serves multiple functions: it acts as an electrical insulator preventing short-circuits, provides a positioning structure for the separator, and serves as a buffer zone that absorbs impact forces. This multi-functionality reduces the need for additional components, keeping the overall structure relatively simple while improving drop performance.
Data Source
AI summary
A secondary battery includes an electrode assembly, a packaging bag, and a first bonding member. The electrode assembly includes a positive electrode plate, a separator, and a negative electrode plate that are arranged in a winding manner. An end portion of the positive electrode plate and an end portion of the separator extend beyond an end portion of the negative electrode plate, and a first uncoated foil zone is provided at a portion at which the positive electrode plate extends beyond the negative electrode plate. An outermost circle of a first straight segment includes one layer of a first uncoated foil zone. An inner circle of the first straight segment includes the positive electrode plate close to the first uncoated foil zone and at least one layer of the separator located between the first uncoated foil zone and the positive electrode plate.