Rounded Current Collecting Lead for Battery Internal Resistance
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Solution Overview
Problem
Conventional alkaline secondary batteries face challenges in achieving high-rate discharge characteristics due to high internal resistance, particularly when using thin and long positive electrode ribbons, which increase internal resistance and risk of internal short-circuits under compressive loads.
Innovation Solution
A current collecting lead with rounded corner portions is interposed between the sealing body and the current collector, allowing for deformation under compressive loads to prevent the positive electrode current collector from pressing the electrode group, thus reducing the risk of internal short-circuits and maintaining a good high-rate discharge characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a thin and long positive electrode ribbon is used, then the ease of welding to the sealing body is improved, but the internal resistance increases and the risk of internal short-circuit increases
Solution Approach 1:
The current collecting lead is divided into multiple functional segments: a first current collecting portion for welding to the positive electrode current collector, a second current collecting portion for welding to the sealing body, and an intermediate portion connecting them. This segmentation allows each portion to be optimized independently - the first portion can be thin for easy welding to the electrode, while the second portion can be thicker for lower resistance, and the intermediate portion can be designed with appropriate dimensions to prevent short-circuits.
Solution Approach 2:
Different portions of the current collecting lead have different local properties: the first current collecting portion has smaller dimensions suited for welding to the positive electrode current collector, while the second current collecting portion has larger dimensions suited for welding to the sealing body and providing lower electrical resistance. The intermediate portion has specific length and width parameters that balance flexibility and short-circuit prevention.
2Ease of operation
If the positive electrode ribbon is made thinner for ease of bending, then the ease of operation is improved, but the specific resistance increases
Solution Approach 1:
The current collecting lead has different local thicknesses: the first current collecting portion is thinner (0.01-0.05mm) to match the positive electrode current collector and facilitate welding, while the second current collecting portion is thicker (0.05-0.2mm) to reduce electrical resistance. The intermediate portion has controlled dimensions that provide sufficient flexibility for assembly while maintaining acceptable electrical properties.
3Ease of manufacture
If a long positive electrode ribbon is used, then the ease of welding to the sealing body is improved, but the internal resistance increases
Solution Approach 1:
The current collecting lead is segmented into a first portion for electrode connection, a second portion for sealing body connection, and an intermediate portion. This allows the intermediate portion to be optimized for length (5-20mm) to provide adequate flexibility for welding operations while keeping the overall electrical path short enough to maintain low internal resistance, thus resolving the contradiction between ease of welding and low internal resistance.
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 solution effectively reduces internal resistance and inhibits internal short-circuits, particularly in small-size batteries, by allowing the current collecting lead to deform and absorb compressive loads, thereby maintaining a good high-rate discharge characteristic.
Implementation Method 1
the current collecting lead is allowed to deform under compressive loads applied at the time of fitting the sealing body into the outer can or at the time of resistance spot welding of the current collector to the sealing body or outer can
Implementation Method 2
the current collecting lead is allowed to deform under compressive loads... thereby preventing the positive electrode current collector from pressing the electrode group
Data Source
AI summary
A current collecting lead is interposed between a sealing body and a positive electrode current collector for connecting the sealing body and the positive electrode current collector, the sealing body including a positive electrode terminal, the positive electrode current collector being attached to an electrode group, the current collecting lead including: a top wall portion positioned on the side of the sealing body; leg portions positioned on the side of the positive electrode current collector and that face the top wall portion; and a pair of side wall portions that extend between side edges of the top wall portion and side edges of the leg portions and that face each other, a first corner portion and a second corner portion formed by the top wall portion and the side wall portions and a third corner portion and a fourth corner portion formed by the leg portions and the side wall portions being rounded corners that are curved.