Battery Cell Current Collector for Airtight Dissimilar-Material Welding
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Solution Overview
Problem
Existing battery cells face issues with airtightness due to uneven thermal expansion during welding, leading to potential safety hazards and reduced performance.
Innovation Solution
The use of a current collecting member with a first connecting part made of the same material as the tab and a second connecting part made of the same material as the shell, ensuring both parts have the same coefficient of thermal expansion, which prevents cracking and maintains airtightness by allowing even shrinkage during cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If different materials are used for the current collecting member and shell, then electrical conductivity is improved, but airtightness deteriorates due to uneven thermal expansion during welding
Solution Approach 1:
The current collecting member is divided into two distinct parts: a first connecting part made of the same material as the tab (for electrical connection) and a second connecting part made of the same material as the shell (for airtight connection). This segmentation allows each part to be optimized for its specific function without compromise.
Solution Approach 2:
Different portions of the current collecting member are made of different materials according to their functional requirements. The first connecting part uses highly conductive material for electrical connection, while the second connecting part uses shell-matching material for airtight welding, achieving local optimization of material properties.
2Reliability
If welding is performed between dissimilar materials, then electrical connection is achieved, but cracking occurs due to uneven shrinkage during cooling
Solution Approach 1:
The welding process is segmented into two separate operations: welding the first connecting part to the tab, and welding the second connecting part to the shell. This avoids the problematic dissimilar material welding that causes cracking, while still achieving both electrical connection and structural integrity.
Solution Approach 2:
The first connecting part acts as an intermediary between the tab and the current collecting member, ensuring excellent electrical connection through material compatibility. The second connecting part acts as an intermediary between the current collecting member and the shell, ensuring welding integrity through material compatibility.
3Ease of manufacture
If a single-material current collecting member is used, then manufacturing is simplified, but electrical connection stability deteriorates due to thermal expansion mismatch
Solution Approach 1:
The current collecting member exhibits local quality with different materials in different regions. The first connecting part uses tab-matching material for stable electrical connection, while the second connecting part uses shell-matching material for stable structural connection, optimizing both connection stabilities simultaneously.
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 solution enhances the airtightness and safety of battery cells by preventing cracks at the welding points, improving electrical connection stability and overall battery performance.
Implementation Method 1
the second connecting part and the shell are made of the same material. Therefore, the second connecting part and the shell have the same coefficient of thermal expansion, and in the process of welding the second connecting part to the shell, atoms from the second connecting part and the shell will enter each other. In the cooling process, due to the same coefficient of expansion, the welding position shrinks evenly, and cracks will not occur at the welding position due to uneven shrinkage
Implementation Method 2
The first connecting part of the current collecting member is used to be welded to the tab, and the first connecting part and the tab are made of the same material. Therefore, the first connecting part and the tab have the same coefficient of thermal expansion, and in the process of welding the first connecting part to the tab, atoms from the first connecting part and the tab will enter each other. In the cooling process, due to the same coefficient of expansion, the welding position shrinks evenly, so that the tab and the current collecting member form fine electrical connection and improve the conduction stability
Data Source
AI summary
A battery cell, a battery, an electrical device, and a device and method for manufacturing a battery cell are described. The battery cell includes a shell, an electrode assembly, and a current collecting member, where the electrode assembly is accommodated in the shell, and the electrode assembly is provided with a tab; the current collecting member includes a first connecting part and a second connecting part which are connected, the first connecting part is used to be welded to the tab, and the second connecting part is used to be welded to the shell; and the first connecting part and the second connecting part are made of different materials, the first connecting part and the tab are made of the same material, and the second connecting part and the shell are made of the same material.