Cylindrical Battery Current Collector Joining Method
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Solution Overview
Problem
Small lithium ion secondary batteries face challenges in achieving high sealing properties and reliable low-resistive coupling between current collector leads and electrode terminals, leading to voltage drops and reduced battery capacity when extracting large currents.
Innovation Solution
A battery design where the first current collector lead is joined to the inner sidewall surface of a closed-end cylindrical metal case, and the second current collector lead is joined to a sealing member, with the sealing member sealing the opening of the metal case, ensuring reliable electrical coupling and enhanced sealing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a columnar electrode rod is inserted into the through-hole and pressed onto the bottom with high pressure to achieve reliable electrical coupling, then the electrical coupling between the negative electrode current collector plate and the closed-end cylindrical body is improved, but the battery capacity is reduced due to the need for a greater rod radius which reduces the amount of positive and negative electrodes
Solution Approach 1:
The invention extracts and eliminates the columnar electrode rod component from the traditional battery structure. Instead of using a rod inserted through the winding core, the patent directly welds the negative electrode current collector plate to the bottom of the closed-end cylindrical body, removing the intermediary rod that consumed battery capacity and caused welding reliability issues.
Solution Approach 2:
The invention merges the functions of the columnar electrode rod and the negative electrode current collector plate into a single integrated structure. The negative electrode current collector plate itself serves as both the electrical conductor and the welding element that directly contacts the battery can bottom, eliminating the need for a separate rod component.
2Quantity of substance
If a fine columnar electrode rod is used to maintain battery capacity, then the battery capacity is improved, but the electrical coupling becomes insufficient due to reduced pressure on the rod
Solution Approach 1:
The invention removes the columnar electrode rod entirely from the structure, eliminating the fundamental conflict between rod size and welding pressure. By directly welding the current collector plate to the battery can bottom without an intermediary rod, the system achieves both high capacity and reliable electrical coupling 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 design increases the sealing properties and provides reliable low-resistive coupling between current collector leads and electrode terminals, enhancing the voltage and capacity of the battery.
Implementation Method 1
By flowing a current between the electrode rod and the electrode piece, the negative electrode current collector plate and the closed-end cylindrical body are resistance-welded
Data Source
AI summary
A battery includes a first electrode plate, a second electrode plate, a separator interposed between the first and second electrode plates, a closed-end cylindrical metal case accommodating these three elements, and a sealing member sealing an opening of the metal case with an insulating member interposed therebetween. The first and second electrode plates are wound with the separator interposed therebetween to form a wound electrode group. A center axis portion of the wound electrode group is substantially the same as a center axis of a cylinder of the metal case, and contains no power-generating element. A first current collector lead coupled to the first electrode plate extends toward the opening of the metal case, and joined to an inner sidewall surface of the metal case. A second current collector lead coupled to the second electrode plate extends toward the opening of the metal case, and joined to the sealing member.