Lithium Secondary Battery Tab Bonding for Low-Resistance Laminate Connection
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Solution Overview
Problem
Existing methods for connecting current collectors in lithium secondary batteries result in increased resistance and decreased productivity due to the need for folding and mechanical bonding, leading to deteriorated output characteristics.
Innovation Solution
A lithium secondary battery design that includes a first and second laminate with insulating and conductive layers, separated by a metal sheet and bonded via electrode tabs with specific bonding marks, allowing for efficient electrical connection without mechanical folding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current collectors are folded and laminated to connect metal layers separated by resin layers, then electrical conduction can be obtained between electrodes and electrode tabs, but device complexity and manufacturing difficulty increase due to the need for folding and mechanical bonding
Solution Approach 1:
The current collector is divided into a body portion (with electrode) and a protruding portion (without electrode). The protruding portion extends through the resin layer to the other side, eliminating the need for folding and creating separate connection points for electrical conduction while maintaining structural simplicity.
Solution Approach 2:
The protruding portion of the current collector acts as an intermediary element that bridges the gap between the electrode and the external connection point. It extends through the insulating resin layer to provide a direct electrical pathway without requiring complex folding or additional bonding mechanisms.
2Reliability
If current collectors are folded and mechanically bonded to connect electrodes, then electrical connection is achieved, but productivity decreases due to complex manufacturing processes
Solution Approach 1:
The current collector is segmented into functional zones: the body portion supports the electrode, while the protruding portion provides external connection. This segmentation allows for simpler assembly processes without folding or complex mechanical bonding, thereby improving manufacturing efficiency.
Solution Approach 2:
The protruding portion is pre-formed as an integral part of the current collector during the rolling process, before assembly. This preliminary formation eliminates the need for subsequent folding and bonding operations, streamlining the manufacturing process and improving productivity.
3Reliability
If traditional current collector designs are used with folding and mechanical bonding, then electrode connections are made, but resistance increases leading to deteriorated output characteristics
Solution Approach 1:
By separating the current collector into a body portion and a protruding portion, the design creates a direct, uninterrupted electrical pathway. This eliminates contact resistance from folding joints and mechanical bonding interfaces, reducing overall resistance and improving output characteristics.
Solution Approach 2:
The protruding portion serves as a low-resistance intermediary conductor that provides a direct electrical pathway from the electrode through the resin layer to the external connection point, minimizing energy loss compared to folded and bonded configurations.
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 suppresses the decrease in output characteristics and improves productivity by reducing resistance and simplifying the manufacturing process.
Implementation Method 1
the electrode tab having a first bonding mark and a second bonding mark, the first bonding mark being a bonding mark due to bonding of the electrode tab with the first end part, the first portion of the metal sheet, and the second end part
Data Source
Figure 1
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Figure 2B
AI summary
There is provided a technique for suppressing a decrease in output characteristics and productivity of a lithium secondary battery. A lithium secondary battery is provided. The lithium secondary battery includes (a) a first laminate including a first end part, (b) an intermediate laminate, (c) a second laminate including a second end part, (d) a metal sheet including a first portion that overlaps with the first end part and the second end part in a case of being viewed from the lamination direction and a second portion that does not overlap with the first end part and the second end part in a case of being viewed from the lamination direction, and (e) an electrode tab that is electrically connected to the first laminate and the second laminate. The electrode tab has a first bonding mark and a second bonding mark. The first bonding mark is a bonding mark due to bonding of the electrode tab and the first end part, the first portion, and the second end part of the metal sheet. The second bonding mark is a bonding mark due to bonding of the electrode tab and the second portion of the metal sheet.