Oxide-Coated Electrode Tab Edges for Battery Short-Circuit Suppression
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Solution Overview
Problem
Laser cutting of electrode plates in secondary batteries can lead to metal pieces peeling off and causing internal short circuits due to mixing between positive and negative electrodes, either during cutting or after dissolution in the electrolytic solution, compromising battery safety.
Innovation Solution
The electrode plate design includes an oxide film region on the electrode tab with a thickness of 40 nm to 200 nm, extending 0.01 mm to 0.2 mm from the outer end, which insulates and inactivates any peeled metal pieces, preventing internal short circuits. Additionally, a second region with decreasing oxide film thickness is formed to enhance attachment and prevent peeling, and a copper or copper alloy core is used for improved effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser cutting is performed to cut out the electrode plate from the electrode precursor, then the electrode plate can be manufactured with desired size and shape, but metal pieces may peel off from the electrode core and cause internal short circuits
Solution Approach 1:
An oxide film is formed on the electrode core surface at the tab outer end before the electrode plate is assembled into the battery. This preliminary oxidation creates an insulating layer that prevents metal pieces from conducting electricity if they peel off during laser cutting or handling, thereby eliminating the internal short circuit risk while maintaining manufacturing precision
Solution Approach 2:
The potential harm of metal piece peeling during laser cutting is converted into a benefit by intentionally forming an oxide film in advance. The oxide film, which would normally be considered a surface defect or impurity, is instead utilized as a protective insulating layer that prevents the peeled metal pieces from causing internal short circuits
2Reliability
If the electrode tab is made with exposed electrode core for electrical connection, then electrical conductivity is improved, but metal pieces can easily peel off and cause safety issues
Solution Approach 1:
The electrode tab is designed with non-uniform oxide film distribution: the outer end portion has a thick oxide film (5 nm to 200 nm) for insulation, while the inner portion near the electrode plate body maintains minimal or no oxide film for good electrical conductivity. This local differentiation allows the tab to simultaneously achieve both electrical connectivity and safety
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 configuration effectively suppresses internal short circuits by insulating and inactivating metal pieces, enhancing the safety and reliability of secondary batteries by preventing electrical conduction and dissolution issues.
Implementation Method 1
a first region having an oxide film of the metal material with a thickness of 40 nm to 200 nm is formed in a region of at least 0.01 mm to 0.2 mm from an outer end side of the electrode tab toward the inside
Implementation Method 2
a first region having an oxide film of the metal material with a thickness of 40 nm to 200 nm is formed in a region of at least 0.01 mm to 0.2 mm from an outer end side of the electrode tab toward the inside
Data Source
AI summary
According to the present disclosure, a technique capable of suppressing an internal short circuit caused by a peeled metal piece and obtaining a safer secondary battery is provided. An electrode plate (negative electrode plate) disclosed herein includes a negative electrode core including copper or a copper alloy, a negative electrode active material layer applied to a surface of the negative electrode core, and a negative electrode tab protruding to the outside from one end side in a width direction. In the negative electrode plate, a first region having an oxide film having a thickness of 40 nm to 200 nm is formed in a region of 0.01 mm to 0.2 mm from an outer end side of the negative electrode tab toward the inside in the width direction, and the first region 22t1 extends along the outer end side 22ta of the negative electrode tab 22t. As a result, a metal piece that can be peeled off from the negative electrode tab 22t can be insulated and inactivated in advance, so that an internal short circuit due to the peeled metal piece can be suppressed.