UV-Cured Corrosion Layer for Cylindrical Battery Weld Damage
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Solution Overview
Problem
Conventional cylindrical secondary batteries face issues with high resistance and corrosion of the battery can due to damaged metal plated layers during welding, which are not adequately addressed by existing corrosion inhibition methods.
Innovation Solution
A manufacturing method involving the application of ultraviolet-curable resin with low viscosity (1 cP to 5000 cP) to form a corrosion prevention layer on the damaged metal plated layer, which is cured using ultraviolet rays to prevent exposure to corrosion factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a corrosion-preventing layer is formed by a known method (electroless plating, electroplating, chemical vapor deposition, or physical vapor deposition) on a steel plate for use as a current collector in a lithium ion secondary battery, then the layer can provide some corrosion resistance, but the layer contains pinholes and coarse grains that cause poor adhesion to the active material layer, leading to peeling during battery assembly and poor cycle characteristics
Solution Approach 1:
The patent changes the chemical composition parameters of the corrosion-preventing layer by controlling the atomic ratios of Al, Si, and P elements within specific ranges (Al: 70-90 at%, Si: 5-20 at%, P: 5-20 at%). This compositional parameter optimization enables the formation of a layer with fine grains and reduced pinholes, thereby improving both adhesion and surface quality without requiring multiple processing steps.
Solution Approach 2:
The patent creates a composite corrosion-preventing layer by combining multiple elements (Al, Si, P) in specific proportions to form an alloy-based protective layer. This composite structure leverages the synergistic effects of different elements: Al provides base corrosion resistance, Si refines grain structure, and P reduces pinhole formation. The resulting composite material achieves superior adhesion and surface quality compared to single-element coatings.
2Reliability
If a corrosion-preventing layer is formed on a steel plate to prevent corrosion in lithium ion secondary batteries, then corrosion resistance is improved, but the layer formation process is complex and requires multiple steps, increasing manufacturing complexity
Solution Approach 1:
The patent merges multiple functions into a single corrosion-preventing layer formed by one-step sputtering. The layer simultaneously provides corrosion resistance, adhesion promotion, and surface quality improvement through the combined action of Al, Si, and P elements. This eliminates the need for separate treatment steps that would otherwise be required to achieve each function individually, thereby simplifying the manufacturing process while maintaining reliability.
3Strength
If a corrosion-preventing layer with fine grains and no pinholes is formed to improve adhesion and prevent peeling, then adhesion strength is improved, but the manufacturing process becomes more difficult and time-consuming
Solution Approach 1:
The patent incorporates Si and P elements into the corrosion-preventing layer composition before the sputtering process begins. These elements are pre-mixed in the target material at specific atomic ratios, so that during the single-step sputtering process, they are automatically deposited in the correct proportions to form fine grains and eliminate pinholes. This preliminary preparation of the target composition eliminates the need for subsequent heat treatment or annealing steps that would otherwise be required to achieve fine grain structure, thereby maintaining high productivity while improving adhesion strength.
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 method effectively prevents corrosion of the battery can, ensuring product integrity and safety under high-temperature high-humidity conditions, with a uniform and stable corrosion prevention layer that maintains physical properties and minimizes defects.
Implementation Method 1
it has been found that a sputtering method using a target containing Al, Si, and P can be used to form a corrosion-preventing layer
Data Source
Figure 1(A)~1(C)
Figure 2(A)~2(C)
AI summary
The present specification relates to a manufacturing method of a corrosion prevention layer, and a manufacturing method of a corrosion prevention layer on a cylindrical secondary battery including a jelly-roll type electrode assembly having a structure in which a first electrode, a second electrode, and a separator interposed therebetween are wound in one direction based on a winding axis, a battery can accommodating the electrode assembly, and the battery can including a metal plated layer, and a connection lead plate joining the battery can and the electrode assembly, which includes: (A) applying a resin for the corrosion prevention layer to a portion where the metal plated layer is damaged at a welding portion formed by melting the connection lead plate and the battery can upon welding of an external bottom surface of the battery can; and (B) forming the corrosion prevention layer by curing the resin for the corrosion prevention layer by ultraviolet rays, in which the resin for the corrosion prevention layer includes one or more liquid materials, and the one or more liquid materials are ultraviolet curable, and have a viscosity of 1 cP to 5000 cP.