Secondary Battery Electrode Taper Exposure for Positioning
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Solution Overview
Problem
The existing lithium ion secondary batteries face challenges in maintaining precision positioning between the cathode and anode mixture layers due to the opaque porous insulation layer, which hinders accurate lamination and rolling processes.
Innovation Solution
The battery design incorporates a separator between the cathode and anode, with a metal foil exposure portion and a taper portion of the mixture layer exposed from the insulation layer, allowing for improved positioning precision by visually recognizing the end positions of the mixture layers during the rolling process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an opaque porous insulation layer is used to suppress separator shrinkage and expansion, then safety is improved, but positioning precision between cathode and anode mixture layers deteriorates
Solution Approach 1:
The electrode structure is segmented into distinct functional zones: the mixture layer, the insulation layer, and the foil exposure portion. This segmentation allows the insulation layer to provide safety coverage while the exposed foil portions serve as positioning markers, resolving the contradiction between safety and positioning precision.
Solution Approach 2:
The foil exposure portion acts as an intermediary element between the insulation layer and the positioning requirement. It provides visual reference for positioning while the insulation layer maintains safety, allowing both functions to coexist without direct conflict.
2Reliability
If the insulation layer covers the entire mixture layer, then safety is improved, but the end position of the mixture layer becomes undetectable
Solution Approach 1:
The foil exposure portion extracts the detection function from beneath the insulation layer. By intentionally leaving portions of the metal foil exposed at the ends of the mixture layer, the system maintains continuous insulation coverage while providing detectable markers for end position identification.
Solution Approach 2:
The metal foil exposure portions provide visual contrast against the opaque insulation layer, creating detectable visual markers. This color/reflectivity difference enables easy detection of the mixture layer boundaries during manufacturing processes.
3Device complexity
If positioning precision is degraded, then manufacturing complexity is reduced, but battery performance deteriorates due to capacity degradation
Solution Approach 1:
The structure provides self-positioning capability through the foil exposure portions. These exposed portions automatically serve as alignment markers during the rolling process, eliminating the need for complex external positioning systems or additional manufacturing steps, thus maintaining simplicity while ensuring precision.
Data Source
AI summary
Disclosed is a secondary battery obtained by rolling a cathode 31 and an anode 32 by interposing separators 33 and 34. The cathode 31 and the anode 32 have metal foils 31a and 32a, mixture layers 31b and 32b formed on the metal foils 31a and 32a, and foil exposure portion 31c and 32c that expose the metal foils 31a and 32a and are provided in one side in the width direction, respectively. The cathode 31 or the anode 32 has an insulation layer 35 that covers the mixture layers 31b and 32b, and a tip of a taper portion 32t of the mixture layer 32b, where the taper portion 32t is adjacent to the foil exposure portions 31c and 32c and has a thickness gradually reduced toward the foil exposure portions 31c and 32c, is exposed from the insulation layer 35.