Non-aqueous Electrolyte Battery Wound Electrode Gap Reduction
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face performance reduction due to variations in current density causing local electrical resistance differences, leading to ion deposition as metal on the negative electrode, which can be exacerbated by gaps in the wound electrode body.
Innovation Solution
The battery design includes a wound electrode body with specific positioning and bending points of separators and electrodes, ensuring that the winding starting and ending ends of the negative and positive electrodes are positioned close to the bending end straight line, reducing gaps and maintaining consistent current density, thereby preventing ion deposition as metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gaps are present in the wound electrode body, then the battery structure is simpler to manufacture, but variations in current density occur leading to local electrical resistance differences and ion deposition as metal
Solution Approach 1:
The patent changes the geometric parameters of the electrode body by introducing specific curved surface portions with defined radii of curvature (R1, R2) and positioning relationships. These parameter changes eliminate gaps in the wound electrode body while maintaining manufacturability, preventing current density variations and metal deposition that would otherwise occur with flat surface configurations
Solution Approach 2:
The patent applies curvature to the electrode body surfaces by defining curved surface portions with specific radii of curvature. The first curved surface portion has radius R1 and the second has radius R2, where these curved surfaces replace flat surfaces to eliminate gaps. This spherical/curved geometry ensures uniform contact between wound layers, preventing the harmful effects of gaps while preserving ease of manufacturing through standardized curved components
2Volume of moving object
If the winding starting and ending ends are positioned far from the bending end straight line, then the electrode body has more space, but gaps occur between electrodes and separators causing current density variations
Solution Approach 1:
The patent establishes specific parameter relationships between the positioning of winding ends and the bending end straight line. By defining distances A, B, and X that satisfy A < B < X and specific ratio relationships, the patent optimizes the positioning to eliminate gaps while maintaining appropriate space. This parametric approach ensures precise positioning without excessive space requirements
Solution Approach 2:
The patent transitions from considering only linear positioning to incorporating spatial relationships in multiple dimensions. By defining positions relative to the bending end straight line and considering distances in different directions (A, B, X), the patent achieves precise gap elimination through multi-dimensional positioning control rather than simple linear arrangement
Data Source
AI summary
A non-aqueous electrolyte secondary battery includes a wound electrode body in which a first and a second separator, and a negative and a positive electrode body are stacked and wound. The wound electrode body has two R portions and is positioned in a flat portion. In a cross section orthogonal to a winding axis, when a distance from a bending end straight line to the winding starting end of the negative electrode body in a reference direction is denoted by A, a distance from the bending end straight line to the winding starting end of the positive electrode body in the reference direction is denoted by B, and X represents a distance from the bending end straight line to the winding end of the negative electrode body in the reference direction in the cross section is denoted by X, A, B, and X satisfy Condition: A<B<X.