Flat Wound Electrode Body Residue Management
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face increased resistance due to excess nonaqueous electrolytic solution residue accumulating in the wound electrode body, leading to potential short-circuiting and decreased performance.
Innovation Solution
A flat wound electrode body configuration with squashed end portions and a specific shape to prevent excess solution accumulation, ensuring the residue is discharged outside, reducing electrode resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an excess amount of nonaqueous electrolytic solution is supplied into the battery case, then the electrode body may be adequately impregnated, but the residue accumulates in the lower portion of the wound electrode body causing increased resistance
Solution Approach 1:
The second R portion is pre-formed with a specific curved shape and positioned at the bottom side of the battery case before electrolyte filling. This preliminary structural configuration creates a designated pathway that guides excess electrolyte residue away from the electrode body during the filling process, preventing accumulation-induced resistance increases.
Solution Approach 2:
The second R portion acts as an intermediary structure between the electrolyte filling process and the electrode body. It mediates the flow of excess electrolyte by providing a curved pathway that directs residue outward, preventing direct contact and accumulation on the electrode surfaces that would otherwise increase resistance.
2Reliability
If the second R portion is positioned at the bottom side of the battery case, then excess electrolyte residue is effectively discharged outward, but the structure becomes more complex
Solution Approach 1:
The second R portion is formed with a specific curved shape (circular arc configuration) that naturally guides excess electrolyte residue outward toward the battery case opening. This curvature leverages gravitational and capillary forces to achieve effective residue discharge without requiring additional active components or complex mechanisms.
Solution Approach 2:
Only the second R portion (at the bottom side) is given the specific curved shape and positioning function, while the first R portion and central portion maintain their conventional structures. This localized differentiation achieves residue discharge functionality without unnecessarily complicating the entire electrode body structure.
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 configuration effectively suppresses the accumulation of excess electrolyte residue, thereby reducing electrical resistance and preventing short-circuiting, enhancing the battery's performance and reliability.
Implementation Method 1
the residue of the nonaqueous electrolytic solution is appropriately discharged to the outside of a wound electrode body (an excess amount of the nonaqueous electrolytic solution is not penetrated into or held in the wound electrode body)
Data Source
AI summary
Provided is a nonaqueous electrolyte secondary battery including a flat wound electrode body. The flat wound electrode body has a flat portion, a first R portion, and a second R portion. The second R portion is provided on a bottom side of a battery case when a nonaqueous electrolytic solution is put into the battery case at least in a battery construction step. Opposite end portions of the second R portion in the winding axial direction are squashed in a thickness direction of the electrode body to a larger extent than opposite end portions of the first R portion in the winding axial direction.