Wound Electrode Assembly Segmentation for Micro-Short Circuit Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The wound electrode assembly in lithium-ion secondary batteries can cause micro-short circuits due to the positive electrode active material dissolving and depositing on the negative electrode sheet during high temperature aging, leading to poor product yield and detection issues during inspection.
Innovation Solution
A lithium-ion secondary battery design with a wound electrode assembly where the positive and negative electrode current collector foils have spirally exposed edge portions divided and gathered into multiple parts at gaps excluding the central portion, preventing the positive electrode active material from dissolving and depositing on the negative electrode sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the exposed portion of the metal foil is divided and gathered into two sets at the winding center along the flat thickness direction, then the battery structure is compact and easier to manufacture, but micro-short circuits occur due to positive electrode active material dissolving and depositing on the negative electrode sheet at the starting end of winding
Solution Approach 1:
The exposed portion of the metal foil is divided into a first exposed portion and a second exposed portion along the width direction, with the first exposed portion being gathered into one piece and the second exposed portion being gathered into another piece. This segmentation prevents the positive electrode active material from dissolving and depositing on the negative electrode sheet, thereby resolving the micro-short circuit issue while maintaining manufacturing ease.
Solution Approach 2:
The division and gathering of the exposed portion is performed along the width direction of the metal foil, introducing a new dimensional approach to the traditional thickness-direction gathering method. This dimensional change effectively separates the positive and negative electrode contact paths, preventing micro-short circuits while preserving the compact battery structure.
2Device complexity
If the exposed portion of the metal foil is not divided but gathered into one piece, then the manufacturing process is simpler, but micro-short circuits occur during high temperature aging leading to poor product yield
Solution Approach 1:
The exposed portion is segmented into first and second exposed portions that are gathered separately, preventing the micro-short circuit phenomenon during high temperature aging. This segmentation increases manufacturing complexity slightly but dramatically improves product yield by eliminating defective products.
3Shape
If the exposed portion is divided and gathered at the winding center, then the battery has compact structure, but the positive electrode active material dissolves and deposits on the negative electrode sheet causing micro-short circuits that are detected during inspection
Solution Approach 1:
The exposed portion is divided into first and second exposed portions along the width direction and gathered separately, maintaining the compact battery shape while preventing the dissolution and deposition of positive electrode active material on the negative electrode sheet, thereby eliminating micro-short circuits.
Solution Approach 2:
The division is performed along the width direction rather than only in the thickness direction, creating a three-dimensional gathering structure that maintains compactness while preventing harmful material transfer between electrodes.
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 design effectively prevents micro-short circuits during high temperature aging, improving product yield by reducing defective product detection and ensuring stable battery performance.
Implementation Method 1
the positive electrode active material dissolves from the positive electrode sheet and deposits on the negative electrode sheet at the starting end of winding during, for example, high temperature aging before shipping
Data Source
AI summary
A lithium-ion secondary battery (10) includes a wound electrode assembly (40) having a positive electrode current collector foil (51) and a negative electrode current collector foil 61). An edge portion (52) of the positive electrode current collector foil (51) is exposed in a spiral form at one end of a winding axis (WL). An edge portion (62) of the negative electrode current collector foil (61) is exposed in a spiral form at the other end of the winding axis (WL). The spirally exposed edge portion (52) of the positive electrode current collector foil (51) is divided and gathered into a plurality of parts divided at at least one of a plurality of gaps (S), excluding a central portion (WC) containing the winding axis (WL), provided between wound layers of the positive electrode current collector foil (51) stacked in a direction orthogonal to the winding axis (WL). Likewise, the spirally exposed edge portion (62) of the negative electrode current collector foil (61) is divided and gathered into a plurality of parts divided at at least one of a plurality of gaps (S), excluding the central portion (WC) containing the winding axis (WL), provided between wound layers of the negative electrode current collector foil (61) stacked in a direction orthogonal to the winding axis (WL).