Battery Separator Structure for Metal Piece Detection and Output
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Solution Overview
Problem
Existing methods for detecting metal pieces attached to negative electrode plates in nonaqueous electrolyte secondary batteries are insufficient, leading to potential voltage failures during battery use.
Innovation Solution
The implementation of a nonaqueous electrolyte secondary battery design that includes a negative electrode active material layer with a puncture resistance of at least 0.60 N/mm, a porous resin separator with a thickness retention ratio of 91.8% to 93.0%, and a specific layer structure for the separator, which enhances detection sensitivity and reduces the risk of creep short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer (ceramic layer) is introduced between the negative electrode plate and separator to countermeasure metal pieces, then detection sensitivity for metal pieces is improved, but battery output decreases
Solution Approach 1:
The patent introduces a porous resin layer as an intermediary between the negative electrode plate and separator. This layer has specific pore size and distribution that allows it to interact with metal pieces while maintaining ion transport. The porous structure provides detection capability through changes in electrical properties when metal pieces are present, without requiring a dense ceramic protective layer that would block ion flow and reduce battery output.
Solution Approach 2:
The patent employs a porous resin layer with controlled porosity and pore size distribution. The porous structure enables the layer to detect metal pieces through electrical property changes while maintaining sufficient ion permeability for battery operation. The specific pore characteristics allow detection sensitivity improvement without the need for dense protective coatings that would compromise battery power output.
2Stability of the object's composition
If metal piece is attached to negative electrode plate in low-potential environment, then dissolution rate is very low, but detection by voltage drop test becomes difficult
Solution Approach 1:
The porous resin layer serves as a mediator that enhances detection of stable metal pieces on the negative electrode. Even when metal pieces remain stable and do not dissolve significantly in the low-potential environment, the porous resin layer provides an additional detection mechanism through electrical property changes, improving measurement precision for detecting these stable metal contaminants.
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes an electrode assembly and an electrolyte solution. The electrode assembly includes a laminated assembly. The laminated assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator separates the positive electrode plate and the negative electrode plate from each other. The separator includes a porous resin layer. The porous resin layer includes a polyolefin-based material. The negative electrode plate includes a negative electrode active material layer. The negative electrode active material layer includes negative electrode active material particles. The negative electrode active material layer is in direct contact with the porous resin layer. The negative electrode active material layer has a puncture resistance of more than or equal to 0.60 N/mm.