Dual-Layer Battery Electrode with Fluorinated Polymer for Nail Penetration Safety
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Solution Overview
Problem
Lithium-ion batteries are prone to fires and explosions due to internal short circuits caused by nail penetration, which limits their safety and application.
Innovation Solution
A battery design featuring a positive electrode plate with a dual-layer structure, where the underlying layer comprises a fluorinated polyolefin and/or chlorinated polyolefin polymer material, acting as a binder and PTC safety coating, effectively masking metal burrs and preventing internal short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-layer positive electrode structure is used, then manufacturing process is simple, but nail penetration safety is poor due to metal burrs causing internal short circuits
Solution Approach 1:
The positive electrode active material layer is divided into two distinct layers: an upper layer containing positive active material and a lower layer containing polymer material and conductive material. This segmentation allows each layer to perform its specific function - the upper layer provides electrochemical activity while the lower layer masks metal burrs and provides PTC safety, thereby improving nail penetration safety without requiring complex additional components.
Solution Approach 2:
Different regions of the positive electrode are given different material compositions and functions. The lower layer near the current collector is specifically designed with polymer material (content B%≥30%) and conductive material (content C%≥5%) to mask metal burrs and provide PTC effect, while the upper layer focuses on electrochemical performance. This local differentiation resolves the safety issue without making the entire electrode structure complex.
2Reliability
If polymer material content is increased to mask metal burrs, then nail penetration safety improves, but electrical conductivity may deteriorate
Solution Approach 1:
The patent optimizes the content parameters of multiple materials to balance safety and conductivity. The polymer material content is set at B%≥30% (providing burr masking and PTC safety), conductive material at C%≥5% (maintaining electrical conductivity), and positive active material at A%≤65% (ensuring electrochemical performance). These parameter changes collectively resolve the contradiction between safety and conductivity.
Solution Approach 2:
The lower layer is designed as a composite material system combining polymer material (for safety and burr masking), conductive material (for electrical conductivity), and positive active material (for electrochemical function). This composite structure allows the materials to complement each other - the polymer provides safety, the conductive material ensures conductivity, and the active material maintains performance, thereby resolving the contradiction between safety improvement and conductivity maintenance.
3Reliability
If dual-layer structure with optimized material content is used, then nail penetration safety and electrical properties improve, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple functions into the lower layer of the existing positive electrode structure. The lower layer simultaneously performs burr masking, PTC safety protection, and maintains electrical conductivity through its composite composition of polymer material, conductive material, and positive active material. This merging approach improves safety without requiring separate additional components or complex multi-step manufacturing processes.
Solution Approach 2:
The lower layer is designed as a multi-functional component that performs multiple roles: masking metal burrs to prevent short circuits, providing PTC safety response to thermal runaway, and maintaining electrical conductivity through conductive material. This multi-functionality allows a single structural modification to address multiple safety concerns simultaneously, improving nail penetration safety without proportionally increasing manufacturing complexity.
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 dual-layer structure enhances nail penetration safety by preventing internal short circuits and thermal runaway, while also improving electrical properties and manufacturing efficiency.
Implementation Method 1
the first polymer material comprises fluorinated polyolefin and/or chlorinated polyolefin polymer material
Implementation Method 2
acting as a binder and PTC safety coating, effectively masking metal burrs and preventing internal short circuits
Data Source
AI summary
This application relates to a battery comprising a positive electrode plate, a separator, and a negative electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and at least two layers of positive active material coated on at least one surface of the positive electrode current collector, and wherein an underlying positive active material layer in contact with the positive electrode current collector comprises a first positive active material, a first polymer material and a first conductive material; and wherein an upper positive active material layer in contact with the underlying positive active material layer and away from the positive electrode current collector comprises a second positive active material, a second polymer material and a second conductive material, and the first polymer material comprises fluorinated polyolefin and/or chlorinated polyolefin polymer material. The battery has good safety and improved electrical properties.