Dual-Layer Battery Electrode with Fluorinated Polymer for Nail Penetration Safety
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Solution Overview
Problem
High-nickel ternary materials used in lithium-ion batteries suffer from poor thermal stability and safety hazards, particularly during abnormal conditions like nail penetration, leading to potential fires and explosions due to internal short circuits.
Innovation Solution
A battery design featuring a positive electrode plate with a dual-layer structure, where the underlying active material layer acts as a binder and PTC safety coating, comprising fluorinated polyolefin and/or chlorinated polyolefin polymer materials, effectively masking metal burrs and preventing internal short circuits, while the upper layer maintains conventional composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-nickel ternary materials are used as positive electrode materials, then energy density is improved, but thermal stability deteriorates and safety hazards increase
Solution Approach 1:
The positive electrode active material layer is divided into two distinct layers: a lower layer in contact with the current collector and an upper layer in contact with the lower layer. The lower layer has different composition ratios of positive active material, polymer material, and conductive material compared to the upper layer, allowing each layer to perform specialized functions that collectively improve both energy density and thermal stability.
Solution Approach 2:
Different regions of the positive electrode active material layer are assigned different compositions and properties. The lower layer contains specific ratios of materials optimized for thermal stability and safety, while the upper layer is optimized for energy density and electrochemical performance, allowing each region to have the quality needed for its specific function.
2Quantity of substance
If high-nickel ternary materials are used, then capacity is improved, but nail penetration safety deteriorates due to internal short circuits
Solution Approach 1:
The lower layer of the positive electrode active material layer serves as a protective interface between the current collector and the upper layer. This lower layer is designed with specific material composition to prevent direct contact between metal burrs generated during nail penetration and the high-nickel ternary material, thereby cushioning against the harmful effects before they can cause internal short circuits.
Solution Approach 2:
The lower layer acts as an intermediary between the current collector and the upper layer containing high-nickel ternary material. This intermediate layer prevents direct interaction between metal burrs and the reactive high-nickel material, mediating the potential harmful effects of nail penetration and preventing internal short circuits.
3Ease of manufacture
If conventional single-layer structure is used, then manufacturing is simple, but safety performance deteriorates under abnormal conditions
Solution Approach 1:
The positive electrode active material layer is segmented into two layers with different compositions, where the lower layer provides safety functions and the upper layer provides energy density functions. This segmentation allows the battery to achieve improved safety performance under abnormal conditions while maintaining reasonable manufacturing complexity through a systematic coating process.
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 significantly enhances nail penetration safety and thermal stability, reducing the risk of fires and explosions, and improves electrical properties by effectively managing temperature resistance and adhesion.
Implementation Method 1
the underlying positive active material layer in contact with the positive electrode current collector acts as a binder and PTC safety coating
Implementation Method 2
the underlying positive active material layer in contact with the positive electrode current collector acts as a binder
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.