Composite Current Collector Safety Coating for Short-Circuit Isolation
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Solution Overview
Problem
Existing safety coatings for lithium-ion battery current collectors fail to simultaneously enhance battery safety, maintain energy density, and ensure superior long-term cycling and high-rate discharge performance.
Innovation Solution
A safety coating composed of 30 to 50 parts of a metal-doped lithium manganese iron phosphate material, 1 to 5 parts of a conductive agent, 10 to 30 parts of a binder, and 10 to 20 parts of a solvent, applied to a current collector substrate, with specific thicknesses and particle sizes, to provide electrical isolation and high resistance during short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety coating is applied to isolate electrodes and provide high resistance during short circuits, then battery safety is improved, but energy density is reduced
Solution Approach 1:
The patent optimizes the thickness parameter of the safety coating to 2-5 μm, which is sufficiently thin to minimize impact on energy density while sufficiently thick to provide effective electrical isolation and safety protection during short circuits. This parameter optimization resolves the contradiction between safety and energy density.
Solution Approach 2:
The patent uses a composite coating material system consisting of phosphate material (LiFe1-x-yMn x M y PO 4) as the base, combined with conductive agents, binders, and solvents. This composite structure provides both the electrical isolation function for safety and maintains sufficient conductivity and adhesion properties, thereby balancing safety enhancement with minimal energy density loss.
2Reliability
If a safety coating is applied to improve battery safety, then safety performance is enhanced, but long-term cycling performance deteriorates
Solution Approach 1:
The patent employs a composite coating system where phosphate material provides safety isolation, conductive agents maintain electrical conductivity for cycling performance, and binders ensure strong adhesion. This multi-component composite structure allows the coating to simultaneously provide safety protection while maintaining good long-term cycling performance.
Solution Approach 2:
The coating is applied with specific local properties: phosphate material concentrated for safety isolation, conductive agents distributed to maintain conductivity, and binders positioned to ensure adhesion. This localized functional distribution allows the coating to provide safety protection without significantly impacting long-term cycling performance.
3Reliability
If a safety coating is applied to enhance safety, then resistance during short circuits is improved, but high-rate discharge capability deteriorates
Solution Approach 1:
The patent combines phosphate material for high resistance during short circuits with conductive agents that maintain electrical conductivity. This composite structure enables the coating to provide both high resistance for safety and sufficient conductivity for high-rate discharge capability.
Solution Approach 2:
The patent optimizes the thickness parameter to 2-5 μm and controls the composition ratios of conductive agents and phosphate material, achieving a balance where the coating provides sufficient resistance during short circuits while maintaining adequate electrical conductivity for high-rate discharge performance.
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 coating effectively improves safety by preventing direct electrode contact, maintains high energy density, and enhances long-term cycling and high-rate discharge performance without significant impact on energy density.
Implementation Method 1
the safety coating therefore can effectively improve the safety performance of the battery without changing the material system, the electrode sheet performance and the product performance
Data Source
AI summary
A safety coating, a preparation method thereof and a composite current collector are provided. The safety coating includes, by weight parts, 30 to 50 parts of a phosphate material, 1 to 5 parts of a conductive agent, 10 to 30 parts of a binder, and 10 to 20 parts of a solvent. The phosphate material has a chemical formula of LiFe1-x-yMnxMyPO4, in which 0<x<1, 0<y≤0.1, 0<x+y<1, and M is selected from at least one of Cr, Mg, Ti, Al, Zn, W, Nb, or Zr.