Flame-Retardant Current Collector Coating for High-Nickel Batteries
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Solution Overview
Problem
Rechargeable lithium batteries face safety issues due to the low thermal safety of high nickel positive electrode materials, leading to battery deterioration and reduced energy density, as well as increased volume and weight when safety functional materials are introduced to mitigate these problems.
Innovation Solution
A current collector with a functional layer comprising a flame retardant, conductive material, and binder is used between the substrate and the electrode active material layer, enhancing safety, conductivity, and adherence while minimizing energy density loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high nickel positive electrode material is used to achieve high energy density, then energy density is improved, but thermal safety deteriorates leading to battery safety issues
Solution Approach 1:
A functional layer is introduced as an intermediary between the high nickel positive electrode material and the electrolyte. This functional layer includes flame retardant particles (such as melamine polyphosphate or ammonium polyphosphate) that act as mediators to suppress thermal runaway reactions, thereby improving thermal safety without sacrificing the high energy density benefits of the high nickel material
Solution Approach 2:
The functional layer is constructed as a composite material system combining flame retardant particles, conductive materials (such as carbon black or acetylene black), and binder polymers. This composite structure provides both thermal safety through flame retardancy and electrical conductivity through the conductive material network, resolving the contradiction between safety and performance
2Reliability
If safety functional materials are introduced to improve thermal runaway resistance, then battery safety is improved, but volume and weight increase thus deteriorating energy density
Solution Approach 1:
The functional layer is designed as a thin film coating on the current collector, with a thickness optimized to provide sufficient flame retardant protection while minimizing volume occupation. The thin film structure ensures that safety functionality is achieved without significantly increasing battery volume or weight, thereby maintaining high energy density
Solution Approach 2:
The flame retardant functionality is localized to the functional layer at the electrode-electrolyte interface, rather than distributing safety materials throughout the entire battery structure. This localized approach provides safety where it is most needed (at the interface where thermal runaway initiates) while minimizing overall volume and weight increases
3Reliability
If safety functional materials are introduced to improve thermal runaway resistance, then battery safety is improved, but battery characteristics deteriorate due to increased resistance
Solution Approach 1:
The functional layer is constructed as a composite material system combining flame retardant particles (such as melamine polyphosphate or ammonium polyphosphate) with conductive materials (such as carbon black, acetylene black, or conductive polymers). This composite structure provides both thermal safety through flame retardancy and electrical conductivity through the conductive material network, resolving the contradiction between safety and 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 solution improves battery safety, prevents deterioration, and maintains energy density by effectively suppressing temperature increases and ensuring excellent adhesion between the current collector and electrode active material layer.
Implementation Method 1
the functional layer includes a flame retardant, a conductive material, and a binder
Implementation Method 2
the functional layer includes a flame retardant, a conductive material, and a binder
Implementation Method 3
the functional layer includes a flame retardant, a conductive material, and a binder
Data Source
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AI summary
A current collector for a rechargeable lithium battery according to an embodiment includes a substrate; and a functional layer on the substrate, wherein the functional layer includes a flame retardant, a conductive material, and a binder.