Multilayer Electrode Coating for Flame-Retardant Battery Impregnation
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to the generation of oxygen and short circuits in high-temperature environments, and conventional flame retardant electrolytes have poor impregnation and high interfacial resistance, leading to non-uniform reactions and dendrite formation.
Innovation Solution
An electrode assembly with a coating layer comprising multiple layers, including oxide-based solid electrolyte and ceramic particles with specific zeta potentials, enhances electrolyte impregnation and prevents short circuits, using a flame retardant electrolyte with a flash point of 100°C or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin-based separator is used to ensure electrical insulation between positive and negative electrodes, then insulation performance is improved, but high-temperature stability deteriorates due to shrinkage
Solution Approach 1:
The separator is constructed as a composite material combining polyolefin base layer with a coating layer containing ceramic particles (such as alumina, boehmite) and binder. This composite structure maintains the insulation properties of polyolefin while adding high-temperature stability through the ceramic component that prevents shrinkage at elevated temperatures.
Solution Approach 2:
The separator employs a porous structure with controlled pore size and distribution, allowing electrolyte penetration while maintaining mechanical integrity. The porous ceramic coating layer provides thermal stability and prevents electrode contact even when the polyolefin base shrinks at high temperatures.
2Reliability
If flame retardant electrolyte is used to prevent ignition, then safety is improved, but impregnation into separator deteriorates due to poor wettability
Solution Approach 1:
The surface properties of the separator are modified by changing the chemical composition of the coating layer, incorporating hydrophilic ceramic particles and binder materials that alter surface energy. This parameter change enables flame retardant electrolyte to wet and penetrate the separator effectively while maintaining the flame retardant properties of the electrolyte.
3Reliability
If flame retardant electrolyte is used to prevent ignition, then safety is improved, but ionic conductivity deteriorates due to high interfacial resistance
Solution Approach 1:
The coating layer is designed as a composite with conductive ceramic particles (such as alumina, boehmite) and binder materials that create continuous pathways for ion transport. This composite structure reduces interfacial resistance between electrolyte and separator, maintaining high ionic conductivity while preserving flame retardancy.
Solution Approach 2:
The porous structure of the coating layer with optimized pore size and connectivity allows efficient ion transport through the separator. The interconnected pore network reduces tortuosity and interfacial resistance, enabling high ionic conductivity despite the presence of flame retardant electrolyte.
4Ease of manufacture
If electrolyte is not well impregnated into separator, then manufacturing is simplified, but battery performance deteriorates due to non-uniform reactions and dendrite formation
Solution Approach 1:
The coating layer parameters (composition, thickness, pore size) are optimized to achieve spontaneous and uniform electrolyte impregnation. The hydrophilic ceramic particles and binder create capillary forces that drive uniform electrolyte distribution throughout the separator, preventing localized non-uniform reactions and dendrite formation.
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 high-temperature safety, electrolyte impregnation, and battery performance by preventing ignition and ensuring uniform reactions, thereby enhancing capacity, output, and life characteristics of lithium secondary batteries.
Implementation Method 1
the coating layer includes a first coating layer that comes into opposing contact with the negative electrode and a second coating layer that does not come into opposing contact with the negative electrode, the first coating layer includes any one particle selected from i) to iii), the second coating layer includes iii) when i) or ii) is included in the first coating layer, and includes either i) or ii) when iii) is included in the first coating layer, wherein: i) oxide-based solid electrolyte particles, and ceramic particles having an absolute value of zeta potential of 25 mV or more
Data Source
AI summary
An electrode assembly includes: a positive electrode, a negative electrode, and a coating layer located between the positive electrode and the negative electrode; wherein the coating is formed in two or more layers in the stacking direction of the positive electrode and the negative electrode; wherein the coating layer includes a first coating layer that comes into opposing contact with the negative electrode and a second coating layer that does not come into opposing contact with the negative electrode, the first coating layer includes any one particle selected from i) to iii), the second coating layer includes iii) when i) or ii) is included in the first coating layer, and includes either i) or ii) when iii) is included in the first coating layer, wherein i) oxide-based solid electrolyte particles and ceramic particles having an absolute value of zeta potential of 25 mV or more, ii) oxide-based solid electrolyte particles, and iii) ceramic particles with an absolute value of zeta potential of 25 mV or more.