Ceramic-Graphene Oxide Separator Coating for Low-Resistance Adhesion
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Solution Overview
Problem
Lithium-ion batteries face issues with poor wettability of polyolefin films by electrolyte solutions, leading to safety risks due to lithium dendrite formation and high resistance caused by excessive binder use to enhance adhesion of ceramic coatings.
Innovation Solution
A three-layer composite separator structure with ceramic particles, graphene oxide, and a binder, where the mass ratios of ceramic particles to binder and the sum of ceramic particles and binder to graphene oxide are optimized to improve adhesion, wettability, and ionic conductivity, reducing resistance and preventing lithium dendrite piercing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating containing ceramic particles is applied on the separator to promote electrolyte solution wettability and prevent lithium dendrite piercing, then safety and wettability are improved, but powder shedding occurs due to poor adhesion between ceramic particles and polyolefin films
Solution Approach 1:
The patent uses a binder as an intermediary substance between the ceramic particles and the polyolefin film. The binder contains functional groups that can chemically or physically bond to both the ceramic particles and the polyolefin, creating strong adhesion and preventing powder shedding while maintaining the safety and wettability benefits of the ceramic coating
Solution Approach 2:
The patent creates a composite coating structure consisting of ceramic particles, binder, and optionally graphene oxide or conductive polymer. This composite material combines the wettability-enhancing properties of ceramic particles with the adhesion-providing properties of the binder and the conductivity-enhancing properties of graphene oxide or conductive polymer, achieving multiple functions simultaneously
2Stability of the object's composition
If a large amount of binder is introduced to increase adhesion force between ceramic particles and polyolefin films and reduce powder shedding, then adhesion is improved, but resistance of the separator increases and kinetic performance deteriorates
Solution Approach 1:
The patent optimizes the mass ratio of binder to ceramic particles within a specific range (0.1-5 wt%), finding the optimal balance between adhesion and resistance. Additionally, the patent introduces graphene oxide or conductive polymer to enhance conductivity, allowing for reduced binder content while maintaining both adhesion and low resistance
Solution Approach 2:
The patent introduces graphene oxide or conductive polymer as an intermediary conductive phase between the binder and ceramic particles. This intermediary component provides additional conductive pathways, reducing the overall resistance of the coating while the binder maintains adhesion, thus decoupling the trade-off between adhesion and resistance
3Strength
If polyolefin films are used as separators, then mechanical properties are maintained, but wettability with electrolyte solution is poor
Solution Approach 1:
The patent creates a composite structure by coating polyolefin films with a mixture of ceramic particles and binder. The polyolefin film provides the mechanical strength and separation function, while the ceramic particle coating provides hydrophilicity and improved electrolyte wettability, achieving both mechanical integrity and enhanced wettability
Solution Approach 2:
The patent modifies only the surface of the polyolefin film through coating, leaving the bulk mechanical properties unchanged. The coating layer provides localized hydrophilic properties for improved wettability, while the underlying polyolefin maintains its mechanical strength and separation functionality
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 separator achieves improved safety, dynamic, and cycling performance by enhancing electrolyte solution wettability, mechanical strength, and ionic conductivity, while minimizing resistance and preventing lithium dendrite-induced safety hazards.
Implementation Method 1
the wettability between the polyolefin films and the electrolyte solution is poor
Implementation Method 2
allow ions to pass through freely
Implementation Method 3
the lithium dendrites generated during battery use may pierce the separator and cause short circuit
Implementation Method 4
it is necessary to introduce a binder to increase a adhesion force between the ceramic particles and the polyolefin films
Implementation Method 5
A first aspect of the present application provides a separator, including first base films sequentially arranged in a stacked manner; a second base film; and a coating containing ceramic particles, graphene oxide and a binder
Data Source
AI summary
The present application provides a separator, including first base films sequentially arranged in a stacked manner, a coating containing ceramic particles, graphene oxide and a binder, and a second base film. The separator in the present application has good electrolyte solution wettability, may effectively inhibit the growth of lithium dendrites, and has a small resistance, which may effectively improve the safety, dynamic and cycling performance of a corresponding battery. The present application further provides a secondary battery, battery module, battery pack and electrical apparatus using the separator.