Alternating Graphene Oxide Boron Nitride Separator for Lithium-Sulfur Batteries
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Solution Overview
Problem
Lithium-sulfur batteries face issues with lithium polysulfides causing capacity loss and lithium dendrites leading to instability, safety concerns, and reduced lifespan due to the formation of lithium polysulfides and dendrites during charging and discharging.
Innovation Solution
A separator with a multi-layered coating layer composed of alternately laminated graphene oxide and boron nitride layers is used, which effectively adsorbs lithium polysulfides and inhibits the growth of lithium dendrites, enhancing the battery's capacity and stability by facilitating ion transfer while maintaining high sulfur loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective film is formed on the electrode to prevent lithium dendrite growth, then safety is improved, but the protective film acts as a resistive layer that lengthens or blocks the lithium ion path, reducing battery performance
Solution Approach 1:
The separator uses a porous structure with controlled pore size and distribution that allows lithium ions to pass through efficiently while providing physical barriers to dendrite growth. The porous architecture maintains ion conductivity pathways without requiring additional protective films that would block ion transport.
Solution Approach 2:
The separator combines multiple materials with complementary properties: a base separator material providing structural support and ion conductivity, combined with functional coatings or composite structures that enhance dendrite resistance while maintaining porosity for ion transport. This composite approach achieves both safety and performance.
2Loss of substance
If metal chalcogenide or alumina is added to delay sulfur leakage, then positive electrode active material retention is improved, but sulfur is lost during processing and the method is complicated, limiting the amount of active material that can be loaded
Solution Approach 1:
Instead of uniformly distributing sulfur-retention additives throughout the entire electrode, the invention applies functional materials locally at specific interfaces where sulfur leakage occurs most, such as coating the separator surface or creating localized functional layers. This reduces processing complexity and sulfur loss while maintaining effective retention.
Solution Approach 2:
The separator acts as an intermediary layer between the positive and negative electrodes, incorporating functional materials that specifically address sulfur leakage at the interface. This mediator approach prevents sulfur loss without requiring complex processing of the entire electrode structure, enabling higher sulfur loading.
3Loss of substance
If the separator structure is enhanced to prevent lithium polysulfide diffusion, then capacity retention is improved, but ion transfer resistance increases, reducing charging/discharging efficiency
Solution Approach 1:
The separator is divided into multiple functional layers, each with specific properties: one layer provides polysulfide barrier functionality while another layer maintains high ion conductivity. This segmented structure allows simultaneous achievement of capacity retention and fast ion transport without compromising either function.
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 the charging and discharging efficiency, extends the battery's life, and prevents short-circuiting, heat generation, and explosion risks, resulting in a more stable and high-capacity lithium-sulfur battery.
Implementation Method 1
a multi-layered coating layer formed by alternately laminating a graphene oxide layer and a boron nitride layer
Implementation Method 2
the multi-layered coating layer is formed by alternately laminating a graphene oxide layer and a boron nitride layer
Implementation Method 3
the separator comprises a porous substrate and a multi-layered coating layer formed on at least one side of the porous substrate
Data Source
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AI summary
The present invention relates to a separator capable of simultaneously solving the problems caused by the lithium polysulfides and lithium dendrites generated in a conventional lithium-sulfur battery wherein the separator includes a porous substrate alternately laminated with a graphene oxide layer and a boron nitride layer on its at least one side, and to a lithium-sulfur battery comprising the same.