Composite Separator Reduces Flammable Electrolyte in Li-Ion Batteries
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Solution Overview
Problem
Lithium-ion batteries face safety concerns due to the risk of explosion and toxic gas release when the casing is damaged, primarily because of the flammability and toxicity of the liquid electrolyte and the formation of hydrogen fluoride from the lithium salt.
Innovation Solution
A composite separator is developed, comprising a polymer membrane, a binder, and a solid inorganic lithium-ion conductor with a higher volume and weight fraction than the liquid electrolyte, which reduces the amount of liquid electrolyte and conducting salt, thereby minimizing the risk of ignition and toxic gas production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolyte and conducting salt are used in lithium-ion batteries, then ionic conductivity and battery performance are improved, but safety deteriorates due to flammability and toxic gas release
Solution Approach 1:
The patent changes the physical state of the electrolyte from liquid to solid by incorporating inorganic solid electrolyte particles (such as Li1.3Al0.3Phosphorus0.3O2.7) into the separator. This parameter change eliminates the flammability and toxic gas release associated with liquid electrolytes while maintaining ionic conductivity through the solid inorganic material.
Solution Approach 2:
The patent creates a composite separator structure combining organic polymer matrix (providing mechanical strength and flexibility) with inorganic solid electrolyte particles (providing ionic conductivity and safety). This composite approach allows the separator to maintain its functional properties while eliminating the harmful effects of pure liquid electrolyte systems.
2Reliability
If the amount of liquid electrolyte is reduced, then safety is improved, but ionic conductivity may deteriorate
Solution Approach 1:
The patent replaces liquid electrolyte with solid inorganic electrolyte particles having high ionic conductivity. The solid particles are distributed throughout the separator matrix, creating conductive pathways that maintain or improve ionic transport while eliminating the need for large amounts of liquid electrolyte.
Solution Approach 2:
The solid inorganic electrolyte particles act as intermediaries for ion transport between the electrodes. These particles provide alternative conduction pathways that do not rely on liquid electrolyte, thereby maintaining ionic conductivity while reducing or eliminating liquid electrolyte content for improved safety.
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 composite separator significantly reduces the risk of ignition and health hazards by lowering the amount of flammable solvents and toxic lithium hexafluorophosphate, enhancing safety in lithium-ion batteries, especially in applications like motor vehicles.
Implementation Method 1
a solid inorganic lithium-ion conductor, wherein the solid inorganic lithium-ion conductor is present in a higher volume fraction and weight fraction than the liquid electrolyte
Implementation Method 2
The composite separator of the invention has a porous structure
Data Source
AI summary
A composite separator is provided which includes a polymer membrane, a binder, a solid inorganic lithium-ion conductor and a liquid electrolyte. The solid inorganic lithium-ion conductor is present in the composite separator in a higher volume and weight proportion than the liquid electrolyte. A method for forming the composite separator is also provided, and a lithium-ion battery is provided which includes a composite separator having a polymer membrane, a binder, a solid inorganic lithium-ion conductor and a liquid electrolyte.