Polyvinyl Phosphonate Solid Electrolyte for Safe Lithium Batteries
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Solution Overview
Problem
Conventional electrolytes for lithium batteries pose safety concerns due to thermal runaway and explosion risks, and existing solid-state electrolytes suffer from low conductivity, high interfacial impedance, and poor mechanical properties, limiting their widespread adoption in lithium-ion and lithium metal batteries.
Innovation Solution
A quasi-solid or solid-state electrolyte system comprising a polyvinyl phosphonate polymer with a lithium salt and a non-aqueous liquid solvent, which is highly flame-resistant and compatible with existing battery production facilities, featuring a phosphorus-containing polymer functionalized at the side chain and a lithium salt dispersed within, to enhance lithium ion conductivity and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic liquid electrolytes are used, then high lithium ion conductivity is achieved, but thermal runaway and explosion risks occur
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to solid by using polyvinyl phosphonate polymer, thereby eliminating the thermal runaway and explosion risks associated with conventional liquid electrolytes while maintaining lithium ion conductivity
Solution Approach 2:
The patent creates a composite electrolyte system combining polyvinyl phosphonate polymer matrix with lithium salt (LiClO4, LiBF4, LiPF6, or LiTFSI), forming a solid-state composite that provides both safety and ionic conductivity
2Reliability
If inorganic solid-state electrolytes are used, then high conductivity is achieved, but interfacial impedance with electrodes increases
Solution Approach 1:
The patent modifies the interface properties by using a polymer-based solid electrolyte that can form better contact with electrodes compared to rigid inorganic solids, reducing interfacial impedance while maintaining solid-state safety benefits
Solution Approach 2:
The polyvinyl phosphonate polymer structure provides local flexibility and adaptability at the electrode-electrolyte interface, improving contact quality and reducing interfacial resistance compared to brittle inorganic solids
3Reliability
If inorganic ceramic electrolytes are used, then high conductivity is achieved, but mechanical brittleness and poor film-forming ability worsen
Solution Approach 1:
The patent develops a composite solid electrolyte where the polyvinyl phosphonate polymer provides mechanical flexibility and film-forming ability while the lithium salt ensures high ionic conductivity, combining the benefits of both organic and inorganic materials
Solution Approach 2:
The patent changes the mechanical properties parameter by using a polymer matrix instead of ceramic, transforming the electrolyte from brittle to flexible while maintaining solid-state characteristics and ionic conductivity
4Reliability
If ionic liquids are used, then non-flammability is achieved, but viscosity increases reducing lithium ion transport
Solution Approach 1:
The patent changes the viscosity parameter by using a polymer solid electrolyte structure that provides channels for lithium ion transport, achieving fire resistance without the high viscosity penalty of ionic liquids
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 electrolyte system significantly reduces the risk of fire and explosion, improves lithium ion conductivity, and is compatible with existing battery production processes, making it suitable for high-performance and safe lithium batteries.
Implementation Method 1
a polyvinyl phosphonate polymer comprising chains derived from a phosphonate vinyl monomer and a lithium salt dissolved or dispersed in the polymer
Data Source
AI summary
A rechargeable lithium battery comprising an anode, a cathode, and a quasi-solid or solid-state electrolyte in ionic communication with the anode and the cathode, wherein the electrolyte comprises a polymer comprising chains derived from a phosphonate vinyl monomer and a lithium salt dissolved or dispersed in the polymer, wherein the lithium salt occupies a weight fraction from 0.1% to 50% based on the total weight of the lithium salt and the polyvinyl phosphonate combined. The polymer may further comprise a flame-retardant and/or particles of an inorganic solid-state electrolyte. Also provided is an electrolyte composition comprising a lithium salt and an initiator and/or a crosslinking agent dissolved or dispersed in a reactive liquid medium comprising a reactive monomer or oligomer that is a precursor to a vinyl phosphonate polymer.