Hybrid Battery Separator for Dendrite-Resistant Lithium Metal Cells
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Solution Overview
Problem
Rechargeable lithium metal batteries face challenges due to lithium metal dendrite formation leading to internal short circuits and thermal runaway, and detrimental reactions between lithium metal and the electrolyte, which hinder their commercialization, especially in electric vehicles and microelectronic devices. Additionally, conventional solid electrolytes have low lithium ion conductivity and poor contact with lithium metal, reducing battery efficiency and stability.
Innovation Solution
A polymer hybrid separator comprising thermally stable polymers with intersecting fibers and lithium salts or inorganic particles, which acts as both a separator and anode protection layer, enhancing lithium ion conductivity and preventing dendrite formation while maintaining good contact with the anode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as anode active material to achieve high capacity and energy density, then energy density is improved, but dendrite formation occurs leading to internal short circuits and thermal runaway
Solution Approach 1:
A protective surface layer comprising a mixture of polynuclear aromatic compounds and polyethylene oxide is applied to the lithium metal anode. This intermediary layer acts as a mediator between the lithium metal and the electrolyte, enabling uniform lithium ion transfer while preventing dendrite formation and eliminating the need for excessive lithium metal
Solution Approach 2:
The protective surface layer is composed of a composite material mixture of polynuclear aromatic compounds and polyethylene oxide. This composite structure combines the ion-conducting properties of polyethylene oxide with the stabilizing effects of polynuclear aromatic compounds to prevent dendrite formation while maintaining high lithium ion conductivity
2Reliability
If multiple protective layers are applied to the anode to prevent dendrites, then dendrite prevention is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The protective surface layer combines multiple functions (ion conduction, dendrite prevention, and interface stabilization) into a single layer, eliminating the need for complex multilayer structures while maintaining effective dendrite prevention
Solution Approach 2:
The protective surface layer performs multiple functions simultaneously: it acts as an ion-conducting pathway, a dendrite-prevention barrier, and an interface-stabilizing layer, making the anode structure simpler while maintaining reliability
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 polymer hybrid separator significantly improves cycle stability, prevents dendrite penetration, ensures uniform lithium deposition, and maintains minimal interfacial resistance, thereby enhancing the safety and energy density of lithium metal batteries.
Implementation Method 1
the first thermally stable polymer, the second thermally stable polymer, or both the first and the second thermally stable polymer are selected from the group consisting of polyimide, poly(amic acid), poly(amide imide), poly(ether imide), aromatic polyamide, polysulfone, polyether sulfone
Implementation Method 2
a polymer hybrid separator comprising thermally stable polymers with intersecting fibers
Implementation Method 3
prevents dendrite penetration, ensures uniform lithium deposition
Data Source
AI summary
Provided is a polymer hybrid separator for use in a battery, the separator comprising multiple fibers of a first thermally stable polymer (first fibers) and multiple fibers of a second thermally stable polymer (second fibers), which are different in chemical composition or diameter than the first fibers, wherein the first fibers intersect with the second fibers and are bonded by the second fibers at the points of intersection. The thermally stable polymer fibers preferably have a melting point or thermal decomposition temperature higher than 250° C. (preferably >300° C., further preferably >400° C., still further preferably >500° C., and most preferably >600° C.). Also provided are a process for producing such a separator and a lithium or sodium secondary battery comprising a cathode, an anode, such a separator disposed between the cathode and the anode, and an electrolyte.