Lithium Anode Protective Film for Dendrite Inhibition
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Solution Overview
Problem
Lithium dendrites form on the surface of lithium anodes during charging and discharging, leading to reduced cycle characteristics and potential short circuits in lithium-ion batteries, as existing technologies lack effective means to inhibit their growth.
Innovation Solution
A protective film comprising a polymeric porous film with a layer of polymeric material having lithium-ion conductivity is applied to the anode, ensuring uniform diffusion of lithium ions and preventing uncontrolled precipitation, thereby inhibiting dendrite growth. The film is made of materials like tetrafluoroethylene polymers or copolymers, which are impregnated with a lithium-ion conductive material to enhance stability and prevent defluorination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous polymer film separator is used to prevent direct electrical contact between electrodes, then electrical isolation is achieved, but lithium dendrites can grow through the separator causing short circuits
Solution Approach 1:
A protective film comprising a porous polymer film and a lithium-ion conductive polymer layer is introduced as an intermediary between the lithium anode and the separator. This protective film acts as a mediator that allows lithium ion transport while physically blocking dendrite growth, thereby resolving the contradiction between maintaining electrical isolation and preventing dendrite-induced short circuits
Solution Approach 2:
The protective film is constructed as a composite material system combining a porous polymer film (providing structural support and ion transport pathways) with a lithium-ion conductive polymer layer (providing dendrite resistance and uniform ion distribution). This composite structure simultaneously achieves electrical isolation, dendrite prevention, and maintained ionic conductivity
2Object-affected harmful factors
If carbonaceous materials or metal alloys are used as negative electrode to inhibit lithium dendrite growth, then dendrite formation is reduced, but battery capacity is reduced
Solution Approach 1:
The negative electrode system is segmented into two functional components: a lithium metal anode (providing high capacity) and a protective film (providing dendrite resistance). This segmentation allows each component to perform its specialized function optimally, resolving the contradiction between achieving high capacity and preventing dendrites by maintaining lithium metal's high capacity while using the protective film's dendrite-blocking capability
Solution Approach 2:
The protective film serves as an intermediary layer between the lithium metal anode and the electrolyte/separator, enabling the use of high-capacity lithium metal without suffering from dendrite formation. The film mediates the interaction between lithium ions and the lithium metal surface, ensuring uniform deposition while maintaining the high capacity benefits of lithium metal
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 effectively inhibits the growth of lithium dendrites, improving the cycle life and safety of lithium-ion batteries by ensuring uniform ion diffusion and maintaining the structural integrity of the anode, preventing short circuits and maintaining battery performance.
Implementation Method 1
a polymeric material not containing a lithium electrolyte salt but having lithium-ion conductivity per se
Implementation Method 2
ensuring uniform diffusion of lithium ions and preventing uncontrolled precipitation
Implementation Method 3
a polymeric porous film... wherein the polymeric porous film is completely impregnated with the polymeric material
Data Source
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AI summary
An object of the present invention is to provide an anode protective film that is more certainly able to inhibit the growth of dendrites that can be formed on an anode, and a separator and a secondary battery using the same. A protective film for protecting an anode including lithium, including a polymeric porous film and a polymeric material having lithium-ion conductivity per se, wherein at least one surface of the polymeric porous film is covered with the polymeric material having lithium-ion conductivity.