Conducting Polymer Network Anode Layer for Lithium Metal Batteries
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Solution Overview
Problem
Lithium metal batteries face challenges with dendrite formation and reactions between lithium metal and electrolytes, leading to internal short circuits and thermal runaway, which hinder their commercialization due to complexity, cost, and low lithium ion conductivity in existing solutions.
Innovation Solution
A lithium metal secondary battery design featuring an anode with a conductive polymer network layer that provides ionic and electronic conductivity, supporting lithium ion transport and preventing dendrite formation, combined with a lithium alloy anode active material and a porous separator or solid-state electrolyte for improved stability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective surface layer is applied to the lithium metal anode to prevent dendrite formation, then safety and cycle stability are improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The anode is segmented into multiple functional layers: a lithium metal layer and a conducting polymer network-based protective layer. This segmentation allows each layer to perform its specific function - the lithium metal provides high capacity while the polymer network prevents dendrite formation and stabilizes the interface, resolving the contradiction between maintaining simple structure and improving reliability.
Solution Approach 2:
The invention uses a composite anode structure combining lithium metal with a conducting polymer network (such as polyacetylene, polythiophene, or polypyrrole). This composite material approach integrates the high capacity of lithium metal with the protective and conductive properties of the polymer network, achieving both improved reliability and controlled complexity through a well-defined two-layer composite structure.
2Reliability
If a multilayer anode structure with multiple protective layers is used to prevent dendrites, then reliability is improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The invention extracts and eliminates unnecessary intermediate layers from complex multilayer structures, retaining only the essential lithium metal layer and the conducting polymer protective layer. This simplification maintains dendrite prevention functionality while dramatically reducing manufacturing complexity and cost compared to structures with multiple glass, polymer, and metal layers.
Solution Approach 2:
The conducting polymer network is applied locally at the critical lithium metal-electrolyte interface where dendrite formation occurs. This localized protection approach focuses the protective function exactly where needed, eliminating the need for extensive multilayer structures and reducing manufacturing complexity while maintaining high reliability.
3Reliability
If solid polymer electrolyte layers are used to stabilize the lithium anode, then safety is improved, but lithium ion conductivity decreases
Solution Approach 1:
The invention changes the key parameter of ionic conductivity by using a conducting polymer network with conjugated double bonds and delocalized electrons, which provides both electronic conductivity and ionic conductivity. This parameter change allows the protective layer to maintain high lithium ion conductivity while providing the stability and safety benefits of a solid polymer structure.
Solution Approach 2:
The conducting polymer network is combined with lithium salts (such as LiClO4, LiBF4, or LiPF6) to create a composite material that exhibits both structural stability and high ionic conductivity. This composite approach resolves the contradiction by integrating the stabilizing function of solid polymers with the high ionic conductivity needed for battery performance.
4Reliability
If conventional protective coatings are applied to the lithium anode, then dendrite formation is reduced, but the battery energy density decreases due to added complexity and weight
Solution Approach 1:
The conducting polymer network forms a thin, flexible protective film on the lithium metal anode. This thin-film approach provides dendrite resistance and interface stabilization while adding minimal weight and volume, preserving the high energy density of the lithium metal battery system.
Solution Approach 2:
The conducting polymer network is a relatively simple, cost-effective material that can be applied as a thin coating, replacing complex and expensive multilayer protective structures. This approach provides the necessary protection against dendrites while minimizing the added weight and cost, making the battery more commercially viable.
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 prevents dendrite formation, ensures uniform lithium ion deposition, reduces dead lithium, and enhances cycle stability and energy density, addressing the safety and efficiency concerns of lithium metal batteries.
Implementation Method 1
anode-protecting layer... comprising an electrically and ionically conducting network of cross-linked polymer chains having a lithium ion conductivity from 10−8 to 5×10−2 S/cm
Implementation Method 2
anode-protecting layer... comprising an electrically and ionically conducting network of cross-linked polymer chains having an electron conductivity from 10−8 to 103 S/cm
Implementation Method 3
anode-protecting layer... comprising an electrically and ionically conducting network of cross-linked polymer chains
Implementation Method 4
anode active material layer containing a layer of lithium or lithium alloy
Data Source
AI summary
Provided is a lithium metal secondary battery comprising a cathode, an anode, an electrolyte-separator assembly disposed between the cathode and the anode, wherein the anode comprises: (a) an anode active material layer containing a layer of lithium or lithium alloy optionally supported by an anode current collector; and (b) an anode-protecting layer in physical contact with the anode active material layer and in ionic contact with the electrolyte-separator assembly, having a thickness from 10 nm to 500 μm and comprising an electrically and ionically conducting network of cross-linked conjugated polymer chains having a lithium ion conductivity from 10−8 to 5×10−2 S/cm and an electron conductivity from 10−8 to 103 S/cm.