Mixed-Conducting Anode Coatings for SEI and Dendrite Suppression
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Solution Overview
Problem
Current Li-ion batteries face challenges with lithium and silicon anodes due to volumetric change during cycling, formation of an inefficient solid electrolyte interphase (SEI) layer, and the risk of dendrite formation leading to thermal runaway, which limits energy density and safety.
Innovation Solution
The implementation of protective films, such as lithium transition metal dichalcogenides and lithiated lithium-titanium-oxides (LTO), on lithium or graphite-containing anodes to provide stable, mixed conduction layers that suppress dendrite growth and enhance ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid ceramic layer is used to prevent dendrite growth and SEI formation, then anode stability is improved, but cell resistance increases
Solution Approach 1:
The patent applies composite materials by combining a rigid ceramic layer (such as Al2O3, Li2SiO3, or Li4SiO4) with a conductive polymer layer (such as polyaniline, polythiophene, or polypyrrole) to form a multi-layer protective coating on the anode. This composite structure resolves the contradiction by providing both the mechanical stability and dendrite prevention from the ceramic layer and the electrical conductivity from the polymer layer, thereby maintaining low cell resistance while ensuring anode stability.
2Loss of energy
If an electronic conducting layer is used to promote electronic conductivity, then cell resistance is reduced, but dendrite protection is insufficient
Solution Approach 1:
The patent uses composite materials by layering a conductive polymer (providing electronic conductivity) over a rigid ceramic base layer (providing mechanical strength and dendrite prevention). This composite approach allows the polymer to reduce cell resistance through its electronic conducting properties while the underlying ceramic structure continues to provide physical barriers against dendrite growth, thus simultaneously addressing both requirements.
Solution Approach 2:
The protective coating is segmented into multiple functional layers: a rigid ceramic layer for mechanical stability and dendrite prevention, and a conductive polymer layer for electronic conductivity. This segmentation allows each layer to specialize in its primary function without compromising the other, resolving the contradiction between resistance reduction and dendrite protection.
3Quantity of substance
If lithium metal anode is used to increase specific capacity, then energy density is improved, but SEI formation and dendrite risk increase
Solution Approach 1:
The patent applies composite materials by coating the lithium metal anode with a multi-layer structure consisting of a rigid ceramic layer and a conductive polymer layer. The ceramic layer prevents direct contact between lithium and electrolyte, suppressing SEI formation and dendrite growth, while the polymer layer maintains electronic conductivity. This composite protective coating enables lithium metal anodes to achieve their high specific capacity (3860 mAh/g) while significantly improving safety and stability.
4Reliability
If graphite anode is used to ensure stability, then safety is improved, but specific capacity is limited
Solution Approach 1:
The patent applies parameter changes by transitioning from graphite anode (specific capacity 372 mAh/g) to lithium metal anode (specific capacity 3860 mAh/g), thereby increasing the quantity of lithium storage capacity by more than 10 times. The rigid ceramic protective coating is introduced to maintain stability and prevent safety issues, enabling the system to achieve high energy density while maintaining reliability through the protective barrier that prevents SEI formation and dendrite growth.
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 protective films improve anode stability, reduce impedance, and enhance energy density by preventing SEI inefficiencies and dendrite formation, thereby increasing the safety and performance of Li-ion batteries.
Implementation Method 1
forming a protective film stack on the lithium metal film... the first protective film comprises Li9Ti5O12... providing stable, mixed conduction layers that suppress dendrite growth and enhance ion conductivity
Implementation Method 2
a rigid ceramic layer, which is ion conducting, is used to prevent the growth of dendrites and possible formation of SEI
Data Source
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AI summary
Interfacial films, which are both electronic conducting and ion conducting, for anode films are provided. The one or more protective films described herein may be mixed conduction materials, which are both electronic conducting and ion-conducting. The one or more protective films described herein may include materials selected from lithium transition metal dichalcogenides, Li9Ti5O12, or a combination thereof. The lithium transition metal dichalcogenide includes a transition metal dichalcogenide having the formula MX2, wherein M is selected from Ti, Mo, or W and X is selected from S, Se, or Te. The transition metal dichalcogenide may be selected from TiS2, MoS2, WS2, or a combination thereof. The lithium transition metal dichalcogenide may be selected from lithium-titanium-disulfide (e.g., LiTiS2), lithium-tungsten-disulfide (e.g., LiWS2), lithium-molybdenum-disulfide (e.g., LiMoS2), or a combination thereof.