Sulfonated Elastomer Anode Layer for Lithium Dendrite Suppression
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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, as well as detrimental reactions between lithium metal and the electrolyte, which result in capacity decay and safety concerns.
Innovation Solution
A lithium metal secondary battery is developed with a cathode, an anode, and an electrolyte or separator-electrolyte assembly, where the anode comprises a layer of lithium or lithium alloy and a thin anode-protecting layer made of a conductive sulfonated elastomer composite. This composite has a specific composition and properties that prevent dendrite formation and maintain a stable lithium ion interface.
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 safety issues and short cycle life
Solution Approach 1:
A thin protective layer comprising a conductive sulfonated elastomer composite is introduced as an intermediary between the lithium metal anode and the electrolyte. This protective layer mediates the interaction by preventing direct contact between lithium metal and electrolyte, thereby eliminating dendrite formation and detrimental reactions while maintaining high ionic conductivity for lithium ion transport.
Solution Approach 2:
The protective layer is constructed as a composite material consisting of a sulfonated elastomer matrix combined with conductive reinforcement materials. This composite structure provides both the mechanical flexibility needed to accommodate lithium volume changes and the electrical conductivity necessary to prevent electron transfer that would cause dendrite formation, while simultaneously maintaining high lithium ion conductivity.
2Quantity of substance
If lithium metal anode is used to achieve high capacity, then capacity is improved, but detrimental reactions with electrolyte cause capacity decay
Solution Approach 1:
The conductive sulfonated elastomer composite protective layer serves as a stable intermediary barrier between lithium metal and electrolyte. It prevents direct detrimental reactions between lithium metal and electrolyte that cause capacity decay, while its high lithium ion conductivity ensures efficient ion transport is maintained, preserving the lithium capacity over extended cycling.
3Reliability
If protective layers are applied to prevent dendrite formation, then safety is improved, but device complexity increases
Solution Approach 1:
The protective layer is designed as a thin film with thickness from 1 nm to 100 μm, making it sufficiently thin to minimize added complexity and resistance while still providing effective dendrite prevention. The sulfonated elastomer composite provides flexible mechanical properties that allow the thin film to accommodate lithium volume changes during cycling without cracking or delaminating.
Solution Approach 2:
The composite nature of the protective layer combines multiple functions in a single material system: the sulfonated elastomer provides mechanical flexibility and ion conductivity, while the conductive reinforcement materials provide electron conductivity to prevent dendrite formation. This multi-functional composite approach achieves safety without requiring multiple separate layers or complex structures.
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 implementation of the sulfonated elastomer composite anode-protecting layer effectively prevents lithium metal dendrite formation, ensures uniform lithium ion deposition, and reduces detrimental reactions with the electrolyte, thereby enhancing the safety, cycle stability, and energy density of lithium metal batteries.
Implementation Method 1
ensures uniform lithium ion deposition
Implementation Method 2
effectively prevents lithium metal dendrite formation
Implementation Method 3
reduces detrimental reactions with the electrolyte
Data Source
AI summary
The invention provides a method of improving the cycle-life of a lithium metal secondary battery. The method comprises implementing an anode-protecting layer between an anode active material layer and a porous separator/electrolyte, wherein the anode-protecting layer or cathode-protecting layer comprises a conductive sulfonated elastomer composite having from 0.01% to 50% by weight of a conductive reinforcement material dispersed in a sulfonated elastomeric matrix material and the protecting layer has a thickness from 1 nm to 100 μm, a fully recoverable tensile strain from 2% to 500%, a lithium ion conductivity from 10−7 S/cm to 5×10−2 S/cm, and an electrical conductivity from 10−7 S/cm to 100 S/cm when measured at room temperature.