Lithium-Ion Mixed Conduction Membrane Blocks Polysulfide Shuttle
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Solution Overview
Problem
Lithium-sulfur batteries face limitations due to the polysulfide shuttle, which leads to self-discharge, reduced cycle life, and decreased power output, as soluble polysulfides diffuse between electrodes, causing irreversible capacity loss and passivation of the lithium electrode.
Innovation Solution
A non-porous lithium-ion mixed conduction membrane is introduced, which is impermeable to polysulfide ions while allowing lithium ion conductivity, using partially lithiated materials like lithiated cobalt oxide, to prevent polysulfide species from reaching the anode and undergoing irreversible precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium nitrate is used as an additive to form a passivation film on the lithium metal surface, then the polysulfide shuttle is prevented, but the lithium nitrate is consumed at each cycle making the effect temporary
Solution Approach 1:
A lithium ion conductive membrane is introduced as an intermediary component between the positive and negative electrodes. This membrane selectively blocks polysulfide species while allowing lithium ion transport, preventing the polysulfide shuttle without being consumed during cycling, thus providing long-term stable protection.
Solution Approach 2:
The passivation function is extracted from the lithium metal surface (where it was previously achieved by lithium nitrate) and transferred to a dedicated lithium ion conductive membrane component. This separation allows the membrane to perform the blocking function continuously without consuming the lithium metal or requiring replenishment.
2Reliability
If solid electrolytes are used to inhibit the polysulfide shuttle, then the shuttle is effectively prevented, but the rate capability is reduced
Solution Approach 1:
The membrane exhibits different properties for different species: it is impermeable to polysulfide ions (blocking function) but highly conductive to lithium ions (transport function). This local quality differentiation allows simultaneous achievement of shuttle prevention and high rate capability.
Solution Approach 2:
The lithium ion conductive membrane is composed of a composite structure containing lithium ion conductive material (such as lithium phosphorus oxynitride or lithium lanthanum zirconium oxide) dispersed in a polymeric binder, combining the benefits of solid electrolyte (shuttle blocking) with good ionic conductivity (high rate capability).
3Reliability
If barrier layers are used to slow polysulfide diffusion, then the polysulfide shuttle is reduced at higher cycling rates, but the self-discharge and capacity loss still occur at slower cycling rates
Solution Approach 1:
Unlike consumable lithium nitrate additive, the lithium ion conductive membrane is a durable, non-consumable component that maintains its blocking function throughout the battery's operational life, providing consistent protection across all cycling conditions without degradation or depletion.
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 membrane effectively suppresses nearly 85% of the polysulfide shuttle reaction, significantly improving cycle life and maintaining high discharge-to-charge efficiency, comparable to lithium nitrate additives, while preventing lithium dendrite formation.
Implementation Method 1
the lithium ion conductive material having lithium ion conductivity and electrical conductivity
Implementation Method 2
a lithium ion conductive material with lithium ion conductivity and electrical conductivity dispersed within the polymeric binder
Implementation Method 3
the ability of the material to transport electrons and lithium ions
Implementation Method 4
In the present case we use this term to describe the ability of the material to transport electrons and lithium ions
Implementation Method 5
The lithium ion mixed conduction membrane prevents polysulfide species reaching the anode
Data Source
AI summary
A lithium ion mixed conduction membrane includes an optional polymeric binder and a partially lithiated ion conductive material having lithium ion conductivity and electrical conductivity dispersed within the polymeric binder that is capable of improving the performance and cycle life of lithium-sulfur rechargeable batteries and other batteries exhibiting the polysulfide shuttle. One or more lithium ion conduction membranes are placed between the positive and negative electrodes, or adjacent to the negative electrode of a battery and in particular, of a lithium sulfur battery.