Aqueous Lithium Sulfur Battery Using Solid Mediator
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium sulfur batteries face challenges in commercialization due to issues with the sulfur electrode, including low water reactivity and hydrolysis of dissolved lithium sulfide, which affect cell integrity and safety, and the need for improved voltage stability and high solubility of active sulfur species.
Innovation Solution
An aqueous lithium sulfur battery cell design with a protected lithium anode and a cathode comprising a solid electron transfer medium, using an aqueous electrolyte with high water content to dissolve active sulfur species, and incorporating non-aqueous solvents to enhance performance, while maintaining lithium ion communication without direct contact between the anode and electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an aqueous electrolyte is used to dissolve active sulfur species, then solubility and ionic conductivity are improved, but hydrolysis of lithium sulfide and water reactivity issues worsen
Solution Approach 1:
A solid electron transfer medium is introduced as an intermediary between the aqueous electrolyte and the lithium anode. This medium allows lithium ion communication while preventing direct contact between water and the lithium anode, thereby eliminating hydrolysis reactions. The solid medium acts as a mediator that enables ionic conductivity without the harmful side reactions that would occur with direct aqueous contact.
Solution Approach 2:
The patent changes the physical state parameter of the electrolyte interface by using a solid electron transfer medium instead of direct liquid contact. This parameter change allows the system to maintain high solubility of sulfur species in the aqueous phase while preventing the harmful hydrolysis reaction by altering the contact interface between water and reactive lithium species.
2Reliability
If the anode electroactive material is isolated from direct contact with the aqueous electrolyte, then safety and cell integrity are improved, but lithium ion communication may be hindered
Solution Approach 1:
The solid electron transfer medium serves as an intermediary layer that enables lithium ion communication while maintaining physical isolation. This single-component mediator simplifies the overall structure compared to multi-layer protective coatings or complex separation systems, as it performs both the isolation and ion transport functions in one element.
3Quantity of substance
If water content in the catholyte is increased, then solubility of sulfur species and ionic conductivity are improved, but voltage stability may be affected
Solution Approach 1:
The solid electron transfer medium acts as a stable intermediary that buffers the electrochemical interface. This allows the use of high water content catholytes for improved solubility and conductivity while the solid medium maintains voltage stability by providing a consistent, non-aqueous interface for electron transfer, effectively decoupling the benefits of high water content from its potential stability issues.
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 design achieves high solubility and conductivity for active sulfur species, enabling efficient electrochemical reactions, improved safety through reduced hydrolysis, and extended operating potential range, facilitating deep discharge and high current drain capabilities.
Implementation Method 1
the presence of water provides a number of benefits, including high solubility for active sulfur species, including lithium sulfide (Li2S), very high ionic conductivity even at high sulfur concentrations
Implementation Method 2
the anode electroactive material is isolated from direct contact with the aqueous electrolyte... configured in the anode structure to be in lithium ion communication with the aqueous electrolyte
Implementation Method 3
it contains dissolved active sulfur species that undergo electrochemical redox at the cathode during discharge and charge
Data Source
AI summary
Provided are lithium sulfur battery cells that use water as an electrolyte solvent. In various embodiments the water solvent enhances one or more of the following cell attributes: energy density, power density and cycle life. Significant cost reduction can also be realized by using an aqueous electrolyte in combination with a sulfur cathode. For instance, in applications where cost per Watt-Hour (Wh) is paramount, such as grid storage and traction applications, the use of an aqueous electrolyte in combination with inexpensive sulfur as the cathode active material can be a key enabler for the utility and automotive industries, providing a cost effective and compact solution for load leveling, electric vehicles and renewable energy storage.