Organosulfur Cathode Polymer to Limit Polysulfide Dissolution
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Solution Overview
Problem
Lithium-sulfur batteries face issues with polysulfide dissolution leading to instability and low cyclability due to the 'shuttle effect,' which reduces their performance and energy density, despite advancements like sulfur encapsulation and copolymerization, which still limit sulfur content and introduce inert mass.
Innovation Solution
Development of a polymer or compound with a disulfide bridge and sulfur atoms, combined with a conductive material and binder, forming an organosulfur hybrid electrode material that reduces polysulfide dissolution and enhances electrochemical performance by incorporating elemental sulfur and electrochemically active organic segments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfur is encapsulated with electrochemically inactive organic monomers (e.g., polyaniline or 1,3-diisopropenylbenzene) to immobilize polysulfides, then battery stability and cyclability improve, but the amount of electrochemically active sulfur is limited to 58% by mass, reducing charge density and energy density
Solution Approach 1:
The invention changes the chemical nature of the polymer from electrochemically inactive to electrochemically active by introducing aromatic groups with delocalized electrons (e.g., phenylene, naphthalenediimide units) into the polymer backbone. This allows the polymer to participate in redox reactions while maintaining its structural role in immobilizing polysulfides, thereby increasing the active sulfur content beyond the 58% limit of traditional encapsulation approaches.
Solution Approach 2:
The invention creates a composite polymer structure combining electrochemically active aromatic segments with polysulfide-containing segments. This composite approach allows simultaneous achievement of polysulfide immobilization (through the polysulfide segments) and electrochemical activity (through the aromatic segments), resolving the contradiction between stability and charge density.
2Duration of action of stationary object
If electrochemically active organic polymers are used to reduce active material dissolution, then cyclability improves, but the polymer structure may limit sulfur content and introduce inert mass
Solution Approach 1:
The invention modifies the polymer structure to contain electrochemically active aromatic groups that can undergo redox reactions. This changes the polymer from a passive stabilizing matrix to an active electrochemical participant, allowing higher sulfur content while maintaining cyclability through both the polymer structure and the electrochemically active segments.
3Power
If carbon-sulfur composites (e.g., graphene-sulfur) are synthesized to increase conductivity and capacitance, then initial capacitance improves, but the material still suffers from polysulfide dissolution and capacitance loss equivalent to sulfur itself
Solution Approach 1:
The invention creates a molecular-level composite where polysulfide segments are covalently integrated into the polymer backbone rather than physically mixed with carbon materials. This molecular integration provides superior polysulfide immobilization compared to physical composites like graphene-sulfur, preventing dissolution while maintaining high capacitance through the electrochemically active aromatic groups.
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 proposed solution improves the capacity retention and cyclability of lithium-sulfur batteries by stabilizing the electrode material, maintaining high coulomb efficiency, and increasing energy density through the use of an organosulfur hybrid structure that limits polysulfide dissolution.
Implementation Method 1
a polymer or compound with a disulfide bridge and sulfur atoms, combined with a conductive material and binder, forming an organosulfur hybrid electrode material that reduces polysulfide dissolution
Implementation Method 2
A is chosen from among unsaturated groups allowing electron delocalization, for example, substituted or unsubstituted aryl and heteroaryl groups... electrochemically active organic segments
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
The present technology relates to an organic sulfur-containing compound or polymer for use in a positive electrode material, especially in lithium batteries. More specifically, the use of this sulfur-containing compound or polymer as active electrode material makes it possible to combine sulfur and an active organic cathode material. The present technology also relates to the use of the organic sulfur-containing compound or polymer as defined here as solid polymer electrolyte (SPE) or as additive for electrolyte, especially in lithium batteries.