Peptide-Mimetic Sulfur Catalyst for Faster Li-S Battery Redox
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Solution Overview
Problem
The shuttle effect and slow redox kinetics in lithium-sulfur batteries limit their practical application due to the diffusion of soluble polysulfides and high energy barriers in sulfur conversion reactions, leading to self-discharge and low Coulombic efficiency.
Innovation Solution
Amino acid concatemers, specifically Ser, His, and Asp, are used to construct a peptide-based mimetic enzyme catalyst on a conductive matrix, enhancing the conversion of polysulfides through electrostatic attraction, nucleophilic attack, and Li+ transfer, improving redox reaction kinetics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If natural enzyme is used as catalyst, then catalytic ability is improved, but structure complexity increases and structure-activity relationship becomes difficult to interpret
Solution Approach 1:
The patent creates a simplified copy of natural enzyme's catalytic function using amino acid concatemers (Ser-His-Asp) that replicate the essential catalytic triad structure without the full complexity of natural enzymes. This copy preserves the catalytic ability while reducing structural complexity to just three amino acids, making the structure-activity relationship interpretable and the catalytic mechanism clear.
2Productivity
If sulfur conversion reaction is accelerated, then redox kinetics is improved, but energy barrier remains high for liquid-solid and solid-solid phase conversion
Solution Approach 1:
The amino acid concatemer acts as an intermediary substance that facilitates the high-energy sulfur conversion reaction. The Ser-His-Asp triad provides alternative reaction pathways with lower activation energy, mediating between the liquid polysulfide phase and solid Li2S phase, thereby accelerating redox kinetics while reducing the energy barrier for phase conversion.
Solution Approach 2:
The patent changes the chemical parameters at the catalyst surface by introducing specific amino acid residues with different functional groups (hydroxyl in Ser, imidazole in His, carboxyl in Asp). These parameter changes create multiple active sites that can interact with polysulfides through different mechanisms, lowering the energy barrier for sulfur conversion and improving redox kinetics.
3Quantity of substance
If polysulfide conversion is incomplete, then capacity loss occurs, but slow reaction kinetics prevents complete conversion at discharge end
Solution Approach 1:
The amino acid concatemer performs preliminary action by continuously catalyzing the conversion reaction throughout the discharge process. The Ser-His-Asp triad maintains high catalytic activity even at low polysulfide concentrations near the end of discharge, ensuring complete conversion to Li2S and preventing capacity loss from unconverted polysulfides.
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 synergistic effect of Ser, His, and Asp accelerates polysulfide conversion, promoting efficient Li+ transmission and improving battery performance by reducing polarization and maintaining capacity over multiple cycles.
Implementation Method 1
enhancing the conversion of polysulfides through electrostatic attraction
Implementation Method 2
enhancing the conversion of polysulfides through electrostatic attraction, nucleophilic attack
Implementation Method 3
Amino acid concatemers, specifically Ser, His, and Asp, are used to construct a peptide-based mimetic enzyme catalyst on a conductive matrix, enhancing the conversion of polysulfides
Implementation Method 4
the amino acid concatemer is compounded on the conductive matrix... the carbon material has high conductivity
Implementation Method 5
since the sulfur conversion reaction involves the conversion between liquid-solid and solid-solid phases
Data Source
AI summary
The invention provides an amino acid concatemer synergistic sulfur conversion catalyst for lithium-sulfur battery and its preparation method and application. The invention uses peptide-based materials serine (Ser), histidine (His) and aspartic acid (Asp) to construct a peptide-based mimetic enzyme, that is, Ser-His-Asp catalytic triplet, which retains the function of the enzyme while reducing the inherent complexity of the enzyme. The synergistic effect between the three significantly improves the redox reaction kinetics of lithium-sulfur battery, promotes the efficient conversion of polysulfide, accelerates Li+ transmission, and improves battery performance.