Polyacrylamide Polymer Electrolyte for High-Voltage Cathode Stability
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Solution Overview
Problem
Conventional lithium secondary batteries use liquid electrolytes that are inflammable and pose safety risks, while solid electrolytes face challenges in achieving high ionic conductivity, broad electrochemical window, mechanical/thermal stability, and compatibility with high-potential cathode materials like NMC622.
Innovation Solution
A polymer electrolyte comprising a polyacrylamide backbone encapsulates deep eutectic solvents and is compatible with high-potential electrodes, using specific acrylamide monomers and bisacrylamide crosslinkers to form a three-dimensional network that enhances cycling stability and mechanical flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolytes are used in lithium secondary batteries, then high ionic conductivity is achieved, but safety risks increase due to inflammability and leakage
Solution Approach 1:
The patent employs a composite solid electrolyte system combining a polyacrylamide polymer matrix with deep eutectic solvent and lithium salt. This composite structure integrates the safety and flexibility advantages of solid polymers with the high ionic conductivity of liquid electrolytes, achieving both safety and performance requirements simultaneously.
2Reliability
If conventional solid polymer electrolytes like PEO are used, then mechanical flexibility and thermal stability are improved, but anodic stability is limited to potentials around 4.0 V vs. Li+/Li
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer electrolyte by using polyacrylamide backbone with deep eutectic solvent instead of conventional PEO. This compositional parameter change raises the anodic stability limit to above 4.3 V vs. Li+/Li, enabling compatibility with high-potential cathode materials like NMC622 and NMC811.
3Reliability
If solid composite electrolytes are developed to improve safety, then EHS hazards are reduced, but difficulty in achieving high ionic conductivity and electrochemical stability increases
Solution Approach 1:
The deep eutectic solvent acts as an intermediary between the polyacrylamide polymer matrix and lithium ions. It facilitates ion transport through the polymer network while maintaining structural integrity, thereby achieving high ionic conductivity (above 10^-3 S/cm) and electrochemical stability simultaneously with improved safety.
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 polymer electrolyte exhibits excellent compatibility with high-potential cathodes, such as NMC622, and outperforms existing polymer electrolytes in cycling stability and safety, while maintaining flexibility and mechanical robustness.
Implementation Method 1
a polymer electrolyte comprising a polyacrylamide backbone which is particularly suitable for use with electrolyte compositions comprising a deep eutectic solvent
Implementation Method 2
solid composite electrolytes (SCE). These electrolytes comprise a liquid lithium-ion conducting electrolyte enclosed within a solid backbone or network
Data Source
AI summary
The present invention concerns polymer electrolytes comprising a polymer backbone derived from acrylamide monomers and bis-acrylamide crosslinkers which effectively encapsulate deep eutectic solvents (DES) and are compatible with high potential electrodes. The present invention further concerns composite cathodes and electrochemical cells comprising the polymer electrolyte, and uses thereof.