Polyacrylamide Polymer Electrolyte for High-Voltage Li-Ion Cathodes
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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, and mechanical/thermal stability, especially when combined with high-potential cathode materials like NMC622.
Innovation Solution
A polymer electrolyte comprising a polymer network based on specific N-dialkyl (meth)acrylamide monomers encapsulates deep eutectic solvents and is compatible with high-potential electrode active materials, such as NMC622, allowing for high anodic 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 uses a composite polymer electrolyte system combining polyacrylamide polymer matrix with deep eutectic solvent (DES) and lithium salt, creating a material that integrates the safety advantages of solid electrolytes with the high ionic conductivity of liquid electrolytes. The DES-LiClO4 complex within the polymer network provides both safety and performance.
2Strength
If PEO-based polymer electrolytes are used, then mechanical flexibility is achieved, but anodic stability is limited to around 4.0V vs Li+/Li
Solution Approach 1:
The patent changes the chemical composition from PEO to polyacrylamide-based polymer and uses deep eutectic solvent instead of conventional liquid electrolytes. This composition change increases anodic stability to 4.7V vs Li/Li+ while maintaining mechanical flexibility, enabling compatibility with high-voltage cathode materials like NMC622 and NMC811.
3Temperature
If solid composite electrolytes are produced with inorganic backbones, then thermal stability is improved, but compatibility with high-potential cathode materials deteriorates
Solution Approach 1:
The patent creates a composite material system where polyacrylamide polymer provides the backbone structure and deep eutectic solvent (DES) with lithium salt provides the ionic conducting phase. This composite approach achieves both thermal stability from the solid polymer matrix and high anodic stability (4.7V) from the DES-LiClO4 complex, enabling use with high-potential cathodes.
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 cycling stability and compatibility with high-potential cathode materials, providing a safe and stable energy storage solution for lithium-ion batteries.
Implementation Method 1
a polymer electrolyte which encapsulates a liquid electrolyte composition
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 dialkylacrylamide monomers 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.