Conductive Polymer Electrolyte for Low-Resistance Solid-State Batteries
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Solution Overview
Problem
Conventional lithium secondary batteries face safety issues like leakage and explosion due to liquid electrolytes, and existing solid electrolytes have low ionic and electronic conductivity, hindering the development of all-solid-state battery systems.
Innovation Solution
A polymer material comprising a polythiophene-based polymer blended with a conductive polymer, such as poly-(3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS), is developed to enhance ionic and electronic conductivity, functioning as an electrolyte, binder, and conductive material in lithium secondary batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolyte is used in lithium secondary battery, then battery performance is maintained, but safety problems occur such as leakage, volatilization and explosion
Solution Approach 1:
The patent transitions the electrolyte from liquid phase to solid polymer gel phase. This phase transition eliminates the safety issues associated with liquid electrolytes (leakage, volatilization, explosion) while maintaining ionic conductivity through the gel structure formed by polyethylene oxide and lithium salt complex
2Reliability
If solid polymer electrolyte is used to improve safety, then ionic conductivity is improved, but interface resistance increases
Solution Approach 1:
The patent optimizes the molecular weight and composition ratios of polyethylene oxide and lithium salt to achieve optimal ionic conductivity. By controlling the PEG:Lithium salt molar ratio and PEG molecular weight distribution, the gel structure parameters are tuned to balance ionic conductivity and interface resistance
Solution Approach 2:
The patent creates a composite gel electrolyte system combining polyethylene oxide polymer matrix with lithium salt complexes. This composite structure provides both the mechanical stability needed for solid-state operation and the ionic conduction pathways necessary for low interface resistance
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 material significantly reduces interfacial resistance and improves battery performance by achieving high ionic and electronic conductivity, enabling the creation of more efficient all-solid-state lithium secondary batteries with reduced weight and simplified manufacturing.
Implementation Method 1
the solid polymer electrolyte having high ionic conductivity (>10−4 S/cm, 25° C.)
Implementation Method 2
if an ionic and electronic conductive polymer material has been developed
Data Source
AI summary
A polymer material for a lithium secondary battery having ionic conductivity and electronic conductivity at the same time, and a method for preparing the same. The polymer material includes a polythiophene-based polymer and a conductive polymer, and the polymer material may be formed by forming a polythiophene-based polymer, forming a conductive polymer, and heat-treating the polythiophene-based polymer and the conductive polymer.