Composite Solid Polymer Electrolyte for Solid-State Lithium Batteries
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Solution Overview
Problem
Current solid-state lithium batteries face challenges with low ionic conductivity, mechanical properties, and limited cycling stability due to poor electrode-electrolyte interfacial compatibility, which hinders their application in high-energy density and long-life span batteries.
Innovation Solution
The development of composite solid polymer electrolytes using a hybrid polymer matrix with LiTFSI salt and LLZTO ceramic filler, combined with organic cathode materials like perylene-3,4,9,10-tetracarboxylic dianhydride, enhances ionic conductivity, mechanical strength, and thermal stability, while improving electrode-electrolyte compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PEO solid electrolyte matrix is used, then low cost and high compatibility with lithium salts are achieved, but low room-temperature ionic conductivity, poor mechanical properties, and narrow electrochemical window occur
Solution Approach 1:
The patent uses a composite solid polymer electrolyte consisting of PVDF polymer matrix combined with LiTFSI salt and LLZTO ceramic filler. This composite structure achieves high room-temperature ionic conductivity (10^-4 S·cm^-1) while maintaining mechanical strength and electrochemical stability, resolving the contradiction between ease of manufacture and reliability.
Solution Approach 2:
The patent changes the polymer matrix from PEO to PVDF, which fundamentally alters the electrochemical stability window from under 3.8V to over 4V vs Li/Li+. This parameter change enables the electrolyte to withstand higher voltages and achieve better ionic conductivity while maintaining compatibility with lithium salts.
2Reliability
If ceramic filler is added to PVDF-based composite solid polymer electrolytes, then ionic conductivity is enhanced, but simultaneous improvement in mechanical property and thermal stability has not been achieved
Solution Approach 1:
The patent creates a triple-component composite system where PVDF polymer matrix, LiTFSI salt, and LLZTO ceramic filler work synergistically. The LLZTO filler enhances ionic conductivity through ceramic-polymer interface interactions, while the PVDF matrix provides mechanical strength and flexibility, achieving simultaneous improvement in both ionic conductivity and mechanical properties.
Solution Approach 2:
The patent optimizes the local distribution and concentration of LLZTO ceramic filler within the PVDF matrix to achieve optimal performance. The filler is dispersed to create conductive pathways for lithium ions while maintaining the overall mechanical integrity of the polymer matrix, balancing ionic conductivity and mechanical strength.
3Use of energy by moving object
If inorganic metal oxide-based cathode materials are used, then high energy density is achieved, but expensive cost, scarce resources, and environmental unfriendliness occur
Solution Approach 1:
The patent replaces expensive and scarce inorganic metal oxide cathode materials with organic cathode materials that are abundant, low-cost, and environmentally friendly. The organic materials can be derived from renewable resources and are less harmful to the environment, addressing the contradiction between energy density and environmental impact.
Solution Approach 2:
The patent changes the cathode material class from inorganic to organic, fundamentally altering the resource availability, cost, and environmental impact parameters while maintaining acceptable energy density through proper molecular design of the organic cathode materials.
4Ease of manufacture
If organic cathode materials are used with liquid electrolytes, then low cost and eco-friendliness are achieved, but dissolution and shuttle issues occur resulting in rapid capacity decline
Solution Approach 1:
The patent introduces a solid polymer electrolyte as an intermediary between the organic cathode and lithium anode. This solid electrolyte prevents direct contact and dissolution of the organic cathode materials, eliminating the shuttle effect while maintaining the low-cost and eco-friendly advantages of organic cathodes, thereby achieving both affordability and long cycling stability.
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 solution achieves high room-temperature ionic conductivity, wide voltage windows, excellent mechanical properties, and enhanced thermal safety, leading to improved cycling stability and extended life span of solid-state lithium batteries.
Implementation Method 1
introducing ceramic filler can further enhance the ionic conductivity of solid polymer electrolyte due to the interaction between ceramic filler with both polymer matrix and salt anions
Implementation Method 2
the introduction of solid-state electrolytes into Li-organic batteries not only offers the possibility to fully address the dissolution issue of organic cathodes
Implementation Method 3
PVDF has been reported to be a suitable polymer matrix with high room-temperature ionic conductivity (about 10−4 S·cm−1)
Data Source
AI summary
Composite solid polymer electrolytes (SPE), organic cathode electrodes, and solid-state lithium batteries (SLBs) that incorporate the SPE and/or the organic cathode electrodes. The composite solid polymer electrolytes include a hybrid polymer matrix, an LiTFSI salt dispersed in the matrix polymer matrix, and an LLZTO ceramic filler dispersed in the matrix polymer matrix. The organic cathode electrodes contain perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA).