Composite Solid Polymer Electrolyte for Lithium Batteries
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Solution Overview
Problem
Conventional lithium ion batteries face safety concerns due to flammability and thermal instability of liquid electrolytes, and solid polymer electrolytes suffer from low ionic conductivity and dendrite formation issues, limiting their application in energy storage devices.
Innovation Solution
A composite solid electrolyte material comprising a cross-linked polymer, lithium salt, plasticizer, and filler material is developed, which enhances ionic conductivity and mechanical strength, preventing dendrite growth and improving cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If liquid electrolytes are used to achieve high ionic conductivity, then ionic conductivity is improved, but thermal stability and safety deteriorate due to flammability
Solution Approach 1:
The patent employs a composite solid electrolyte system combining polymer matrix (PEO or PEG), lithium salt (LiClO4, LiBF4, or LiPF6), plasticizer (EC or PC), and filler material (Al2O3, TiO2, or SiO2). This composite structure achieves ionic conductivity of 10^-3 S/cm at room temperature while providing thermal stability and fire resistance, resolving the contradiction between conductivity and safety.
2Reliability
If solid polymer electrolytes are used to improve thermal stability, then safety is improved, but ionic conductivity deteriorates due to crystalline states below 60°C
Solution Approach 1:
The patent modifies the physical and chemical parameters of the polymer electrolyte by incorporating plasticizers (EC or PC) at 30-70 wt% and filler materials at 10-50 wt%, which suppress crystallization and maintain the polymer in an amorphous state at room temperature. This enables ionic conductivity of 10^-3 S/cm while preserving thermal stability above 100°C.
Solution Approach 2:
The composite structure with filler materials (Al2O3, TiO2, or SiO2) disrupts the crystalline packing of PEO chains, maintaining amorphous morphology and enabling high ionic conductivity at room temperature while preserving the inherent thermal stability of the polymer matrix.
3Reliability
If solid polymer electrolytes are used to improve thermal stability, then safety is improved, but mechanical strength deteriorates leading to dendrite formation
Solution Approach 1:
The incorporation of filler materials (Al2O3, TiO2, or SiO2) at 10-50 wt% into the polymer matrix significantly enhances mechanical strength and rigidity. The filler particles act as physical barriers that prevent dendrite propagation while maintaining the softness needed for electrode contact, resolving the contradiction between mechanical strength and thermal 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 composite electrolyte achieves high ionic conductivity above 10^-3 S/cm at room temperature, maintaining mechanical strength and stability, thereby enhancing the performance and safety of all-solid-state lithium batteries.
Implementation Method 1
The ion transport in polymer electrolyte (i.e., lithium salt-doped polymer) is assisted by segmental motion of PEO chains in the amorphous state
Implementation Method 2
Increases in performance result in part from improved polymer chain mobility, polymer recrystallization kinetics, and increased mechanical strength
Implementation Method 3
Embodiments of the electrolyte materials provide increased mechanical strength that enables improvement of battery cycle-life relative to conventional polymer electrolytes
Implementation Method 4
initiating a cross linking reaction with the cross-linking initiator, thereby converting the polymer compound to a solid, cross-linked polymer compound
Data Source
AI summary
The present application is directed to compositions and methods of preparing electrolyte materials. The electrolyte materials prepared according to compositions and methods described herein comprise enhanced electrochemical properties and find utility in any number of electrical devices, for example, in lithium batteries.