PVDF Solid Polymer Electrolyte for Conductive Stable Batteries
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Solution Overview
Problem
Solid-state electrolytes face challenges such as poor electrolyte-electrode contact and reduced ion conductivity, hindering their practical implementation in energy storage devices.
Innovation Solution
A solid polymer electrolyte composition comprising polyvinylidene fluoride (PVDF) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) with a mass content of LiTFSI greater than PVDF, and optionally including lithium lanthanum zirconate oxide (LLZO) and plasticizers like succinonitrile (SN) or vinylene carbonate (VC), is used to enhance mechanical stability and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid-state electrolytes are used to replace liquid electrolytes, then safety is improved by eliminating flammable solvents, but ion conductivity deteriorates due to reduced ion movement in solid medium
Solution Approach 1:
The patent uses a composite solid polymer electrolyte consisting of PVDF polymer matrix combined with LiTFSI lithium salt. This composite structure allows the material to maintain the safety advantages of solid-state electrolytes while achieving sufficient ion conductivity through the synergistic interaction between the polymer chains and lithium ions, resolving the contradiction between safety and ion conductivity.
Solution Approach 2:
The patent optimizes the composition parameters of the solid polymer electrolyte, specifically using a mass ratio of LiTFSI to PVDF greater than 1:1 (higher lithium salt content than conventional formulations). This parameter change enhances ion conductivity by increasing the concentration of mobile lithium ions while maintaining the solid-state safety advantages, thus resolving the contradiction between safety and ion conductivity.
2Reliability
If solid-state electrolytes are used, then reliability is improved by reducing fire risk, but contact between electrolyte and electrode deteriorates due to solid-solid interface issues
Solution Approach 1:
The patent employs a flexible solid polymer electrolyte film made from PVDF that can conform to the electrode surfaces. This flexibility allows the solid electrolyte to maintain good physical contact with the electrodes despite the solid-state interface challenges, resolving the contradiction between fire safety and contact quality.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the solid polymer electrolyte by adjusting the lithium salt content and polymer structure, enhancing the material's flexibility and adaptability to electrode surfaces. This enables better solid-solid contact while maintaining the inherent fire safety advantages of solid-state electrolytes.
3Quantity of substance
If higher LiTFSI content is used to improve ion conductivity, then ion conductivity is improved, but mechanical stability deteriorates
Solution Approach 1:
The patent creates a balanced composite formulation where LiTFSI lithium salt is dispersed within the PVDF polymer matrix. This composite structure allows the lithium-rich composition (mass ratio LiTFSI/PVDF > 1) to achieve high ion conductivity while the PVDF polymer framework provides the necessary mechanical stability, resolving the contradiction between ion conductivity and mechanical strength.
Solution Approach 2:
The patent optimizes the local distribution and interaction between LiTFSI and PVDF components, ensuring that the high lithium salt content regions provide ion conductivity while the polymer matrix regions maintain mechanical integrity. This local quality optimization allows the electrolyte to simultaneously achieve high ion conductivity and adequate mechanical 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 proposed electrolyte composition improves mechanical strength and ion conductivity, enabling stable and efficient operation of solid-state batteries.
Implementation Method 1
reduced ion conductivity in a solid medium
Implementation Method 2
enhance mechanical stability
Data Source
AI summary
Aspects of the disclosure provide an energy storage device that can include a cathode, an anode, and a solid polymer electrolyte. The solid polymer electrolyte can include polyvinylidene fluoride (PVDF) and bis(trifluoro-methanesulfonyl)imide (LiTFSI). A mass content of the LiTFSI can be greater than a mass content of the PVDF. The solid polymer electrolyte can have a structural composition based on forming the solid polymer electrolyte using a solution comprising a solid content, comprising the PVDF and LiTFSI, and one or more solvents for dissolving the solid content, the solid content being approximately 0.19 or greater of the solution.