Boron-Fluorine Solid Polymer Electrolyte for High-Voltage Li-Ion Cells
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Solution Overview
Problem
Existing lithium ion batteries face issues such as thermal runaway, poor processability, high cost, low conductivity, and low high-voltage resistance in polymer electrolytes, particularly in solid-state batteries, which affect safety and performance.
Innovation Solution
A polymer electrolyte containing boron and fluorine structures is developed, with a specific molecular design and preparation method involving vinyl boron fluorine and vinyl polyether monomers, lithium salts, and crosslinking agents to enhance high voltage resistance, compatibility with lithium metal, and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyethylene oxide (PEO) is used as the main polymer electrolyte, then the electrolyte has good processability and flexibility, but the conductivity and high-voltage resistance are low
Solution Approach 1:
The patent uses a composite polymer structure combining PEO chains with boron-containing cyclic structures and fluorinated side groups. The PEO provides processability and flexibility, while the boron-containing cyclic structures with lithium salts improve conductivity through coordinated lithium ion transport, and the fluorinated groups enhance high-voltage resistance by stabilizing the electrolyte against oxidation.
Solution Approach 2:
The patent modifies the polymer structure by introducing boron-containing cyclic structures and fluorinated side groups to change the chemical and physical parameters of PEO. These structural modifications increase lithium ion conductivity by creating favorable coordination environments and raise the oxidation stability to withstand higher voltages while maintaining the base PEO's processability.
2Object-affected harmful factors
If phosphorus-containing structures are introduced to improve non-flammability, then the electrolyte becomes non-flammable, but epoxy structures are introduced that are not resistant to high voltage, resulting in partial oxidation and decomposition
Solution Approach 1:
The patent removes the problematic epoxy structures from the polymer chain and instead introduces fluorinated side groups attached to the boron-containing cyclic structures. This extraction eliminates the high-voltage instability while retaining the flame-retardant properties through alternative chemical composition.
Solution Approach 2:
The patent applies different functional groups at different locations: the boron-containing cyclic structure in the main chain provides structural stability and lithium coordination, while fluorinated side groups provide both flame retardancy and high-voltage resistance through their electron-withdrawing effect and thermal stability, avoiding the oxidation issues of epoxy groups.
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 improved high voltage resistance, good interface contact, and high conductivity, enabling the production of lithium ion batteries with high energy density and safety.
Implementation Method 1
adding a vinyl boron fluorine monomer, a vinyl polyether monomer, a modified monomer, and a functional polymer into a solvent, and stirring in an atmosphere of nitrogen or inert gas until uniform, and then adding an initiator, and after a reaction is finished
Implementation Method 2
The polymer electrolyte exhibits improved high voltage resistance, good interface contact, and high conductivity
Implementation Method 3
adding a crosslinking agent to obtain a mixed solution, and uniformly coating the mixed solution on a mold, and placing it into a vacuum drying oven and introducing nitrogen or inert gas therein for reaction
Data Source
AI summary
The preparation method of the solid polymer electrolyte includes the following steps: S1, adding a vinyl boron fluorine monomer, a vinyl polyether monomer, a modified monomer, and a functional polymer into a solvent, adding an initiator for reaction, and after performing a purification treatment to obtain a polymer system B; S2, adding the polymer system B, a lithium salt, a filler, and an auxiliary agent into a solvent, and adding a crosslinking agent to obtain a mixed solution, and coating the mixed solution on a mold uniformly for reaction; S3, obtaining the solid polymer electrolyte. The obtained solid polymer electrolyte, a positive electrode plate, and a negative electrode plate are assembled into a solid-state battery core, and then a tab welding, a heat treatment, and an encapsulation treatment are performed to obtain a lithium ion battery.