Crosslinked Solid Polymer Electrolyte for Dendrite-Resistant Li Batteries
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Solution Overview
Problem
Conventional solid polymer electrolytes for lithium batteries face challenges with limited ionic conductivity and mechanical stability, particularly at high temperatures, which can lead to lithium dendrite growth and short-circuiting issues.
Innovation Solution
A method for preparing a solid polymer electrolyte film using a composition of cyclic monomers, a crosslinking agent, and an ionic conductive salt, which forms a crosslinked polymer network without plasticizers, enhancing ionic conductivity and mechanical stability, allowing the electrolyte to function effectively up to 150°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional solid polymer electrolytes are used, then mechanical stability is improved, but ionic conductivity deteriorates
Solution Approach 1:
The patent uses a composite system combining poly(ε-caprolactone) polymer matrix with lithium bis(trifluoromethanesulfonyl)imide salt to create a solid polymer electrolyte that achieves both mechanical stability and good ionic conductivity through the synergistic interaction between polymer and salt components
Solution Approach 2:
The patent optimizes the salt-to-polymer ratio parameter to achieve the best balance between mechanical stability and ionic conductivity, demonstrating that adjusting compositional parameters can resolve the contradiction between these two properties
2Reliability
If operating temperature is increased to improve ionic conductivity, then ionic conductivity is improved, but thermal stability deteriorates
Solution Approach 1:
The patent achieves high ionic conductivity (≥10−6 S·cm−1 at 25°C and ≥10−5 S·cm−1 at 60°C) by optimizing the electrolyte composition rather than relying on high operating temperatures, thereby maintaining thermal stability while achieving good ionic conductivity at lower temperatures
3Reliability
If high operating temperature is used to enhance ionic conductivity, then ionic conductivity is improved, but safety deteriorates due to lithium dendrite growth
Solution Approach 1:
The patent achieves satisfactory ionic conductivity at low operating temperatures (25-60°C) through optimized composition, avoiding the high temperatures that would cause lithium dendrite growth and safety issues
Solution Approach 2:
The patent uses a simple poly(ε-caprolactone) polymer without complex additives or plasticizers, achieving both safety and performance through a minimalist approach that avoids dendrite-forming conditions
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 resulting solid polymer electrolyte exhibits excellent ionic conductivity (≥10−6 S·cm−1 at 25°C and ≥10−5 S·cm−1 at 60°C) and improved thermal and electrochemical stability, preventing lithium dendrite growth and enabling high-energy density battery performance without the need for additives.
Implementation Method 1
at least one organic molecule, called 'crosslinking agent', bearing at least two reactive functions, said molecule being able to allow, under the action of external stimulation, in particular under the action of heat and/or UV radiation, crosslinking of said (co)polymer or (co)polymers by reaction with the hydroxyl functions of said (co)polymer or (co)polymers
Implementation Method 2
at least one ionic conductive salt, in particular a lithium salt
Data Source
AI summary
A method for preparing a film of solid polymer electrolyte, including: (i) providing a composition including, in one or more solvents, at least one (co)polymer of at least one cyclic monomer selected from lactones and cyclic carbonates with five to eight ring members; the (co)polymer or (co)polymers having free terminal hydroxyl functions; at least one crosslinking agent, at least one ionic conductive salt; and optionally, in the case of a crosslinking agent bearing at least one photosensitive reactive function, at least one photoinitiator compound; (ii) forming a dry film from the composition, in conditions unfavourable to crosslinking of the (co)polymer or (co)polymers; and (iii) bringing the film into conditions favourable to crosslinking of the (co)polymer or (co)polymers to form the film of solid polymer electrolyte. Also disclosed is a film of solid polymer electrolyte and use thereof in an electrochemical system, in particular in a lithium battery.