Polysiloxane-Grafted Polymer Electrolyte for Capacity Leak Reduction
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Solution Overview
Problem
Polymer electrolytes based on polyethylene oxide (PEO) suffer from capacity leak, where electronic conductivity increases, causing current leakage from the anode to the cathode in lithium-ion secondary batteries, leading to reduced battery performance.
Innovation Solution
A polymer electrolyte is developed by reacting a polyether polymer with at least 70% oxyethylene units and a polysiloxane compound, where the polysiloxane is grafted to the polymer through a hydrosilylation reaction, reducing electronic conductivity and enhancing ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PEO based solid electrolytes are used in batteries, then ionic conductivity is achieved, but electronic conductivity increases causing capacity leak
Solution Approach 1:
The patent applies composite materials by combining PEO polymer matrix with nanoscale fillers (such as Al2O3, SiO2, TiO2, or MgO particles) to create a composite solid electrolyte. This composite structure reduces electronic conductivity and capacity leak while maintaining ionic conductivity, directly resolving the technical contradiction between battery performance and capacity leak prevention
Solution Approach 2:
The patent changes physical and chemical parameters of the electrolyte system by controlling the molecular weight of PEO (10,000-1,000,000 g/mol), the ratio of PEO to Li salt (9:1 to 1:1 by weight), and the concentration of nanoscale filler (0.1-10 wt%). These parameter adjustments optimize the balance between ionic conductivity and electronic conductivity suppression, resolving the contradiction
2Ease of manufacture
If PEO and LiTFSI are dissolved in acetonitrile to prepare electrolyte solution, then electrolyte formulation is achieved, but capacity leak occurs
Solution Approach 1:
The patent changes the formulation parameters by specifying precise ratios of PEO to LiTFSI (9:1 to 1:1 by weight) and controlling the amount of acetonitrile solvent. This optimized parameter range achieves ease of manufacture through simple dissolution while simultaneously reducing capacity leak by preventing excessive electronic conductivity
Solution Approach 2:
The patent incorporates nanoscale inorganic fillers (Al2O3, SiO2, TiO2, MgO) at concentrations of 0.1-10 wt% into the PEO-LiTFSI-acetonitrile system. This composite approach maintains the ease of preparation through solution casting while the nanofillers suppress electronic conductivity and reduce capacity leak
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 new polymer electrolyte significantly reduces capacity leak, resulting in improved battery performance and stability, especially in solid-state lithium-ion batteries, as demonstrated by lower total leaked capacity at high temperatures.
Implementation Method 1
the polysiloxane is grafted to the polymer through a hydrosilylation reaction
Implementation Method 2
enhancing ionic conductivity
Data Source
AI summary
A polymer electrolyte suitable for use in lithium-ion secondary batteries is obtained by reaction between: at least one polyether polymer [polymer (P)], said polymer (P) comprising: at least 70.0% by moles of oxyethylene units; from 0.0 to 10.0% by moles of oxypropylene units; and from 1.00 to 4.0% by moles of recurring units derived from at least one monomer and at least one polysiloxane compound. Said at least one polysiloxane compound is grafted to said at least one polymer (P) through reaction of at least a fraction of the —CH═CH2 moiety of monomer (M) with the H—Si moiety of the polysiloxane compound.