Polyurethane Separator for Energy Storage Devices
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Solution Overview
Problem
Current energy storage devices, such as batteries and capacitors, face limitations in terms of energy density, durability, size, weight, and recharge time, particularly in portable and mobile applications, where improved ion selectivity, permeability, and mechanical stability are needed while maintaining cost-effectiveness.
Innovation Solution
A separator for energy storage devices is developed using a polycarbonate-based polyurethane resin that allows ion transport while preventing electron flow, incorporating a metal or ammonium salt and swelling with organic solvents to enhance ion conductivity and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional separators are used in energy storage devices, then basic ion transport is achieved, but ion selectivity and conductivity are insufficient
Solution Approach 1:
The separator is constructed as a composite material comprising a porous substrate combined with a polyurethane coating layer containing lithium salt. This composite structure integrates the mechanical strength and porosity of the substrate with the ion-conducting properties of the polyurethane-lithium salt composite, achieving both high ion selectivity and enhanced conductivity simultaneously
Solution Approach 2:
The separator utilizes a porous substrate structure with controlled pore size and distribution. The porosity allows efficient ion transport pathways while the pore architecture provides ion selectivity by enabling selective passage of ions based on size and charge, thus improving both ion conductivity and selectivity
2Productivity
If separator thickness is reduced to improve ion conductivity, then ion transport efficiency increases, but mechanical stability deteriorates
Solution Approach 1:
The composite structure combines a mechanically robust porous substrate with a functional polyurethane-lithium salt coating layer. This allows the use of thinner overall separator design that maintains mechanical stability through the substrate while the coating layer provides sufficient ion conductivity without requiring excessive thickness
Solution Approach 2:
Different regions of the separator have specialized functions: the porous substrate provides mechanical strength and structural integrity, while the polyurethane-lithium salt coating layer localized on the substrate surface provides enhanced ion conductivity and selectivity. This local differentiation allows optimization of each region for its specific function
3Productivity
If organic solvents are used to swell the polyurethane separator, then ion conductivity increases, but swelling control becomes difficult
Solution Approach 1:
The polyurethane coating is modified by incorporating lithium salt, which changes the physical and chemical parameters of the polymer matrix. This modification alters the swelling behavior of the polyurethane when exposed to organic solvents, providing more controlled and predictable swelling that enhances ion conductivity while maintaining structural stability
Solution Approach 2:
The combination of polyurethane and lithium salt creates a composite material with tailored swelling properties. The lithium salt incorporation modifies the polymer's interaction with organic solvents, enabling controlled swelling that improves ion conductivity without excessive or uncontrolled expansion that would compromise separator integrity
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 separator provides improved ion selectivity and conductivity, increased mechanical stability, and reduced swelling, making it suitable for non-aqueous devices, enhancing the performance and efficiency of energy storage devices in various applications.
Implementation Method 1
a separator comprising an ion-permeable, i.e., ion transporting, film or membrane
Implementation Method 2
which separator, in many embodiments, is swelled by an organic solvent
Data Source
AI summary
Energy storage devices are improved by incorporating polyurethane separators, which separators comprise polyurethane polymers prepared by curing a polycarbonate based polyurethane prepolymer, which polyurethane polymers often further comprise metal or ammonium salts and are often swelled by an organic solvent.