Crosslinked Cellulose Nanomaterial Membrane for Redox Flow Battery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Redox Flow Battery (RFB) membranes, particularly those made of Nafion™, suffer from poor barrier properties against redox component crossover, high cost, and environmental concerns, limiting their sustainability and energy density.
Innovation Solution
A crosslinked cellulose nanomaterial membrane with chemically modified aldehyde and sulfo groups is developed, providing improved stability and ion selectivity to prevent redox component leakage, achieved through oxidation and sulfonation of cellulose fibers followed by mechanical processing and dewatering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional dialysis membranes are used for separation, then size selection is allowed, but ion selectivity is absent resulting in leakage of redox components
Solution Approach 1:
The membrane material parameters are fundamentally changed from conventional dialysis membranes to crosslinked cellulose nanomaterial with specific chemical modifications. The cellulose nanomaterial is oxidized to introduce aldehyde groups, then sulfonated to create charged sulfo groups that provide ion selectivity while maintaining size-based separation capabilities
Solution Approach 2:
The membrane is constructed as a composite material system combining cellulose nanomaterial with crosslinking agents and sulfonation groups. This composite structure integrates the size-exclusion properties of cellulose nanofibrils with the ion-selective properties of charged sulfo groups, achieving both size selection and prevention of redox component leakage
2Reliability
If Nafion membrane is used for ion conductivity and separation, then ionic conductivity is achieved, but cost and environmental issues increase
Solution Approach 1:
The patent replaces expensive Nafion membranes with a cost-effective cellulose-based membrane material. Cellulose is an abundant, renewable, and biodegradable resource that significantly reduces both material cost and environmental impact while maintaining the necessary functional performance for RFB applications
Solution Approach 2:
The chemical composition and structure of the membrane are modified through oxidation and sulfonation of cellulose to achieve parameters comparable to Nafion. The introduction of sulfo groups provides ionic conductivity, while the crosslinked cellulose matrix maintains structural integrity and separation functionality
3Quantity of substance
If high concentration of reactants is used to increase energy density, then volume of storage tanks can be minimized, but membrane stability and prevention of crossover become more difficult
Solution Approach 1:
The membrane structure is optimized at the local level with crosslinked cellulose nanomaterial providing a dense, stable matrix that resists degradation in high-concentration electrolytes. The crosslinking creates a robust three-dimensional network that maintains structural integrity and prevents redox component crossover even under challenging operating 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 membrane enhances mechanical robustness, maintains functionality in aqueous environments, and increases energy density by effectively separating and retaining redox components, addressing the limitations of existing RFB membranes.
Implementation Method 1
oxidation of cellulose fibres by means of sodium metaperiodate (NaIO4) to provide aldehyde groups on surfaces of cellulose nanofibrils (CNF)
Implementation Method 2
sulfonation of some of the aldehyde groups, e.g. by means of sodium metabisulfite (Na2S2O5, which in solution forms the active reactant NaHSO3 which may take part in the sulfonation) to provide sulfo groups on the surfaces of the CNF
Implementation Method 3
at least some of the aldehyde groups have reacted with respective hydroxy groups on the surfaces to form crosslinks
Implementation Method 4
Conventional dialysis membranes allow for size selection but without ion selectivity
Implementation Method 5
an RFB membrane should possess high ionic conductivity for the compensational ions and at the same time preventing crossover of the redox components
Data Source
Figure 1~2
AI summary
The present disclosure relates to a Redox Flow Battery (RFB) 10 comprising a posolyte 3, a negolyte 2, and a membrane 1 made of a crosslinked cellulose nanomaterial, the membrane separating the posolyte and the negolyte from each other. The present disclosure also relates to the membrane and to a method of producing the membrane.