GB/T 43080.3-2023 Ion conductive membrane for Vanadium flow battery - Technical conditions and test methods
1 Scope
This document specifies the terms and definitions, sampling methods and general conditions, technical requirements, and test methods for the thickness uniformity, areal resistance, conductivity, ion exchange capacity, tensile properties, water uptake, dimensional change rate, vanadium ion diffusion coefficient, ion permeation selectivity and oxidation resistance of ion conductive membrane for vanadium flow battery.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 601-2016 Chemical reagent - Preparations of reference titration solutions
GB/T 1040.3-2006 Plastics - Determination of tensile properties - Part 3: Test conditions for films and sheets
GB/T 1462-2005 Test methods for water absorption of fiber reinforced plastics
GB/T 6672-2001 Plastics film and sheeting - Determination of thickness by mechanical scanning
GB/T 20042.3 Proton exchange membrane fuel cell - Part 3: Test method for proton exchange membrane
GB/T 20103 Technical terms for membrane separation
GB/T 29840-2013 Vanadium flow battery - Terminology
3 Terms and definitions
For the purpose of this document, the terms and definitions given in GB/T 29840-2013 and GB/T 20042.3 and the following apply.
3.1
ion conductive membrane
membrane that separates the positive and negative electrolytes and selectively conducts ions
[Source: GB/T 29840-2013, 2.2, modified]
Note: Both ion exchange membranes and porous ion conductive membranes belong to ion conductive membranes, and their mechanisms of conducting ions are the ion exchange mechanism and sieving mechanism respectively.
3.2
ion exchange membrane
ion conductive membrane containing ion exchange groups, which may selectively permeate ions
3.3
porous ion conductive membrane
ion conductive membrane for sieving and conducting hydrogen ions and vanadium ions by nano-aperture
3.4
membrane resistance
resistance in the membrane thickness direction at given temperature and solution composition, expressed in Ω
3.5
effective area
geometric area of an ion conductive membrane realizing ion conduction, perpendicular to the current direction, expressed in cm2
3.6
membrane area resistance
product of the resistance and the effective area of the ion conductive membrane during measurement, expressed in Ω·cm2
3.7
membrane conductivity
capability of a membrane to pass ions, which is equal to the ratio of membrane thickness to membrane area resistance, expressed in S/cm
3.8
dry membrane
membrane containing no free water within as opposed to wet membrane
Note: It is typically obtained by drying an ion conductive membrane in an oven at 105℃~110℃ for a certain period of time until it reaches a constant weight as weighed by a balance.
3.9
ion exchange capacity (IEC)
number of moles of ion exchange groups per gram of dry ion exchange membrane, expressed in mol/g
3.10
water uptake
rate of mass change of a dry membrane before and after water absorption at a specified temperature and humidity, expressed in percentage (%)
3.11
dimensional change rate
dimensional change rate in the transverse, machine and thickness directions of a membrane after being immersed in a specific solvent for a certain time at a specified temperature and humidity, expressed in percentage (%)
3.12
ion diffusion coefficient
quantity of ions permeating through an ion conductive membrane under given conditions, expressed in cm2/s
3.13
ion permeation selectivity
capability of an ion conductive membrane to selectively allow permeation of different ions, quantified as the ratio of ion diffusion coefficients for different ions measured under given conditions
4 Technical requirements
4.1 General
In a vanadium battery, the ion conductive membrane divides the battery into two half-cells, separating the electrolytes at the cathode and the anode, and forming a current loop by transferring ions. An ideal ion conductive membrane shall have the following properties:
——Low dimensional change rate;
——High membrane conductivity and ion permeation selectivity;
——Low vanadium ion diffusion coefficient;
——Robust chemical stability.
4.2 Indicator requirements
The technical indicators of ion conductive membrane shall be as specified in Table 1.
Foreword II
1 Scope
2 Normative references
3 Terms and definitions
4 Technical requirements
4.1 General
4.2 Indicator requirements
5 Test methods
5.1 Sampling method and general conditions
5.2 Accuracy requirements for instruments
5.3 Thickness uniformity
5.4 Water uptake
5.5 Dimensional change rate
5.6 Tensile properties
5.7 Conductivity and membrane area resistance
5.8 Ion exchange capacity (IEC)
5.9 Vanadium ion diffusion properties
5.10 Ion permeation selectivity
5.11 Oxidation resistance
Annex A (Normative) Pretreatment method for ion conductive membrane
Annex B (Normative) Calibration of 0.1mol/L NaOH standard solution
Annex C (Informative) Preparation method before ion permeation selectivity coefficient test
Annex D (Informative) Derivation method for equation for ion diffusion coefficient
