CN-121983153-A - Electrochemical dynamics correction calculation method for hydrogen production by water electrolysis of proton exchange membrane

CN121983153ACN 121983153 ACN121983153 ACN 121983153ACN-121983153-A

Abstract

The invention discloses a calculation method for electrochemical dynamics correction of proton exchange membrane water electrolysis hydrogen production, which comprises the steps of S1, model assumption, S2, construction of an electrochemical model, S2.1, solving of two charge balance equations in an electron conduction domain and an electrolyte domain, completion of coupling calculation of potential distribution and electrochemical dynamics, S2.2, introduction of volume fractions and stoichiometric coefficients of all components into the balance potential equation and Butler-Volmer equation, completion of equation correction, establishment of a corrected PEMWE three-dimensional simulation model, and S3, verification of accuracy of the corrected PEMWE three-dimensional simulation model and calculation method. The electrochemical dynamics correction calculation method for hydrogen production by water electrolysis of the proton exchange membrane provided by the invention corrects the electrochemical dynamics calculation of the electrolytic cell and solves the problem that the electrochemical reaction rate of the electrolytic cell is influenced by the concentration of the reactant in the actual calculation.

Inventors

SU CHAO
TAN KEDI
ZHAO WEI
HAN SHENGHU
ZHANG NAIQIANG
KONG YANQIANG

Assignees

陕西氢能绿源科技有限公司
华北电力大学

Dates

Publication Date: 20260505
Application Date: 20260123

Claims (8)

1. The electrochemical dynamics correction calculation method for the hydrogen production by the water electrolysis of the proton exchange membrane is characterized by comprising the following steps of: S1, model assumption, namely reasonable assumption and simplification are made during model building; S2, constructing an electrochemical model: s2.1, solving two charge balance equations in an electron conduction domain and an electrolyte domain to finish coupling calculation of potential distribution and electrochemical dynamics; S2.2, introducing the volume fraction S i and the stoichiometric coefficient v i of each component into a balance potential equation and a Butler-Volmer equation, finishing the correction of the Butler-Volmer equation, and establishing a corrected PEMWE three-dimensional simulation model; And S3, verifying the accuracy of the corrected PEMWE three-dimensional simulation model and the calculation method, namely building a PEMWE single cell test system, and verifying the accuracy of the built electrochemical model.
2. The method for calculating the electrochemical kinetics modification of hydrogen production by water electrolysis in a proton exchange membrane according to claim 1, wherein the assumption made in S1 is specifically as follows: the water in the electrolytic cell exists in a liquid state, and the phase change process of the water is ignored; All gases are considered to be ideal gases that are not compressible; Neglecting cross permeation of hydrogen and oxygen in the proton exchange membrane; The anode catalytic layer, the cathode catalytic layer, the anode porous transport layer, the cathode porous transport layer and the PEM are all homogeneous structures and have isotropy; the contact resistance and contact thermal resistance between all adjacent elements are ignored.
3. The method for calculating the electrochemical kinetics modification of the hydrogen production by the water electrolysis of the proton exchange membrane according to claim 1, wherein the specific method of S2.1 is as follows: The solid phase potential and the electrolyte potential in the water electrolyzed by the proton exchange membrane are calculated according to the following equation: (1) (2) Wherein delta s is solid phase conductivity, S/m; i R i is a local current source, A/m 3 ;δ m is proton conductivity, S/m is a function of temperature and moisture content λ, where λ is defined as the ratio of the number of water molecules to the number of band-point junctions: (3) The equilibrium potential E eq (V) is defined by the Nernst equation: (4) Wherein n is the number of electrons participating in the electrode reaction, F is Faraday constant, the value is 96485C/mol, R is general gas constant, T is the temperature of each point in the calculation domain, the unit is K, and C R and C O are dimensionless expressions for describing the concentration dependence of oxidized and reduced substances in the reaction; The current density of the electrodes and the cathodes in the water electrolyzed by the proton exchange membrane is related to the local concentration of each substance participating in the reaction on the surface of the electrodes, and is defined as: (5) Where i 0 is the exchange current density in a/m 2 ;α a and α c is the anode and cathode charge transfer coefficients, respectively, where α a +α c =n, η is the activation overpotential in V.
4. A method for calculating electrochemical kinetics modification for water electrolysis hydrogen production by proton exchange membrane according to claim 3, wherein in the above formula (4), the reference equilibrium potential Eeq, ref (T) of each electrode reaction is calculated from the standard free energy Δh and the reaction entropy Δs: (6)。
5. A method of calculating electrochemical kinetics modification for hydrogen production by water electrolysis in a proton exchange membrane as claimed in claim 3, wherein the activation overpotential η is defined as: (7) Considering the electron transfer process, the electrochemical reaction equation is expressed as: (8) where v i is the stoichiometric coefficient of the reactant species.
6. The method for calculating the electrochemical kinetics modification of the hydrogen production by the water electrolysis of the proton exchange membrane according to claim 5, wherein the specific method of S2.2 is as follows: Introducing the volume fractions of the components s i and the stoichiometric coefficient v i into the equilibrium potential equation and the Butler-Volmer equation, using s i νi to represent the introduction of C i into equations (4) and (5), yields the following expression: (9) (10) (11) (12)。
7. The method for calculating electrochemical kinetics correction of water electrolysis hydrogen production by proton exchange membrane according to claim 1, wherein the PEMWE single cell test system in S3 adopts commercial CCM, specifically IrO 2 2.2 mg/cm 2 ,Pt/C 1.2 mg/cm 2 , nafion 115 and active area of 6.25 cm 2 , anode and cathode sides PTLs respectively adopt titanium felt and Toray 060 carbon paper, the thickness of the titanium felt is 250 μm, the porosity is 65%, the thickness of the Toray 060 carbon paper is 192 μm, the porosity is 78%, a cathode and an anode adopt titanium plates with parallel flow channels, the outer sides of the flow channel plates are clamped by 2 stainless steel end plates, and are tightly screwed by 8 evenly distributed M6 bolts with torque of 5N.m, and in order to prevent leakage, interlayer sealing is carried out by adopting PTFE; The PEMWE single cell testing system comprises a direct current power supply, a water tank, a peristaltic pump, an electrolytic cell, an electric heater and a connecting pipeline.
8. The method for calculating the electrochemical kinetics modification of the hydrogen production by the water electrolysis of the proton exchange membrane according to claim 7, wherein the specific method for the test process in the step S3 is as follows: The method comprises the steps of supplying current to an electrolytic cell through a direct current power supply in a test process, regulating the power of an electric heater through PID control to ensure constant water temperature at an inlet of the electrolytic cell, supplying deionized water to an anode of the electrolytic cell through a peristaltic pump at a flow rate of 15 mL/min, discharging generated H 2 and O 2 into an external environment through a connecting pipeline, and returning carried outlet water to a water tank through a separator to complete a cycle; in order to remove residual impurities introduced in the CCM manufacturing process, an electrolytic cell activation process is carried out before each experimental test, and the whole activation process lasts for 12 hours; In the experimental process, the electrolysis current density is changed by adjusting a direct current power supply, more than 180 s times of stable operation of working conditions are needed for each data acquisition, the current and the voltage of the last 60 seconds are recorded, and all the tests are carried out under the conditions that the water inlet temperature is 65 ℃ and the back pressure is atmospheric pressure.

Description

Electrochemical dynamics correction calculation method for hydrogen production by water electrolysis of proton exchange membrane Technical Field The invention belongs to the technical field of PEM (proton exchange membrane) electrolytic tanks, and particularly relates to a calculation method for electrochemical dynamics correction of hydrogen production by water electrolysis through a proton exchange membrane. Background Proton Exchange Membrane Water Electrolysis (PEMWE) technology has the advantages of high current density, high energy conversion efficiency, good renewable energy adaptability and the like, and becomes a leading research direction in the field of large-scale energy storage. However, the PEMWE needs to adopt an expensive noble metal catalyst and is served in severe environments with high current density (more than 1A/cm 2), strong acidity and non-uniform distribution of multi-component gas and heat electricity, so that the investment cost is high, the electrode performance is fast to decay, and the commercialization process is severely restricted. Thus, reducing the cost and ensuring long-term stable operation of the electrolyzer is the primary task of current research. For a long time, PEMWE has been studied mainly on the design and regulation of material layers, ignoring the process of heat and mass transfer inside the membrane electrode. In the past work, researchers obtain the parameter change trend of the working temperature of the electrolytic cell, the temperature of water in and out and the interlayer local temperature under different working conditions through a plurality of experimental methods. However, due to the complexity of CCM process and structure, on-line measurement of the micro-area temperature distribution of the membrane electrode still faces a great challenge. In addition, the related research on the current experimental level is mainly focused on the operation range of low current density (0-2A/cm 2), but in order to adapt to the large-scale preparation and commercialization requirements of hydrogen, the efficient and stable operation of PEMWE with high current density (more than 2.0A/cm 2) is a great development trend of PEMWE in the future. However, under high current density operating conditions, the CCM region involves heterogeneous electrochemical reactions, mass transfer mechanisms such as heat transfer, convection, gas diffusion, and the like, exhibiting distinct thermal coupling characteristics. Therefore, there is an urgent need to intensively study thermal coupling characteristics of the PEMWE membrane electrode area at a high current density. Although the existing experimental method has important significance in researching the internal temperature change characteristics of the electrolytic cell under different operation conditions, the internal area thermal coupling characteristics of the complex structure of the membrane electrode are difficult to quantitatively describe. In contrast, in the finite element method and the finite volume method developed in recent years, the PEMWE three-dimensional model is discretized in time and space, and the distribution rule of key physical quantities such as electrochemical reaction, gas-liquid two-phase flow and heat transfer can be revealed based on solving partial differential equations. Although many three-dimensional, two-phase, steady-state, multi-physical-field PEMWE simulation models have been developed for calculating the reaction and heat and mass transfer processes inside the electrolytic cell, these models often directly reference relatively perfect fuel cell models to construct electrode reaction kinetics, and directly modify Butler-Volmer equations through liquid water saturation indexes, so that it is difficult to reveal the mechanism of action between the gas-liquid transfer and electrochemical reaction characteristics of the PEMWE electrode surface under real service conditions. Disclosure of Invention The invention aims to provide a proton exchange membrane water electrolysis hydrogen production electrochemical dynamics correction calculation method, which creatively develops a 3D, two-phase and non-isothermal multi-physical-field theoretical analysis model based on gas phase volume fraction correction on the basis of classical electrochemical reaction dynamics theory, reveals the influence rule of heat transfer, mass transfer and electrode electrochemical reaction processes on the thermal coupling characteristics of the electrode surface, corrects electrochemical dynamics calculation of an electrolytic cell, and solves the problem that the electrochemical reaction rate of the electrolytic cell is influenced by the concentration of a reactant in the actual calculation. The technical scheme adopted by the invention is that the electrochemical dynamics correction calculation method for hydrogen production by water electrolysis of the proton exchange membrane comprises the following steps: S1, model as