Method for accelerating activation speed of electrolytic reactor

Abstract

The invention discloses a method for accelerating the activation speed of an electrolysis stack, which comprises the following steps: S1, introducing deionized water to the two sides of hydrogen and oxygen of the electrolysis stack, keeping the temperature of the deionized water to be T0, and keeping the electrode of the electrolysis stack to be fully wet; s2, activating the electrolytic stack by adopting a constant voltage strategy, controlling the average single battery of the electrolytic stack to be V1, controlling the water temperature at the outlet of the electrolytic stack to be T1, and adjusting the hydrogen pressure and the oxygen pressure at the outlet of the electrolytic stack to be P1 and P2 respectively; s3, under the set average single battery V1, along with the increase of the running time, the water temperature at the outlet of the electrolytic stack is gradually increased, the current density is continuously increased, and the hydrogen pressure and the oxygen pressure at the outlet are maintained to be P1 and P2; and S4, stabilizing for a period of time after the water temperature at the outlet of the electrolytic reactor rises to the specified operating temperature Tend until the average single-cell voltage of the electrolytic reactor does not change obviously, and completing the activation operation.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic stacks, and in particular to a method for accelerating the activation speed of an electrolytic stack. Background Art

[0002] An electrolytic stack is an energy conversion device that converts electrical energy directly into chemical energy through an electrocatalytic reaction on an electrode. In order for the electrolytic stack to quickly achieve optimal performance when working, the electrodes in the electrolytic stack need to be activated under given conditions in advance after the electrolytic stack is assembled. The electrolytic stack activation process and mechanism are very complex. The electrodes of the electrolytic stack simultaneously include the following six processes: humidification of the proton exchange membrane, establishment of the electron transmission channel, establishment of the proton transmission channel, establishment of the gas transmission channel, establishment of the water transmission channel, and optimization of the electrode structure. So far, it takes a long time to complete the activation of the electrolytic stack, generally more than ten hours. Commonly used electrolytic stack activation methods mainly include the following processes: 1. Constant current activation; 2. "Constant voltage" + "constant current" combination activation, 3. Water flow temperature control activation, etc. The above activation methods are all carried out under normal pressure conditions for hydrogen and oxygen gas production, and the activation time used is as long as 24 to 48 hours. Even though the improved combined activation can shorten the activation time of the electrolytic stack to 4 to 12 hours, the current activation time of the electrolytic stack still cannot meet the needs of mass production of the electrolytic stack. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention discloses a method for accelerating the activation speed of an electrolytic stack, which specifically comprises the following steps:

[0004] S1: Deionized water is introduced into both sides of the electrolytic stack, and the temperature of the deionized water is controlled to be T0 to keep the electrodes of the electrolytic stack fully moistened;

[0005] S2: Using a constant voltage strategy to activate the electrolytic stack, the average single-cell battery of the electrolytic stack is controlled to be V1, at which time the water temperature at the outlet of the electrolytic stack is T1, and the hydrogen pressure and oxygen pressure at the outlet of the electrolytic stack are adjusted to P1 and P2 respectively;

[0006] S3: Under the set average single-cell V1, as the running time increases, the water temperature at the outlet of the electrolytic stack gradually increases, and the current density continues to increase, maintaining the outlet hydrogen pressure and oxygen pressure at P1 and P2;

[0007] S4: Wait until the outlet water temperature of the electrolytic stack rises to the specified operating temperature T end , stabilize for a period of time until the average single cell voltage of the electrolytic stack does not change significantly, and the activation operation is completed.

[0008] Furthermore, in S1: the deionized water temperature T0 does not exceed 40°C, and T1 and T endNot less than T0 and not more than 90℃, calculated based on the active area of ​​a single electrolytic cell, water flow range 0.5 to 5 mL min -1 cm -2 , the water flow is maintained for 3 to 30 minutes.

[0009] Furthermore, the average voltage V1 of a single cell of the electrolytic stack in S2 ranges from 1.7 to 1.9 V, and the maximum single cell voltage limit value V max Not exceeding 1.95V.

[0010] Furthermore, the hydrogen pressure and oxygen pressure at the outlet of the electrolytic stack in S3 are respectively at P1 and P2, ranging from 0.2 to 1 MPa, and are maintained for 3 to 30 minutes.

[0011] Furthermore, in S4, the specified operating temperature range of the electrolytic stack is 50 to 90° C., and at the specified operating temperature, the average single-cell voltage change value of the electrolytic stack is no more than 5 mV / min, and the activation process is completed.

[0012] Due to the adoption of the above technical scheme, the present invention provides a method for accelerating the activation speed of an electrolytic stack. This method controls the upper limit of the voltage of a single cell of the electrolytic stack and does not limit the current value of the electrolytic stack. Under the premise of ensuring the safety of the electrolytic stack, the restriction on the electrolytic current is relaxed to the greatest extent, so that the activation time of the electrolytic stack is greatly shortened, the activation process of a single electrolytic stack can be completed quickly, and the speed of the electrolytic stack leaving the factory is greatly improved. In addition, this method gradually increases the water temperature through a constant voltage strategy, and does not require additional auxiliary heating devices. The entire activation process can be completed only by a normal test bench. The electrolytic cell is gradually operated at a high current density, so that the water generated by the reaction can quickly humidify the membrane electrode, eliminate unstable catalysts on the electrode surface, oxidize impurities on the electrode surface, and realize rapid activation of the membrane electrode. The electrode is made to quickly form a stable gas and electron transmission channel to achieve accelerated activation of the electrolytic stack.

[0013] The present invention controls the hydrogen and oxygen pressures at the outlet of the electrolytic stack and appropriately increases the hydrogen and oxygen production pressures, which can significantly compress the gas volume inside the electrolytic stack, and can effectively reduce the scouring of electrodes and catalysts whose microstructures are not yet stable due to bubble generation and breakage during the activation of the electrolytic stack, thereby effectively protecting the electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1A flow chart of the method for accelerating the activation rate of an electrolytic stack according to the present invention;

[0016] Figure 2 Comparison of polarization curves of electrolytic stacks measured under the conditions of Example 1;

[0017] Figure 3 Comparison of polarization curves of electrolytic stacks measured under the conditions of Example 2;

[0018] Figure 4 Comparison of the polarization curves of the electrolytic stack measured under the conditions of Comparative Example 1. DETAILED DESCRIPTION

[0019] In order to make the technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention:

[0020] like Figure 1 A method for accelerating the activation speed of an electrolytic stack is shown, in which the unstable catalyst on the electrode surface is firstly eliminated by pre-activation, and the impurities on the electrode surface are oxidized to achieve rapid activation of the membrane electrode. Then, the water generated by the reaction can be rapidly humidified to the membrane electrode by a constant voltage variable current activation method, so as to achieve rapid humidification of the proton exchange membrane and the catalyst layer resin; by controlling the cross operation of the electrolytic stack at high and low current densities, the electrode can quickly form a stable gas and electron transmission channel, so as to achieve accelerated activation of the electrolytic stack and obtain stable electrolytic stack performance.

[0021] Example 1

[0022] Under the optimal operating conditions of this technical solution, the voltage of the electrolytic stack is kept constant at 1.85V for activation operation, and the hydrogen and oxygen pressures at the outlet of the electrolytic stack are simultaneously at 0.5MPa, which can achieve rapid activation within 2 hours. Figure 2 shown.

[0023] Activation operation:

[0024] Step (1) Add 25°C deionized water to both sides of the electrolytic stack at a rate of 2 mL / min. -1 cm -2 , continue for 10 minutes to fully wet the electrolytic stack electrodes.

[0025] Step (2): Then, a constant voltage strategy is adopted to activate the electrolytic stack, and the average voltage of a single cell of the electrolytic stack is controlled to be 1.85 V. At this time, the maximum voltage of a single cell of the electrolytic stack is 1.87 V, and the outlet water temperature is 25° C. The hydrogen and oxygen pressures at the outlet of the electrolytic stack are adjusted to 0.5 MPa at the same time, and maintained for 10 minutes;

[0026] Under the average single-cell voltage of 1.85V set in step (3), as the operation time increases, the water temperature at the outlet of the electrolytic stack will gradually increase, and the current density will continue to increase, maintaining the outlet hydrogen and oxygen pressures at 0.5MPa at the same time for 1 hour;

[0027] Step (4) When the water temperature at the outlet of the electrolytic stack rises to the specified operating temperature of 60° C. and stabilizes for 30 minutes, and the average single-cell voltage change rate of the electrolytic stack is 2 mV / min, the activation operation is completed.

[0028] When the activation time is 1 hour, 2 hours and 3 hours respectively, polarization curve test of the electrolytic stack is carried out.

[0029] Example 2

[0030] This technical solution is adopted, but the operating conditions are not optimal. The voltage of the single cell of the electrolytic stack is kept constant at 1.65V for activation operation, and the hydrogen and oxygen pressures at the outlet of the electrolytic stack are at normal pressure at the same time. Activation can be achieved in 3 hours. Figure 2 shown.

[0031] Step (1): Add 25°C deionized water to both sides of the electrolytic stack at a rate of 2 mL / min. -1 cm -2 , continue for 10 minutes to fully wet the electrolytic stack electrodes.

[0032] Step (2): Then, a constant voltage strategy is adopted to activate the electrolytic stack, and the average voltage of a single cell of the electrolytic stack is controlled to be 1.65V. At this time, the maximum voltage of a single cell of the electrolytic stack is 1.66V, and the outlet water temperature is 25°C. The hydrogen and oxygen pressures at the outlet of the electrolytic stack are adjusted to be at normal pressure at the same time, and maintained for 10 minutes;

[0033] Step (3): Under the set average single-cell voltage of 1.65V, as the operation time increases, the water temperature at the outlet of the electrolytic stack will gradually increase, and the current density will continue to increase, while the outlet hydrogen and oxygen pressures are maintained at normal pressure for 1 hour;

[0034] Step (4): When the water temperature at the outlet of the electrolytic stack rises to the specified operating temperature of 60°C and stabilizes for 30 minutes, and the average single cell voltage change rate of the electrolytic stack is 2mV / min, the activation operation is completed.

[0035] When the activation time is 1 hour, 2 hours, 3 hours and 5 hours respectively, polarization curve test of the electrolytic stack is carried out.

[0036] Comparative Example 1

[0037] The electrolytic stack was activated by constant current method. After 5 hours of activation, the performance was still not stable and the electrolytic stack was not fully activated. Figure 4 shown.

[0038] Activation operation:

[0039] 1. Add 25℃ deionized water to both sides of the electrolytic stack at a rate of 2mL / min. -1 cm -2 , continue for 10 minutes to fully wet the electrolytic stack electrodes.

[0040] 2. Then, the electrolytic stack activation operation was carried out using a constant current strategy, and the electrolytic stack current density was controlled to be 500 mA / cm 2 At this time, the water temperature at the outlet of the electrolytic stack is 26℃.

[0041] 3. When the water temperature at the outlet of the electrolytic stack rises to the specified operating temperature of 60°C and stabilizes for 30 minutes, and the average single cell voltage change rate of the electrolytic stack is 2mV / min, the activation operation is completed.

[0042] When the activation time is 1 hour, 2 hours, 3 hours, 5 hours and 7 hours respectively, polarization curve test of the electrolytic stack is carried out.

[0043] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for accelerating the activation rate of an electrolytic stack, characterized in that include: S1: Deionized water is introduced into both sides of the electrolytic stack, and the temperature of the deionized water is controlled to be T0 to keep the electrodes of the electrolytic stack fully moistened; S2: Using a constant voltage strategy to activate the electrolytic stack, the average single-cell battery of the electrolytic stack is controlled to be V1, at which time the water temperature at the outlet of the electrolytic stack is T1, and the hydrogen pressure and oxygen pressure at the outlet of the electrolytic stack are adjusted to P1 and P2 respectively; S3: Under the set average single-cell V1, as the running time increases, the water temperature at the outlet of the electrolysis stack gradually increases, and the current density continues to increase, maintaining the outlet hydrogen pressure and oxygen pressure at P1 and P2; S4: Wait until the outlet water temperature of the electrolytic stack rises to the specified operating temperature T end , stabilize for a period of time until the average single cell voltage of the electrolytic stack does not change significantly, and the activation operation is completed.

2. The method for accelerating the activation speed of an electrolytic stack according to claim 1, characterized in that: In S1: the deionized water temperature T0 does not exceed 40°C, and controls T1, T end Not less than T0 and not more than 90℃, calculated based on the active area of ​​a single electrolytic cell, water flow range 0.5 to 5 mL min -1 cm -2 , the water flow is maintained for 3 to 30 minutes.

3. The method for accelerating the activation speed of an electrolytic stack according to claim 1, characterized in that: The average voltage V1 of a single cell in the electrolytic stack in S2 ranges from 1.7 to 1.9 V, and the maximum single cell voltage limit is V max Not exceeding 1.95V.

4. The method for accelerating the activation speed of an electrolytic stack according to claim 1, characterized in that: In S3, the hydrogen pressure and oxygen pressure at the outlet of the electrolytic stack are respectively P1 and P2, ranging from 0.2 to 1 MPa, and the maintenance time is 3 to 30 minutes.

5. The method for accelerating the activation speed of an electrolytic stack according to claim 1, characterized in that: In S4, the specified operating temperature range of the electrolytic stack is 50 to 90° C., and at the specified operating temperature, the average single cell voltage change value of the electrolytic stack is no more than 5 mV / min, and the activation process is completed.

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