Abstract: Disclosed is a composite fiber including a substrate and a MXene disposed inside the substrate. The substrate contains a polymer and has a fiber shape. Since the MXene content is controlled to be in an optimum range, the mechanical properties, mechanical stability, and oxidation stability of the composite fiber are maximized.

Abstract: MXene fibers and a preparation method thereof are provided. The method for preparation of a MXene fiber comprises preparing a dope solution in which MXene sheets are dispersed in a polar solvent, extruding the dope solution into a coagulating solution to coagulate the extruded dope solution to change into a MXene gel fiber, and drying the MXene gel fiber and converting it into the MXene fiber.

Abstract: A method for recovering performance of a degraded polymer electrolyte fuel cell stack through electrode reversal. In detail, oxide films formed on the surface of platinum of a cathode is removed through an electrode reversal process that creates a potential difference between an anode and the cathode by supplying air to the anode instead of hydrogen and supplying a fuel to the cathode instead of air, thus rapidly recovering the performance of a degraded polymer electrolyte fuel cell stack.

Abstract: A method for accelerating activation of a fuel cell stack may shorten an activation time of the fuel cell stack and reduce the amount of hydrogen used. The method includes a process of applying a high current to the fuel cell stack for a prescribed amount of time and a shutdown maintenance process of pumping hydrogen to an air electrode reaction surface for a prescribed amount of time.

Abstract: A method for activating a fuel cell stack without using an electric load includes chemically adsorbing hydrogen into a catalyst of a cathode. Oxygen remaining in the stack is removed to seal and store the fuel cell stack while maintaining a negative pressure in the fuel cell stack. The method for activating a fuel cell stack does not require an electric load device, and therefore does not increase the number of activation equipment, thereby preventing the total production speed of the fuel cell stack from reducing in response to the stack activation.

Abstract: A method for recovering the performance of a fuel cell stack mounted within a vehicle is provided. A method includes a recovery process of continuously applying a predetermined load using a load device when an air supply is stopped and hydrogen is supplied to a fuel cell stack to output current from the fuel cell stack. Further, protons and electrons generated by hydrogen oxidation reaction at an anode are moved to a cathode, to produce hydrogen at the cathode and simultaneously remove oxide on the catalyst surface of the cathode.

Abstract: A method for activating a stack of a fuel cell is provided. The method includes supplying oxygen and hydrogen to the stack after starting an activation process to change the stack to an open circuit voltage (OCV) state and terminating the supply. Adjacent cells of the stack are electrically connected by a cell voltage sensing terminal board and the adjacent cells are shorted to allow a cell voltage to be 0V. Additionally, oxygen and hydrogen are resupplied to the stack and predetermined current density is applied for a predetermined time is executed. The voltage is again decreased to be 0V by applying current density exceeding the predetermined current density for a time exceeding the predetermined time through the open circuit voltage state to remove oxygen remaining in the stack. Oxygen and hydrogen are resupplied after a silent period has elapsed for a predetermined time after removing the remaining oxygen.

Abstract: A method for activating a stack of a fuel cell is provided. The method includes supplying oxygen and hydrogen to the stack after starting an activation process to change the stack to an open circuit voltage (OCV) state and terminating the supply. Adjacent cells of the stack are electrically connected by a cell voltage sensing terminal board and the adjacent cells are shorted to allow a cell voltage to be 0V. Additionally, oxygen and hydrogen are resupplied to the stack and predetermined current density is applied for a predetermined time is executed. The voltage is again decreased to be 0V by applying current density exceeding the predetermined current density for a time exceeding the predetermined time through the open circuit voltage state to remove oxygen remaining in the stack. Oxygen and hydrogen are resupplied after a silent period has elapsed for a predetermined time after removing the remaining oxygen.

Abstract: Disclosed is an apparatus and method for activating a fuel cell stack, which significantly reduces the time required for activation and the amount of hydrogen used for the activation by employing a vacuum wetting process in a shutdown operation. In particular, a high humidity open circuit voltage operation humidifies the fuel cell stack and operates the fuel cell stack at an open circuit voltage, and a vacuum wetting operation wets the surface of a polymer electrolyte membrane by creating a vacuum atmosphere in the fuel cell stack. The high humidity open circuit voltage operation and the vacuum wetting operation are performed alternately and repeatedly.

Abstract: A method for accelerating activation of a fuel cell stack may shorten an activation time of the fuel cell stack and reduce the amount of hydrogen used. The method includes a process of applying a high current to the fuel cell stack for a prescribed amount of time and a shutdown maintenance process of pumping hydrogen to an air electrode reaction surface for a prescribed amount of time.

Abstract: A method for activating a fuel cell stack without using an electric load includes chemically adsorbing hydrogen into a catalyst of a cathode. Oxygen remaining in the stack is removed to seal and store the fuel cell stack while maintaining a negative pressure in the fuel cell stack. The method for activating a fuel cell stack does not require an electric load device, and therefore does not increase the number of activation equipment, thereby preventing the total production speed of the fuel cell stack from reducing in response to the stack activation.

Abstract: A fuel cell management method includes removing droplets remaining in a fuel cell stack using air supplied to a cathode and hydrogen supplied to an anode. Hydrogen and oxygen remaining are removed in the fuel cell stack by stopping the supply of the hydrogen and the air, and the hydrogen and the oxygen in the fuel cell stack are chemically reacted to remove residual hydrogen and oxygen. Hydrogen is generated in the cathode of the fuel cell stack after removing the residual hydrogen and oxygen. The residual oxygen is additionally removed using the generated hydrogen, the generated hydrogen is absorbed on a surface of a catalyst layer formed on the anode and cathode and accelerating the chemical reaction of hydrogen and air.

Abstract: A fuel cell management method includes removing droplets remaining in a fuel cell stack using air supplied to a cathode and hydrogen supplied to an anode. Hydrogen and oxygen remaining are removed in the fuel cell stack by stopping the supply of the hydrogen and the air, and the hydrogen and the oxygen in the fuel cell stack are chemically reacted to remove residual hydrogen and oxygen. Hydrogen is generated in the cathode of the fuel cell stack after removing the residual hydrogen and oxygen. The residual oxygen is additionally removed using the generated hydrogen, the generated hydrogen is absorbed on a surface of a catalyst layer formed on the anode and cathode and accelerating the chemical reaction of hydrogen and air.

Abstract: A method for recovering the performance of a fuel cell stack mounted within a vehicle is provided. A method includes a recovery process of continuously applying a predetermined load using a load device when an air supply is stopped and hydrogen is supplied to a fuel cell stack to output current from the fuel cell stack. Further, protons and electrons generated by hydrogen oxidation reaction at an anode are moved to a cathode, to produce hydrogen at the cathode and simultaneously remove oxide on the catalyst surface of the cathode.

Abstract: A method for recovering performance of a degraded polymer electrolyte fuel cell stack through electrode reversal. In detail, oxide films formed on the surface of platinum of a cathode is removed through an electrode reversal process that creates a potential difference between an anode and the cathode by supplying air to the anode instead of hydrogen and supplying a fuel to the cathode instead of air, thus rapidly recovering the performance of a degraded polymer electrolyte fuel cell stack.

Abstract: Disclosed is a pre-activation method for a fuel cell stack, which can reduce the amount of hydrogen used and the processing time required during the regular activation process for the fuel cell stack. The disclosure provides, in part, a pre-activation method including: injecting water droplet-containing, humidified hydrogen into a cathode inlet manifold of a fuel cell stack assembled in an assembly process such that the water droplet-containing hydrogen is supplied to a cathode of the fuel cell stack; and sealing and storing the resulting fuel cell stack for a period of time to pre-activate the fuel cell stack.

Abstract: Disclosed is a method for recovering performance of a fuel cell, which can recover the catalytic properties of a cathode in a reusable state by supplying hydrogen to the cathode of a degraded fuel cell stack for a predetermined period of time and storing the fuel cell stack for a predetermined period of time such that an oxide formed on the surface of platinum (Pt) is removed and, at the same time, the platinum is re-precipitated.

Abstract: Disclosed is an apparatus and method for activating a fuel cell stack, which significantly reduces the time required for activation and the amount of hydrogen used for the activation by employing a vacuum wetting process in a shutdown operation. In particular, a high humidity open circuit voltage operation humidifies the fuel cell stack and operates the fuel cell stack at an open circuit voltage, and a vacuum wetting operation wets the surface of a polymer electrolyte membrane by creating a vacuum atmosphere in the fuel cell stack. The high humidity open circuit voltage operation and the vacuum wetting operation are performed alternately and repeatedly.

Abstract: The method of activating a vehicle fuel cell for ensuring maximum performance, improves performance of a polymer electrolyte membrane fuel cell, reduces a hydrogen usage, and has stable performance after manufactured. The method includes: placing a fuel cell in an activation device so as to be activated; changing a humidification state of a humidifier which supplies vapor to the fuel cell and a state of a cooling water; supplying a reactant gas to the fuel cell and maintaining a no-load state; maintaining a load state while changing a flow rate of the vapor and gas supplied to the fuel cell; changing the sate of the fuel cell to the no-load state, and re-supplying the reactant gas to the fuel cell; and comparing data measured when the fuel cell operates in the no-load state and data measured when the fuel cell operates in the load state respectively with a reference value.

Abstract: A separating plate for a fuel cell includes first and second plates, each provided with a hydrogen channel, an oxygen channel, and a coolant channel. The first and second plates are attached to one another to form a main plate such that the first and second hydrogen, oxygen, and coolant channels compose main hydrogen, oxygen, and coolant channels, respectively. The main hydrogen and oxygen channels are fluidly isolated from each other. Distal ends of the main channels each communicate with a manifold through a communication passageway configured to supply hydrogen, oxygen, or coolant to a corresponding one of the main channels.