Abstract: Electrochemical cells that include resistor switch assemblies that can operate according to temperature and batteries and power systems including such cells are disclosed.

Abstract: A battery with three types of terminals is disclosed. The terminals include at least one negative terminal, at least one positive terminal, and at least one sensor terminal. The negative and positive terminals carry current during battery operation, while the sensor terminal is used to sense, communicate and/or control certain aspects of the battery. The sensor terminal can also be connected to external electronic units for sensing, communication and control of the battery usage.

Abstract: Electrochemical cells that include resistor switch assemblies that can operate according to temperature and batteries and power systems including such cells are disclosed.

Abstract: A method for determining when to operate a voltage recovery process for recovering a reversible voltage loss of a fuel cell stack in a fuel cell system. The method includes estimating an irreversible voltage loss of the fuel cell and an actual voltage of the fuel cell stack, and determining whether a difference between the estimated irreversible voltage loss and the estimated actual voltage exceed a threshold, and if so, the voltage recovery process is performed.

Abstract: A method for determining the health of the membranes in a fuel cell stack. The total parasitic current of the fuel cells in the stack is determined. From the total parasitic current, the shorting resistance and the cross-over parasitic current are determined. The health of the membranes is then determined from the cross-over parasitic current and the shorting resistance.

Abstract: A battery with three types of terminals is disclosed. The terminals include at least one negative terminal, at least one positive terminal, and at least one sensor terminal. The negative and positive terminals carry current during battery operation, while the sensor terminal is used to sense, communicate and/or control certain aspects of the battery. The sensor terminal can also be connected to external electronic units for sensing, communication and control of the battery usage.

Abstract: A battery system is disclosed that can internally heat a battery by consuming minimal battery energy and with short heating times.

Abstract: A graded electrode is described. The graded electrode includes a substrate; and at least two electrode layers on the substrate forming a combined electrode layer, a composition of the at least two electrode layers being different, the combined electrode layer having an average level of the property that changes across the substrate. Fuel cells using graded electrodes and methods of making graded electrodes are also described.

Abstract: A method for determining the health of fuel cells in a fuel cell stack. The method includes maintaining a constant flow of hydrogen to the anode side of the fuel cell stack, shutting off a flow of air to a cathode side of the fuel cell stack when a predetermined concentration of hydrogen in the anode side has been achieved, and identifying a catalyst surface area and a catalyst support surface area for catalyst layers in the fuel cell stack. The method also includes determining the total parasitic current of the fuel cell stack to determine a cross-over parasitic current and a shorting resistance of the fuel cell stack. The method further includes calculating the catalyst surface area and the catalyst support surface area of the catalyst layers and comparing the difference between the identified catalyst surface area and the calculated catalyst surface area to estimate the change in the catalyst surface area.

Abstract: A method for determining when to operate a voltage recovery process for recovering a reversible voltage loss of a fuel cell stack in a fuel cell system. The method includes estimating an irreversible voltage loss of the fuel cell and an actual voltage of the fuel cell stack, and determining whether a difference between the estimated irreversible voltage loss and the estimated actual voltage exceed a threshold, and if so, the voltage recovery process is performed.

Abstract: A method for determining the health of fuel cells in a fuel cell stack. The method includes maintaining a constant flow of hydrogen to the anode side of the fuel cell stack, shutting off a flow of air to a cathode side of the fuel cell stack when a predetermined concentration of hydrogen in the anode side has been achieved, and identifying a catalyst surface area and a catalyst support surface area for catalyst layers in the fuel cell stack. The method also includes determining the total parasitic current of the fuel cell stack to determine a cross-over parasitic current and a shorting resistance of the fuel cell stack. The method further includes calculating the catalyst surface area and the catalyst support surface area of the catalyst layers and comparing the difference between the identified catalyst surface area and the calculated catalyst surface area to estimate the change in the catalyst surface area.

Abstract: A method for determining the health of the membranes in a fuel cell stack. The total parasitic current of the fuel cells in the stack is determined. From the total parasitic current, the shorting resistance and the cross-over parasitic current are determined. The health of the membranes is then determined from the cross-over parasitic current and the shorting resistance.

Abstract: A graded electrode is described. The graded electrode includes a substrate; and at least two electrode layers on the substrate forming a combined electrode layer, a composition of the at least two electrode layers being different, the combined electrode layer having an average level of the property that changes across the substrate. Fuel cells using graded electrodes and methods of making graded electrodes are also described.