  Spin valves based on materials in which the spin-flip is suppressed by the
spatial separation of charge carriers, while maintaining electric neutrality in
the valve volume, are considered. The possibility of using these valves as
electric batteries is discussed. It is shown that if the potential difference
across the valve is controlled, incommensurability effects such as the "devil's
staircase" may be expected, which are associated with the Coulomb interaction
and redistribution of electrons occurring while the battery is charged and
discharged. The effects of the emergence and vanishing of spontaneous spin
polarization of conduction electrons with a change in the Fermi level in the
valve are predicted. Such spin valves can also be used in implementing
spintronic memory cells, supercapacitors, and similar devices.
