  Superconductivity is successfully induced by utilizing a battery-like
reaction found in a typical Li-ion battery. Excess Fe in FeTe0.8S0.2 is
electrochemically de-intercalated by applying a voltage in a citric acid
solution. The superconducting properties improve with an increase in the
applied voltage up to 1.5 V. This result suggests that an electrochemical
reaction can be used as a novel method to develop new superconducting
materials.
