  Quantum batteries are energy storage or extract devices in a quantum system.
Here, we present a closed-loop quantum battery by utilizing a closed-loop
three-state quantum system in which the population dynamics depends on the
three control fields and associated phases. We investigate the charging process
of the closed-loop three-level quantum battery. The charging performance is
greatly improved due to existence of the third field in the system to form a
closed-contour interaction. Through selecting an appropriate the third control
field, the maximum average power can be increased, even far beyond the most
ideal maximum power value of non-closed-loop three-level quantum battery
(corresponding to the most powerful charging obtainable with minimum quantum
speed limit time and the maximum charging energy). We study the effect of
global driving-field phase on the charging process and find the maximum
extractable work (`ergotropy') and charging power vary periodically under
different control field, with a period of $2\pi$. Possible experimental
implementation in nitrogen-vacancy spin is discussed.
