One Small Step

Another possibility is to use aluminum-air batteries. Any lunar base
is likely to develop mining/refinig capability which would necessarily
produce the aluminum and oxygen these batteries run on. The batteries
are refreshed by replacing/recycling oxidized aluminum which would
dovetail well with the refining activities. If vapor phase separation
is used for refining using concentrated sunlight, no photovoltaics are
required at all.
Steve Mickler