Given how old battery-powered electric cars are, I doubt this is actually new.
Experiments with accumulator railcars, as they were originally called, were conducted from around 1890 in Belgium, France, Germany, and Italy. Full implementation of battery trains were undertaken with various degrees of success. In the U.S., railcars of the Edison-Beach type, with nickel-iron batteries were used from 1911. In New Zealand, a battery-electric Edison railcar with a range of 160 km (99 mi) operated from 1926 to 1934 on the 34 km (21 mi) long Little River Branch line. The Drumm nickel-zinc battery was used on four 2-car sets between 1932 and 1946 on the Harcourt Street Line in Ireland. British Railways used lead-acid batteries in a British Rail BEMU from 1958 to 1966 on the 38 mile long Aberdeen to Ballater line in Scotland.