Among these, all-solid-state lithium micro-battery may be one of the promising power sources because lithium is the lightest metal and has a low potential to provide high energy density.

It says it has developed a micro-turbine engine to act as an on-board charger and a high-density battery that can power a vehicle for about 60-80 km (35-50 miles) on one charge.

It says it has developed a micro-turbine engine to act as an on-board charger and a high - density battery that can power a vehicle for about 60-80 km (35-50 miles) on one charge.