Engineers at Toyota Motor Corp. say they have tamed volatile lithium-ion battery technology, and can now safely pack more power at no significant extra cost, giving the automaker the option to enter the growing all-electric car market.

While rivals including Tesla Motors and Nissan Motor Co. began adopting Li-ion battery technology nearly a decade ago, Toyota has largely held back due to concerns about cost, size and safety.

The batteries can be unstable and have been blamed for incendiary Samsung smartphones and smoking Boeing 787 Dreamliner planes.