General Motors Co is “almost there” on developing an electric vehicle battery that will last one million miles, a top executive said on Tuesday.

The automaker also is working on next-generation batteries even more advanced than the new Ultium battery that it unveiled in March, according to GM Executive Vice President Doug Parks, who was speaking at an online investor conference.

He did not specify a timeline for introduction of the million-mile battery, but said “multiple teams” at GM are working on such advances as zero-cobalt electrodes, solid state electrolytes and ultra-fast charging.

Current electric vehicle batteries typically last 100,000 to 200,000 miles.