Tesla appears to be moving closer to developing a battery pack that it says will be good for 1 million miles (1.6 million km) of driving.

Forbes reports that on December 26, Tesla in partnership with physicists from Canada’s Dalhousie University, filed a patent for a new lithium-ion battery technology claimed to easily outperform the current lithium-ion batteries used commonly by most current EVs.

Elon Musk said Tesla was working on a 1 million-mile battery pack in April 2019. Such a battery pack likely wouldn’t prove all that important for Tesla’s consumer-oriented vehicles, as the average lifespan for a vehicle in the United States is just 150,000 miles. However, a long-life battery could prove very useful for long-haul trucks that are frequently driven up to 150,000 miles per year.

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The 100 kWh battery used by current Tesla Model S and Model X variants is said to be good for between 1,000 and 2,000 discharge cycles. The new lithium-ion technology described in the patent, if used in the promised 1 million mile battery, may only lose 5 per cent of its capacity after 1,000 discharge cycles and hold 90 per cent of its capacity of 4,000 cycles.

The new battery chemistry described in the patent claims to boost efficiency, energy density, and longevity at reduced costs over current batteries. The new cathode crystal structure and chemical makeup would also mean it is more resistant to damage from charge cycling.

Solid-state batteries are being favored by many car manufacturers as the future of electric vehicles. However, these patents reveal that Tesla and Elon Musk believe lithium-ion batteries still have lots of life left in them.