Nio is often considered to be "the Tesla of China", launching a new model, the ET7, at the company's Nio Day event, as well as announcing a 150kWh solid-state battery.

Several things are interesting about this. Firstly, the timing falls just as Tesla is kicking off its Model Y availability in China - so there's a healthy rivalry here, but it's the new battery that's the most important.

Solid-state batteries are generally seen as the holy grail for future battery tech. They will allow greater energy density and greater stability than the electrolyte-based batteries that are currently used. That means, for the same given space, you can have more power, which in a car translates to greater range.

Nio isn't going to be offering the new battery until 2022, so there's still some time to go, but the new 150kWh battery will offer 620 miles in the new ET7 from a single charge. That's considerable range and a healthy step forward over the current offering.

The interesting thing about Nio's strategy is that the batteries are compatible with a number of models - it will fit the ES8, ES6 and EC6 too, so you'll be able to upgrade your car.

Nio will allow you to buy the car and lease the battery, so it's likely that in the future, you'd be able to shift that lease over to the new battery type instead, swap the battery and enjoy the extra range.

Nio announces 150kWh solid-state EV battery, that's backward compatible photo 2

Of course, this is limited to China, where Nio is planning to expand its Power Swap Station installations up to 500 sites. This is literally a battery swapping station where you can drive in, tap a few buttons and the machine will change the battery in your car for a new power unit.

The thing to keep an eye on - aside from fancy battery swapping machines - will be how fast solid state batteries can be deployed at scale. Most car manufacturers have this battery tech in their sights and we should see quite a lot of progress over the next couple of years.