Sodium-ion batteries and battery swapping stations

[whole diary]

[grahame]

From The BBC^» (British Broadcasting Corporation - home page)

The sheer number of two-wheelers in Asia paves a promising pathway to achieving economies of scale. In China alone, around 55 million electric two-wheelers were sold in 2023 – nearly six times the number of all pure, hybrid and fuel-cell electric cars combined sold in the country that year – according to Shanghai-based consultancy iResearch.

Scale production was the goal of Yadea. Zhou said at the talk show that the firm was seeking to bring sodium batteries to tens of millions of ordinary commuters by not only fitting them into two-wheelers, but also building a charging ecosystem to enable people to use these models without stress.

To test the waters, in 2024 Yadea began a pilot programme with 150,000 food delivery couriers working in Shenzhen, a mega city of 17.8 million people in southern China, reported Shenzhen News. The goal was to enable them to hand in a spent Yadea sodium-ion batteries at its partners' battery-swapping stations in exchange for a fully charged one within 30 seconds, Yadea said.

The story is about scooters and road vehicles, but I do wonder about local battery trains exchanging a spent cell for a fully charged one in 30 seconds at each intermediate station

[Oxonhutch]

In my experience, 30 seconds in the railway world is faster than the speed of light

[grahame]

In my experience, 30 seconds in the railway world is faster than the speed of light

Indeed - a battery change at an intermediate stop that's this quick would be faster that the dropping off and picking up of passengers.    Of course, the need for battery changes quite frequently would mean there's a need for exchanges at places like Devizes Gateway, Somerton/Langport, Wellington and Cullompton.

[broadgage]

I see no need for trains to have frequent battery exchanges, and probably no need for any exchanging of batteries in normal service.
Presently available lithium batteries  can give a battery train a useful range of hundreds of miles, no one is going to adopt the new and relatively untried sodium batteries unless these can give a significant improvement on this range.

Physically swapping batteries sounds like a lot of moving parts and extra failure points.

Fast charging the batteries in situ sounds a lot more sensible, and can be automated. Should be simple and reliable, with sufficient battery capacity so as to permit of at least two consecutive fast charges at stations being missed without any reduction in performance.