Lithium-ion battery technology has made impressive gains over the years. Today’s cells are cheaper than they used to be, but lithium-ion still leaves a lot to be desired in terms of energy density compared to liquid hydrocarbon fuels. Which means that putting enough of them in a car to give it acceptable range adds a lot of mass and volume. Which is where SSD batteries go.
In a traditional battery, a pair of electrodes are immersed in an electrolyte solution and this liquid electrolyte allows ions to move from one electrode to another. But liquid electrolytes can leak, and that’s not a great thing, whether the material is highly corrosive, like in a lead-acid battery, or highly flammable, like in a lithium-ion battery. So researchers around the world are experimenting with batteries that use solid electrolyte instead, with particular emphasis on their use in electric vehicles.
And now it looks like it’s a technology that’s ready for deployment, as Mercedes-Benz has just announced that its new eCitaro and eCitaro G city buses will be available with roof-mounted solid batteries developed in collaboration with the Canadian power company. Hydro Quebec.
Although the details are still quite limited at the moment, Mercedes-Benz says the solid-state package has a 25% higher energy density than even the most advanced lithium-ion chemistry. He also says that the semiconductor battery has a much better service life than the lithium-ion one and guarantees these batteries for 10 years or an energy capacity of 280MWh. When configured with a total of 441kWh on board (consisting of seven 63kWh packages), the eCitaro G has a range of up to 220 miles (220 km) in favorable conditions or 105 miles (170 km) in winter depth with the bus heaters running.
However, these semiconductor batteries are not perfect. In particular, they are not able to charge quickly at speeds comparable to lithium-ion, which is why Mercedes-Benz also offers the bus an optional lithium-ion package, which can instead be charged at 150kW or even 300kW. This uses nickel-manganese-cobalt chemistry and is available in 33kWh units that can be combined to produce a busbar up to 396kWh in total.
Image of a list from Mercedes-Benz