Nickel is used in most EV batteries, just in different levels. The more you use, the better power density you get, the longer the life of the battery, etc. but then you also get more expensive batteries. Because of the cost of Nickel (and Cobolt), some EV manufactures are trying to move away from it. Tesla for example is using LiFePO4 (lithium iron phosphate) batteries in their baseline model vehicles to help reduce cost at the expense of less range and a little more weight.
Battery technology is in constant flux and it's hard to design a EV for "years" around a battery chemistry to then find out that said chemistry is being replaced with a better one. There are plenty of superior battery technologies that could give some insane boost to EVs but they are just too expensive or not safe. Otherwise, we could all drive around on Nuclear Batteries and never need a charging station.