It doesn't have to however. There is nothing inherent in the mining of lithium that requires CO2 emission, we already have electrical replacements for the industrial vehicles that do the mining in some mines already and its simply a matter of time to replacing the rest. All the solar companies in China run off their own panels and cover their own power needs so the actual emissions are dropping all the time.
Just because an EV being charged emits CO2 today when charged from the grid does not mean that emission wont be reducing over time, it will as the grid power comes increasing from renewable sources. So it is with the production of batteries, PVs and wind turbines a lot of these companies take this as a bootstrapping exercise you have to burn fossil fuels to make the transition but once you do you use the green power to make the next versions with considerably less impact.