Xiaomi, the smartphone vendor that has become one of Tesla’s biggest challengers in mainland China after entering the electric vehicle (EV) market, has doubled down on research and development to combat a slowdown in domestic sales. The Beijing-based tech giant announced on Thursday it would assemble and sell models under a new sport-utility vehicle (SUV) line known as Sky Nomad, a product range analysts said would be likely to include extended-range battery technology to lure consumers away...