Toyota is the world's largest carmaker with annual sales volume of over 8 million units. The company has Tier 1 affiliates such as Aisin, Denso, and Toyoda Industries. The company is late to the EV business, originally focusing on hybrids. At the end of 2021, it announced that US$35B will invest in EVs and will work mainly with Tier 1 subsidiaries on technologies for battery, motor, and electric control system, as well as setting up its own battery factory. Toyota has the most patents in solid state battery technology and will cooperate with Panasonic, which has the second most patents in solid state battery, to develop solid state batteries for vehicles.