This paper describes a high-capacity lithium-ion battery pack that was newly developed for use in global mass production of the Nissan LEAF electric vehicle. The mass-market Nissan LEAF was launched in December 2010, and mass production began on a global scale in 2012. This development is in line with the Nissan Green Program 2010, a medium-term environmental action plan under which the diffusion of zero-emission cars is being promoted.The lithium-ion battery is one of the key technologies of electric vehicles (EVs). The battery pack accounts for a large proportion of the EV body size, weight and cost. Therefore, achieving a smaller, lighter and less expensive battery pack suitable for global mass production on a scale comparable to vehicle mass production will be an important factor in supporting widespread diffusion of EVs.The newly developed battery pack cuts the weight and costs significantly as a result of simplifying the structures of the battery module and battery pack. The battery pack development policy is outlined below. Downsizing and simplification of componentsReducing the number of components through parts integrationIncreasing local and leading competitive country procurement rates through outsourcingThis paper describes the lithium-ion battery pack and module for global mass production and the key breakthrough technologies that made them possible.