YOKOHAMA, Japan -- Nissan Motor Co., fighting falling sales of its Leaf electric vehicle, plans a midcycle update as early as August that aims to deliver a big increase in the Leaf's driving range, a person familiar with the project said.

The improvements will come from squeezing more energy into the Leaf's lithium ion battery. The new battery will be the same size as the current 24-kilowatt-hour power pack but deliver 30 kwh, the source said.

CEO Carlos Ghosn outlined future EV steps at the company's annual shareholders meeting Tuesday, June 23. Nissan is developing a lighter, thinner, cheaper battery to enable driving ranges comparable with gasoline vehicles in the "near future," he said.

Nissan needs a battery breakthrough to help jump-start sluggish sales and ease range anxiety -- the fear that a drained battery will leave EV drivers stranded.

Nissan launched the Leaf in 2010 and has made zero-emission technology and autonomous driving two pillars of its future product plans.

But Leaf sales in the U.S. tumbled 25 percent to 7,742 vehicles through the first five months of the year. Demand is undermined partly by the expiration of various EV tax credits and by a wave of Leafs about to come off lease at diminished value.

Ghosn sought to reassure shareholders that the company aims to stay at the forefront of EV technology.