NEC Corp. said investments in its energy business will reach $1.1 billion over the next eight years, as Japan's biggest maker of personal computers aims to reinvent itself after a decade-long slide in sales.

Spending on factories that make parts for batteries supplied to Nissan Motor Co. and smart-grid equipment will rise to ¥100 billion by the year ending in March 2018, including ¥50 billion this year announced earlier, President Nobuhiro Endo said in an interview Wednesday at the company's Tokyo headquarters.

Endo, a 56 year-old with a doctorate in electrical engineering, last month took over the top job at NEC, whose revenue has fallen by ¥2 trillion from its peak nine years ago as it scaled back money-losing display and overseas PC units. After depending for decades on the capital spending budgets of Japan's phone companies for its sales, the company is now betting its future on energy and cloud computing businesses.