In addition to a weak yen, which can boost overseas earnings, the battery unit is also seeing increased demand for some of its new products, the Nikkei business daily reported.

For the past two years Sony had been planning to offload the unit, which was a pioneer in making lithium-ion batteries for computers and mobile devices but has struggled recently against cheaper South Korean rivals.

A government turnaround fund tried to broker a sale of the battery business to a Nissan Motor Co Ltd and NEC Corp joint venture earlier this year.

However, talks have stalled and Sony has now told the turnaround fund that it will hold on to the battery unit and develop it as a core business, the Nikkei reported, citing unidentified sources.

Sony, which last year sold its chemical business to the government turnaround fund, is trying to revive the fortunes of its consumer electronics business by focusing on cameras, gaming and mobile devices.