KINOKAWA, Japan, Sept 9 (Reuters) - The energy unit of

Japan's Panasonic Holdings ( PCRFF ) has finalised preparations

for the mass-production of its high-capacity electric-vehicle

batteries, the company said on Monday, as it seeks to start

supplying the cell to automakers.

Panasonic Energy's renovated plant in the western prefecture

of Wakayama will serve as the main factory for producing the

4680 cells, which the Tesla supplier says have five

times the capacity of its smaller 2170 cylindrical batteries.

The company has sent samples of the 4680 batteries to some

automakers to which it is already a supplier, and intends to

kick off production after getting the green light from clients,

a Panasonic ( PCRFF ) spokesperson said.

It had previously said it planned to start production of the

4680 cells at the Wakayama plant, where it formerly made parts

for automotive batteries, in the first half of the current

business year that started in April.

The bigger cells, which have a diameter of 46mm and an 80mm

height, will allow automakers to extend the driving range of

electric vehicles and use fewer cells to achieve the same

battery pack capacity, Panasonic Energy said in a statement.

The company held a ceremony to mark the completion of

preparations to start mass-producing the batteries and showed an

inspection line where trays stacked with the silver-coloured

cells could be seen running through.

Panasonic Energy plans to start battery production at an

annual capacity of several gigawatt hours, CEO Kazuo Tadanobu

told reporters after the ceremony, adding the global EV market

was likely to expand over the medium to long-term.

The Wakayama plant is expected to employ roughly 400 staff

in the development and production of the new batteries by March

2025, and serve as a site for trying out processes that it could

implement at other battery factories around the world, the

company said.

Panasonic Energy already makes 2170 and 1860 cylindrical EV

batteries at its Suminoe and Kaizuka plants in Japan.

The battery manufacturer and automaker Subaru, for

which the U.S. is a key market, said last week they will set up

a plant in Gunma prefecture north of Tokyo for the supply of

automotive batteries from the 2028 business year.