By Scott Murdoch

SYDNEY Chinese electric vehicle maker Nio Inc said on Wednesday it had raised $1 billion in a two-tranche convertible bond from which it intends to use the proceeds to pay down debt and strengthen its balance sheet.

The company raised $500 million in a six-year put-four convertible bond and the same amount in a seven-year put-five bond.

The bonds will be senior, unsecured notes. The shorter dated bond has a 3.875% interest rate, while the seven year bond's rate is 4.625%, Nio said in a Hong Kong Stock Exchange announcement.

"The company plans to use a portion of the net proceeds from the notes offering to repurchase a portion of the existing debt securities ... and the remainder mainly to further strengthen its balance sheet position as well as for general corporate purposes," the company said.

Nio said in late August it planned to launch its first self-development mobile telephone later this month to improve the appeal of its cars with better software and connectivity.

Nio posted a net loss of 6.12 billion yuan ($839.51 million) in the second quarter, versus a loss of 2.75 billion yuan in the corresponding period a year ago.

(Reporting by Scott Murdoch in Sydney; Editing by Michael Perry)