Shares of A123 Systems (AONE) rose nearly 50% following their debut Thursday in an initial public offering.

The shares, which priced at $13.50, rose as high as $20 in early trading on the Nasdaq Stock Market.

The IPO price was well above the $10-$11.50 range initially set, which indicated strong demand for the shares.

The maker of rechargeable lithium-ion batteries used in hybrid and electric cars raised $380 million through the sale of about 28.2 million shares, some 2 million more than originally planned.

“We believe A123 is a beneficiary of the anticipation of the money that will be going into green technology,” said Kathy Smith, an analyst with Renaissance Capital, a Greenwich, Ct., IPO research firm.

The company refiled its IPO registration last month, shortly after being selected for a $249 million grant under the U.S. Department of Energy’s electric-car battery initiative. The company initially filed its IPO plans a year ago, just as the stock markets began to tank.

A123 has said proceeds would go toward capital spending and acquisitions among other corporate purposes.

Although the company has never turned a profit, the market for its batteries is at an early stage and much of its business is hitched to the struggling auto industry, the IPO has generated buzz because investors are interested in its green energy technology.

Five companies debuted in IPOs on Thursday, but only two were trading higher in midday trading.

“I wouldn’t use A123 to judge the broader market,” said Smith. “IPO investors are still discerning, and that’s a good thing. The window isn’t open for everything.”

Still the number of debuts this week made it the most active since December 2007, when nine IPOs priced. Most bankers expect between 15 and 20 more offerings through the end of December, roughly equal to what has priced so far this year.