General Motors Co. said Wednesday that a lithium-ion battery undergoing tests at a Warren, Mich., research center exploded, sending an employee to the hospital.

The battery exploded at about 9:00am local time Wednesday at GM's Warren Technical Center, where the auto maker designs and develops new vehicles, a company spokesman said. Emergency personnel examined five employees on the scene and transported one to a local hospital, he said.

The explosion is the latest glitch in the auto industry's efforts to bring electric vehicles to market. GM's battery-powered Volt and Nissan Motor's Leaf had disappointing sales in their first year and several start-up companies producing batteries for electric cars have struggled.

Warren Mayor Jim Fouts said in an interview the explosion inside the lab blew out three of the building's exterior windows and an eight-inch-thick (20cm) door. The building will likely need extensive renovations, he said. "They had extreme testing going on," Fouts said.

GM spokesman Greg Martin said the damage was confined to the lab, which has windows and doors designed to give way in a blast. GM and the city's fire department are investigating.

The GM employee taken to the hospital was listed in stable condition with a suspected concussion and chemical burns, according to another city official.

The battery involved in Wednesday's incident was being developed for all-electric cars, including a coming line of Spark subcompacts, and is made by A123 Systems Inc., people familiar with the matter said. An official from A123 wasn't available for comment.

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A123 last month said it would recall defective battery packs developed for auto makers that were made at its Livonia, Mich., plant. A flaw in the manufacturing process led to defective packs that could cause them to fail, the company then said.

A123, which is owned in part by General Electric Co., is one of several battery companies that built production facilities with aid from the US government. A123 received $249 million in federal grants to build battery facilities.