Business Green: General Motors last week became the first US auto manufacturer to begin work on its own electric car battery plant as it continues to lay the groundwork for next year’s launch of its Chevy Volt plug-in hybrid. The company announced that it is to invest $43m (£26m) to lease and renovate a new factory in Browntown, Michigan that will be dedicated to manufacturing Lithium-ion batteries for the Volt and future GM plug-in hybrids. Installation of new equipment at the site is already …