Complex sentence: Mg-ions have two valence electrons compared to Li-ions having one, allowing for high volumetric capacities nearly double of Li-ion batteries (3833 mA h/cc versus 2046 mA h/cc).
Split into simpler sentences: Mg-ions have two valence electrons compared to Li-ion's single electron. Mg has volumetric capacities nearly double of Li-ion batteries (3833 mA h/cc versus 2046 mA h/cc).