A positive electrode for an energy storage device includes a first activated carbon material comprising pores having a size of ≦1 nm, which provide a combined pore volume of >0.3 cm3/g, pores having a size of >1 nm to ≦2 nm, which provide a combined pore volume of ≧0.05 cm3/g, and 2 nm. A negative electrode for the energy storage device includes a second activated carbon material comprising pores having a size of ≦1 nm, which provide a combined pore volume of ≦0.3 cm3/g, pores having a size of >1 nm to ≦2 nm, which provide a combined pore volume of ≧0.05 cm3/g, and 2 nm. The total oxygen content in at least the first activated carbon material is at most 1.5 wt. %.