The authors regret that there was an error in equations (21) and (24) in the original paper published in Journal of Power Sources. The errors were in the equations in the printed article, but not in the actual equations used to generate the data in the figures. The correct equations should be(21)Msep=Vsep×ρsep(24)Mplate=Vunstplate×ρplate The authors would like to apologise for any inconvenience caused.