Researchers have long sought electrically conductive materials for economical energy-storage devices. Two-dimensional (2D) ceramics called MXenes are contenders. Unlike most 2D ceramics, MXenes have inherently good conductivity because they are molecular sheets made from the carbides and nitrides of transition metals like titanium.   MXenes were co-discovered by Michael Naguib, now a Wigner Fellow at the Department of Energy’s Oak Ridge National Laboratory (ORNL), while pursuing his PhD at Dre...