New hard carbon electrode material (IMAGE) Tokyo University of Science Caption The higher capacity of this new hard carbon electrode material means that a 19% increase in energy density by weight is possible in sodium-ion batteries compared with lithium-ion batteries Credit Shinichi Komaba from Tokyo University of Science Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.