Cr2P2O7 as a Novel Anode Material for Sodium and Lithium Storage.

The development of new appropriate anode material with low cost is still main issue for sodium-ion batteries (SIBs) and lithium-ion batteries (LIBs). Here, Cr2P2O7 with an in-situ formed carbon layer has been fabricated through a facile solid-state method and its storage performance in SIBs and LIBs has been reported first. The Cr2P2O7@C delivers 238 mA h g-1 and 717 mA h g-1 at 0.05 A g-1 in SIBs and LIBs, respectively. A capacity of 194 mA h g-1 is achieved in SIBs after 300 cycles at 0.1 A g-1 with a high capacity retention of 92.4%. When tested in LIBs, 351 mA h g-1 is maintained after 600 cycles at 0.1 A g-1. The carbon coating layer improves the conductivity and reduces the side reaction during the electrochemical process, and hence improves the rate performance and enhances the cyclic stability.