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.