Chromium tetraphosphide (CrP) as a high-performance anode for Li ion and Na ion batteries

Chromium tetraphosphide (CrP 4 ) nanopowder was synthesized via high-energy mechanical milling (HEMM) and introduced as an anode for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). The as-synthesized monoclinic CrP 4 nanopowder was slightly agglomerated nanoparticles of 100-200 nm consisting of 10-20 nm-sized nanocrystallite aggregates. The CrP 4 electrode underwent conversion reactions with both Li and Na ions by forming Li 3 P and Cr for LIBs and Na 3 P and Cr for SIBs and exhibited high initial discharge and charge capacities (1776 and 1540 mA h g −1 for LIBs and 1125 and 881 mA h g −1 for SIBs, respectively), implying its potential as a high energy density anode for both LIBs and SIBs. In addition, the CrP 4 /carbon (C) nanocomposite was fabricated by mixing the as-synthesized CrP 4 nanoparticles and acetylene carbon black to improve the long term cyclability and high rate capability of CrP 4 . The CrP 4 /C nanocomposite electrode delivered a specific capacity of 860 mA h g −1 after 100 cycles at a current density of 1000 mA g −1 in LIBs and 369 mA h g −1 after 100 cycles at 500 mA g −1 in SIBs. In particular, the CrP 4 /C electrode showed outstanding high rate capability compared to other transition metal-based phosphide anodes for LIBs. Furthermore, the CrP 4 /C electrode showed stable cycling performance even in full cell configuration. The CrP 4 nanoparticles and CrP 4 /C nanocomposite were synthesized via high-energy mechanical milling and applied as anodes for LIBs and SIBs.