High Performance Titanium Antimonide TiSb₂ Alloy for Na-Ion Batteries and Capacitors

Herein, we report for the first time the use of TiSb2 alloy as anode material for sodium-ion batteries (NIBs) and capacitors (NICs). The electrochemical performance of TiSb2 in NIBs shows stable cycling with a capacity of about 225 mAh·g–1 for 200 cycles. Discrepancies with the expected theoretical specific charge are discussed by means of operando XRD and ex situ TEM analysis. The excellent rate capability enables the use of TiSb2 in NICs, achieving promising high energy densities of 132 Wh·kg–1 at 114 W·kg–1 and 65 Wh·kg–1 at 11 kW·kg–1, which are among the best reported values for alloying materials in NICs. However, due to the well-known problem of volume changes upon cycling of alloying materials, the capacity retention needs to be improved. Using cross-linked functional binders as carboxymethyl cellulose–poly(acrylic acid) we enhanced the retention after 1000 cycles from 10% to 63%, paving the way to develop new high-performance anodes for NICs.