New Ni0.5 Ti2 (PO4 )3 @C NASICON-type Electrode Material with High Rate Capability Performance for Lithium-Ion Batteries: Synthesis and Electrochemical Properties.

Ni0.5 Ti2 (PO4 )3 /C NASICON-type phosphate is introduced as a new anode material for lithium-ion batteries (LIBs). Ni0.5 Ti2 (PO4 )3 /C was synthesized through the sol-gel route and delivered some remarkable electrochemical performances. Specifically, the Ni0.5 Ti2 (PO4 )3 /C electrode demonstrates a high rate capability performance and delivers high reversible capacities ranging from 130 mAh g-1 to about 111 mAh g-1 at current rates ranging from 0.1 C to 5 C in the voltage window of 1.85-3 V (vs. Li+ /Li). In the same voltage range, the material reaches an initial capacity of 105 mAh g-1 with a capacity retention of about 82 % after 1000 cycles at the high current rate of 10 C. The electrodes are also tested in the wider voltage range of 0.5-3 V (vs. Li+ /Li) and show good reversibility and rate capability performance. Moreover, the Ni0.5 Ti2 (PO4 )3 /C electrodes enable fast Li+ diffusion (in the order of 10-13  cm2  s-1 ) compared with other NASICON-type materials. As a result, a first discharge capacity of 480 mAh g-1 is reached.