Multiscale structural NaTi2(PO4)3 anode for sodium‐ion batteries with long cycle, high areal capacity, and wide operation temperature

Abstract

Though plenty of research has been conducted to improve the low intrinsic electronic conductivity of NASICON‐structured NaTi2(PO4)3 (NTP), realizing sodium‐ion batteries with high areal/volumetric capacity still remains a formidable challenge. Herein, a multiscale design from anode material to electrode structure is proposed to obtain a gadolinium‐ion‐doped and carbon‐coated NTP composite electrode (NTP‐Gd‐C), in which gadolinium ion doping, oxygen vacancy, optimized structure, N‐doped carbon coating, and bridging on the three‐dimensional network are simultaneously achieved. In the whole electrode, the excellent hierarchical electronic/ionic conductivity and structural stability are simultaneously improved via the synergistic optimization of NTP‐Gd‐C. As a result, excellent electrochemical performances of NTP‐Gd‐C electrode with a high areal/volumetric capacity of 1.0 mAh cm−2/142.8 mAh cm−3, high rate capability (58.3 mAh g−1 at 200 C), long cycle life (ultralow capacity fading of 0.004% per cycle under 10,000 cycles), and wide‐temperature electrochemical performances (97.0 mAh g−1 at 2 C under −20°C) are achieved. Moreover, the NTP‐Gd‐C//Na3V2(PO4)3/C full cell also delivers an excellent rate capacity of 42.0 mAh g−1 at 200 C and long‐term high‐capacity retention of 66.2% after 4000 cycles at 20 C.