A P2-Na_0.67Co_0.5Mn_0.5O₂ cathode material with excellent rate capability and cycling stability for sodium ion batteries

Abstract

Sodium ion batteries are considered as next-generation energy storage devices; however, stable cathode materials are highly desired and challenging for sodium ion batteries. Herein, we report the preparation of a layered cathode material, P2-Na0.67Co0.5Mn0.5O2, with hierarchical architectures, through a facile and simple sol-gel route. X-ray diffraction (XRD) and high resolution transmission electron microscope elucidated a well-defined P2-type phase structure, and in-situ XRD measurements provided further evidence about the structural stability during desodiation/sodiation. Benefiting from the structural stability, the cathode material delivered a high discharge capacity of 147 mAh g -1 at 0.1 C rate, and excellent cyclic stability with nearly 100% capacity retention over at least 100 cycles at 1 C. More importantly, 88 mAh g -1 was maintained when the electrode was cycled at a very high rate of 30 C, and almost half of its capacity retained over 2000 cycles, which outperform all the reported P2-type cathode materials. With outstanding electrochemical performance and structural flexibility, the P2-Na0.67Co0.5Mn0.5O2 cathode material will promote the practical applications of sodium ion batteries.

Fabricating high-performance sodium ion capacitors with P2-Na0.67Co0.5Mn0.5O2 and MOF-derived carbon

“…The preparation of P2-NCM was described in detail previously [39] . ZIF-8 was prepared from Zn(NO 3 ) 2 ·6H 2 O and 2methylimidazole with the molar ratio of 1:8.…”

Direct evidence for high Na+mobility and high voltage structural processes in P2-Nax[LiyNizMn1−y−z]O2(x, y, z ≤ 1) cathodes from solid-state NMR and DFT calculations

“…In particular, a number of studies have focused on sodium transition metal oxides (Na x TMO 2 , TM ¼ transition metal) as cathode materials due to their high volumetric capacities, yielding volumetric energy densities comparable to current commercial LIBs. [1][2][3][4][5][6][7][8] Layered oxides based on the P2 structure, in Delmas et al's nomenclature system 9 (where 'P' indicates prismatic Na, and '2', AB BA oxygen layer stacking), are promising NIB cathodes with a high Na-ion conductivity. TMO 2 layer glides can occur upon electrochemical Na extraction, leading to phase transitions at high voltage.…”

An effective method to screen sodium-based layered materials for sodium ion batteries

“…Some typical insertion-type electrode materials, such as Na 0.44 MnO 2 , Na x CoO 2 , 9 Na 0.66 Co 0.5 Mn 0.5 O 2 , 10 Li 4 Ti 5 O 12 , 11 and Na 2 Ti 3 O 7 , 12 were widely investigated owing to their superior cyclic stability to the alloy-type and conversion-type ones. 13 Among them, Na-containing layered materials have attracted extensive attention since the layered structure ensures the reversible intercalation/de-intercalation of Na + without serious lattice changes, leading to good cyclic stability and excellent ionic conductivity.…”