Excellent Structural Stability-Driven Cyclability in P2-Type Ti-Based Cathode for Na-Ion Batteries

In the current study, we have synthesized Ti-based P2 type Na0.7Ni0.2Cu0.1Ti0.65O2 (NNCT) through the sol-gel route and characterized it for its structural, electrical, and electrochemical properties. The analysis of X-ray diffraction (XRD) data confirmed the existence of a single P2 phase for the sample calcined at 950 degrees C with suppressed Na-ion vacancy ordering. Impedance studies and chronoamperometric data revealed that NNCT exhibited a poor conductivity of similar to 1.37 x 10-7 S cm-1 at room temperature, with the electronic conductivity contribution to the total electrical conduction being only 0.4%. The sample exhibited specific capacities of 83, 54, and 42 mA h g-1 at discharge rates of 0.1C, 0.5C, and 1C, respectively, with remarkable cyclic stability of 96% capacity retention after 700 cycles at 0.5C which makes NNCT an attractive cathode for Na-ion batteries in stationary storage applications. The ex situ XRD analysis confirmed that NNCT maintains a single P2 phase during cycling between 2.0 and 4.2 V. NNCT also exhibited moisture stability, thus enabling the use of a cost-effective water-based slurry for cathode layer fabrication.

Automated summary

In this study, Ti-based P2 type Na0.7Ni0.2Cu0.1Ti0.65O2 (NNCT) was synthesized via the sol-gel route and characterized for its structural, electrical, and electrochemical properties. The analysis confirmed the presence of a single P2 phase and suppressed Na-ion vacancy ordering. NNCT showed poor conductivity and low electronic conductivity contribution to the total electrical conduction. It exhibited high specific capacities and remarkable cyclic stability, making it an attractive cathode material for Na-ion batteries in stationary storage applications. The ex situ XRD analysis confirmed its phase stability and it also exhibited moisture stability, allowing for the use of a cost-effective water-based slurry for cathode layer fabrication.