Lower Diffusion-Induced Stress in Nano-Crystallites of P2-Na 2/3 Ni 1/3 Mn 1/2 Ti 1/6 O 2 Novel Cathode for High Energy Na-ion Batteries.

P2-type Na 2/3 Ni 1/3 Mn 1/2 Ti 1/6 O 2 (NMTNO) cathode is a preeminent electrode material for Na-ion batteries owing to its open prismatic framework, air-moisture stability, inexpensiveness, appealing capacity, environmental benignity, and Co-free composition. However, the poor cycling stability, sluggish Na-ion kinetics induced in bulk-sized cathode particles, cracking, and exfoliation in the crystallites remain a setback. To outmaneuver these, a designing strategy of a mechanically robust, hexagonal nano-crystallites of P2-type Na 2/3 Ni 1/3 Mn 1/2 Ti 1/6 O 2 (NMTNO nano ) electrode via quick, energy-efficient, and low-cost microwave-irradiated synthesis is proposed. For the first time, employing a unified experimental and theoretical approach with fracture mechanics analysis, the mechanism behind the enhanced performance, better structural stability, and lower diffusion-induced stress of NMTNO nano compared to micro-sized Na 2/3 Ni 1/3 Mn 1/2 Ti 1/6 O 2 is unveiled and the electrochemical shock map is predicted. The NMTNO nano cathode provides 94.8% capacity retention after 100 cycles at 0.1 C with prolonged performance for 1000 cycles at 0.5 C. The practical viability of this cathode, tested in a full cell against a hard carbon anode delivered 85.48% capacity retention at 0.14 mA cm -2 after 200 cycles. This work bridges the gap in correlating the microstructural and electrochemical properties through experimental, theoretical (DFT), and fracture mechanics analysis, thereby tailoring efficient cathode with lower diffusion-induced stress for high-energy Na-ion batteries.