Abstract
Cost-efficient and high-performance cathodes play a crucial role in the advancement of grid-scale sodium-ion batteries(SIBs).As promising high-capacity cathode materials for SIBs,O3-type Na-based layered transition metal oxides constantly experience inadequate air stability and complex phase transitions.Herein,a comprehensive investigation was conducted to explore the impact of Ca substitution on both the electrochemical performance and structural stability of O3-Na1-2x CaxNi0.25Fe0.5Mn0.25O2(x=0,0.02 and 0.05)that is pro-posed.With proper Ca content,O3-type Na0.96Ca0.02-Ni0.25Fe0.5Mn0.25O2 can deliver a reversible capacity of 122.1 mAh·g-1 at 10 mA·g-1,with capacity retention of 83.4％after 200 cycles at 50 mA·g-1 and good rate capability.Its air sensitivity is investigated,and its poten-tial as the Na host in full cells has been studied.In situ X-ray diffraction reveals the facilitated O3-P3-O3 phase transitions of such cathode during the whole electrochem-ical reaction.Such a simple and effective strategy may reveal a new avenue for high-stable O3-type cathodes and promote the practical applications of SIBs.
维普
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