High-Performance Zr-Doped P3-Type Na0.67Ni0.33Mn0.67O2 Cathode for Na-Ion Battery Applications

Sodium-ion battery (SIB) technology started to bloom along with lithium-ion batteries (LIBs) as a supportive energy source to alleviate the cost of lithium sources for the development of energy storage devices and electric vehicles. Layered cathode materials are considered potential candidates to produce high-energy-density batteries. Among the layered cathode materials, P3-type cathodes are the least investigated in spite of their capacities, which are comparable to those of P2-type cathodes. P3-type cathodes show high polarization, leading to a poor cycle life, which impedes their extensive use in practical applications. In this work, we report on zirconium doping as an effective strategy to improve cycling stability and reduce voltage fading, another serious issue of layered cathode materials. It is found that an optimum composition of the P3-type cathode with Zr doping at the Mn site, leading to a composition of Na0.67Ni0.33Mn0.64Zr0.033O2, shows good electrochemical performance in terms of retention (89% after 100 cycles) when compared to Na0.67Ni0.33Mn0.60Zr0.067O2 (85% after 100 cycles) and an undoped sample (83% after 100 cycles). Also, remarkable performance is delivered by the Na0.67Ni0.33Mn0.64Zr0.033O2 sample, with a retention rate of 72% after 450 cycles. This result is also supported by an analysis of the amount of polarization for undoped and doped samples, which found that doping helps in improving the diffusion of ions, and the least polarization is obtained for the Na0.67Ni0.33Mn0.64Zr0.033O2 sample.