Among the potential cathode materials for the upcoming Na-ion battery system, O3-type Na-TM-oxides are promising due to their inherently high initial Na-content; but suffer from instabilities caused due to multiple phase transformations during Na-removal/insertion and sensitivity to air/moisture. Against this backdrop, we have tuned the composition and structural features to suppress the phase transitions and also improve the air/water-stability; so much so that long-term cyclic stability has been achieved with health/environment friendly aqueous processed electrodes. At the anode front, development of carefully tuned bi-phase Na-titanate based electrodes have been able to address the cyclic instability of single-phase Na-titanate (viz., otherwise a ‘safe’ anode), leading to long-term cyclic stability even at high current densities (up to 50C!). These are important steps towards the development of health/environment friendly, cost-effective, safe and high-performance Na-ion batteries.
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