Comparative investigations of high-rate NaCrO2 cathodes towards wide-temperature-tolerant pouch-type Na-ion batteries from −15 to 55 °C: nanowires vs. bulk

Abstract

To satisfy the practical applications of Na-ion batteries (NIBs), the pursuit of high-rate cathodes, especially with superior wide-temperature-tolerant sodium storage capability is of vital importance. Herein, we first comparatively investigated the sodium-storage performances of NaCrO₂ nanowires (NCO NWs) and conventional bulk NaCrO₂ (BNCO) cathodes within the wide operating temperature range from −15 to 55 °C both in half and pouch-type cells. The investigation comprehensively demonstrated that the one-dimensional (1D) nano-structured NCO NWs exhibited better Na⁺-storage properties in terms of reversible capacity, rate behavior and cycling stability, compared to their counterpart BNCO cathode over the whole testing temperature range. And intrinsic reasons for the enhanced electrochemical performance of the 1D NCO cathode were elucidated in-depth with electrochemical and physicochemical characterization. The NCO NW-based pouch-type devices delivered superior temperature-dependent discharge capacities of ∼79.5 (−15 °C), ∼104.8 (25 °C) and ∼103.6 (55 °C) mA h g⁻¹, along with remarkable capacity retentions of ∼78.3% (−15 °C) after 100 cycles, and ∼92.7% (25 °C)/∼82.8% (55 °C) after 200 cycles at 2C rate. Our contribution here will stimulate large-scale applications of the selected NCO NWs for commercial NIBs to some extent, and provide significant guidance for fine exploration of other NW-based cathodes for wide-temperature-operating NIBs.