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Synergistic Improvement in Capacitive Deionization Performance Using a Novel Phase-Integrated Na0.55Mn2O4@Na0.7MnO2

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journal contribution
posted on 02.02.2021, 03:04 by Yubo Zhao, Yang Liu, Izhar Ullah Khan, Ao Gong, Silu Huo, Kexun Li
Capacitive deionization (CDI) is currently restricted by inferior desalination performance. To overcome this limitation, exploring novel pseudocapacitive materials is ongoing. Herein, we made the first attempt to construct a phase-integrated sodium manganese oxide (NMO) by the intergrowth of Na0.55Mn2O4 with Na0.7MnO2 via a feasible method of one-step high-temperature calcination at various temperatures. The optimal NMO sample sintered at 800 °C (NMO-800), with a formula of 0.71Na0.55Mn2O4@0.29Na0.7MnO2, delivered an ultrahigh desalination capacity of 173.5 mg/g in 500 mM NaCl solution with a voltage of 1.0 V along with remarkable cycling stability, energy consumption, and charge efficiency. Electrochemical and material measurements manifested that the dominant ion removal principle of the phase-integrated NMO samples was the Faradic intercalation/deintercalation reactions and that the core mechanism responsible for the superior desalination capacity of the NMO-800 was associated with its higher levels of intercalation/deintercalation reactions owing to the boosted synergistic effect of biphases as compared with the NMO samples sintered at other temperatures. The presented phase-integration engineering strategy could provide a new perspective on the optimal design of pseudocapacitive materials for high-performance desalination.