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To improve the rechargeability and conductivity of electrolytic manganese dioxide (EMD) electrodes in rechargeable alkaline manganese batteries. In this work, ultrafine Ag3BiO3 powders were prepared by a novel hydrothermal in situ dispersion method and doped into EMD electrodes by physical grinding. The effects of hydrothermal time, hydrothermal temperature and cetyltriethylammnonium bromide (CTAB) in-situ dispersant on the phase composition and micromorphology of the prepared powders were investigated, and the synthesis process of ultrafine Ag3BiO3 was recommended. Then, the effect of Ag3BiO3 doping amounts on the electrochemical performance of EMD electrodes was further investigated, and the modification mechanism was deeply discussed. The results showed that well-dispersed spherical Ag3BiO3 of about 100 nm could be synthesized at a molar ratio of AgNO3:Bi(NO3)3 of 2:1, with 3 wt% CTAB as in situ dispersant, and a hydrothermal time of 12 h and a hydrothermal temperature of 120 °C. The discharge specific capacities of the EMD electrode doped with 10 wt% Ag3BiO3 were reached 519.9 mAh/g and 98.3 mAh/g after initial and 50 cycles, respectively, which were 323.5%, 72.15% and 108.8%, 18.3% higher than those of the pure EMD electrode and the EMD electrode doped with 10 wt% Bi2O3, respectively. The doping of Ag3BiO3 could increase the discharge voltage of the EMD electrode and improve its redox process. Besides, the Bi3+ ions could form complexes with Mn2+ and Mn3+, inhibit the disproportionation reaction, reduce the production of electrochemically inert products Mn3O4, and also stimulate the second electron discharge of the EMD electrode, which played an important role in lattice stabilisation. Furthermore, the reduction of Ag+ to Ag during charging and discharging could increase the conductivity of the EMD electrode and enhance the modification effect of Bi3+. Therefore, the doping of Ag3BiO3 in the EMD electrode could significantly increase the discharge specific capacity and rechargeability. This is an important contribution to the modification mechanism of Ag3BiO3 doped EMD cathode for rechargeable alkaline manganese batteries. [ABSTRACT FROM AUTHOR]

A high conductivity C/amorphous MnO2 (AMO) for aqueous zinc-ion battery cathode prepared by in-situ liquid-phase co-precipitation was investigated. Low-cost industrial grade flake graphite (FG) and carbon nanotubes (CNT) were used to modify the amorphous manganese dioxide. The carbon material types and the compound amounts on the microstructure of C/AMO were systematically investigated. The electrochemical properties of the cathodes as well as the modification mechanism of the FG and CNT were discussed in detail. And the optimum compound amounts of FG and CNT were 20 and 30 wt%, respectively. It was found that the electrode performance of 30 wt% CNT/AMO was better than that of 20 wt% FG/AMO, which achieved a maximum specific capacity of 304.4 mAh g−1 at a current density of 100 mA g−1 and a capacity retention rate of 101.53% after 100 cycles were obtained. In addition, at a current density of 1 A g−1, the maximum discharge specific capacity and the capacity retention rate could still reach 235.8 mAh g−1 and 67.04% after 600 cycles. It was found that the composite of CNT could strengthen the Mn–O bonding of AMO, and increase the number of the Mn–O bonds and the oxygen vacancies, thus improving the material activity and increasing the charging and discharging capacity. Furthermore, the modification of CNT could also significantly increase the electrical conductivity of the composite and change the pseudo-capacitance behavior of its electrode, thus improving its cathode cycling and multiplier performance. [ABSTRACT FROM AUTHOR]

In order to explore the crystallization behavior of Co‐doped amorphous manganese dioxide(Co‐doped AMO) and to investigate the electrochemical properties of its different crystallization products as cathodes for aqueous zinc ion batteries. In this work, the effects of heat treatment temperature on the microstructure and phase composition of Co‐doped AMO and their electrochemical properties of Zn‐MnO2 battery cathode materials are systematically investigated. The results show that Co‐doping increases the crystallization temperature of pure AMO. When the heat treatment temperature is 400 °C, Co‐doped AMO is amorphous. At 500 and 550 °C, part of the Co‐doped AMO crystallizes into tetragonal spinel structured (Co, Mn)(Co, Mn)2O4 material between MnCo2O4 and Mn3O4. At 650 °C, the crystallized product is completely nano‐α‐Mn(Co)O2 crystal. The maximum discharge specific capacities and the retention rate after 100 cycles of the samples at 100 mA g−1 are 325.40 mAh g−1, 86.88%; 217.00 mAh g−1, 13.94%; 186.68 mAh g−1, 41.01%; and 149.03 mAh g−1, 31.27% for the unheated and 400, 550, 650 °C heat‐treated samples, respectively. It is proved that the Co‐doped AMO without heat treatment is superior to the partially or fully crystallized materials in terms of comprehensive performance and cost as cathode materials for AZIB. [ABSTRACT FROM AUTHOR]