我们通过球磨法及后续的高温焙烧合成出了短棒状的NaD.44Mn02,并研究了其作为碱性水溶液钠离子电池正极时,电解液NaOH浓度对其电化学性能的影响.结果表明,提高NaOH浓度有利于抑制嵌氢反应的发生并改善电极的循环性能和倍率性能,但同时也会造成析氧反应的提前触发,浓度过高时则又会降低其倍率性能.Nao.44Mn02在8 moI·L-1 NaOH中表现出了最佳的电化学性能,0.5C(1C=121 mA_g-1)的电流密度下,比容量达到79.2mAh·g-1,50C时,仍能释放出35.3 mAh·g-1的比容量,在0.2-1.2 V(vs.NHE)的电压窗口内,500周后容量保持率64.3％.此外,我们也发现缩小电压窗口可以减少副反应、改善循环性能.Na0.44MnO2在浓碱电解液中也表现出了优异的耐过充能力.上述结果不仅表明通过优化电解液体系和测试条件可大大改善Nao.44Mn02的储钠性能,同时也证实了Na0.44MnO2作为一种水溶液钠离子电池正极材料,在大规模储能领域具有良好的应用前景.“,”Aqueous sodium ion batteries(ASIBs)have attracted considerable attention for large-scale energy storage because of their prominent advantages of low cost,high safety,and environment-friendliness.Among the reported cathode materials for ASIBs,Nao.44Mn02 exhibits outstanding structural and hydrochemical stability,and hence is of much interest to research scholars.However,the reversible capacity of Nao.44Mn02 in most of the reported ASIBs was only 40 mAh·g-1 due to the restriction of stable working windows,although the in spite of theoretical capacity is121 mAh·g-1.Recently,we reported a Zn/Nao.44Mn02 dual-ion battery(AZMDIB)based on a Nao.44Mn02 positive electrode,Zn negative electrode,and 6 molL-1 NaOH electrolvte.The alkaline solution lowered the proton insertion potential and expanded the stable working window of the Nao.44Mn02 electrode,thus enhancing the reversible capacity to 80 mAh·g-1.Previous studies have demonstrated that the composition,concentration,and pH of the electrolytes have significant effects on the stable electrochemical window,rate performance,cycling performance,and other electrochemical properties of aqueous batteries.In addition,it has been reported that the co-intercalation of hydrogen ions can be inhibited by increasing the pH of the electrolyte in order to improve the cyclic stability of the electrode.Therefore,exploring the effect of electrolyte concentration and pH on the electrochemical performance of Nao.44Mn02 can provide insight into the design and optimization of high-performance Zn/Nao.44Mn02 aqueous batteries.Hence,in this work,rod-like Nao.44Mn02 was synthesized by ball milling and subsequent high-temperature calcination,and the influence of NaOH concentration on the electrochemical performance of the Nao.44Mn02 electrode was investigated by adopting five different concentrated electrolytes,1,3,6,8,and 10 mol-L-1 NaOH.The results showed that an increase in NaOH concentration is beneficial for preventing the insertion of protons and improving the cycling performance and the rate performance of the electrode;however,it also leads to premature triggering of the oxygen evolution reaction.Moreover,the rate performance would decrease at high NaOH concentration.The Nao.44Mn02 electrode showed optimal electrochemical performance in 8 mol-L-1 NaOH.At a current density of 0.5C(1C = 121 mA-g-1),a reversible specific capacity of 79.2 mAh·g-1 was obtained,and a capacity of 35.3 mAh·g-1 was maintained even at a high current density of 50C.In the potential window of 0.2-1.2 V(vs.NHE),the capacity retention after 500 weeks was 64.3％,which increased to 78.2％when the potential window was reduced to 0.25-1.15 V,because of the fewer side reactions.In addition,Nao.44Mn02 showed an exceptional ability to sustain overcharging up to 30％in a concentrated alkaline electrolyte(based