Electrochemical In Situ Synthesis: A New Synthesis Route for Redox Active Manganese Oxides for Rechargeable Sodium Ion Battery through Initial Charge Process
Electrochemical In Situ Synthesis: A New Synthesis Route for Redox Active Manganese Oxides for Rechargeable Sodium Ion Battery through Initial Charge Process
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DOI：
10.1149/2.0851702jes
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发表时间：
2017
影响因子：
3.9
通讯作者：
R. Kataoka;M. Kitta;N. Takeichi;T. Kiyobayashi
中科院分区：
文献类型：
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作者：
R. Kataoka;M. Kitta;N. Takeichi;T. Kiyobayashi
以na2o和m3o4为前驱体复合材料，在电化学电池初始充电过程中原位合成了可充电钠离子电池正极活性材料。与合成金属氧化物（如α-NaFeO 2等）不同，本材料无需热处理。当开始使用Na/Mn比为1.0的前驱体复合材料时，电极在随后的放电过程中输出194 mA h g−1。30次循环后，电极保持84%的初始放电容量。x射线衍射（XRD）和透射电子显微镜鉴定了前驱体复合材料的三个相；即结晶的mn3o4和na2o2以及非晶相。非原位XRD分析表明，原位合成后前驱体中的m3o4在初始电荷过程后转变为λ- mno2。此外，当复合材料的Na/Mn比大于1.0时，我们还发现了复合函数。当我们从Na/Mn比大于1.0的复合材料开始时，可以提供额外的Na量来抵消负极的不可逆容量，从而证明了完整电池的可行性。
Positive electrode active materials for the rechargeable sodium ion battery are in-situ synthesized during initial charge process in an electrochemical cell from precursor composites of Na 2 O 2 and Mn 3 O 4. Unlike the synthesis of metal oxides, eg, α-NaFeO 2, etc., the present materials are subjected to no heat-treatment. When beginning with a precursor composite of which the Na/Mn ratio is 1.0, the electrode delivers 194 mA h g− 1 during the subsequent discharge process. The electrode retains 84% of the initial discharge capacity after 30 cycles. X-ray diffractometry (XRD) and transmission electron microscopy identifies three phases in the precursor composite; ie, crystalline Mn 3 O 4 and Na 2 O 2 as well as an amorphous phase. Ex-situ XRD reveals that Mn 3 O 4 in the precursor transforms to λ-MnO 2 after the initial charge process as a result of the in-situ synthesis. Moreover, we also found the composite functions when the Na/Mn ratio of the composite is more than 1.0. An extra amount of Na can be provided to cancel the irreversible capacity of the negative electrode when we start from a composite of which the Na/Mn ratio is greater than 1.0, whereby we demonstrate the feasibility of a full-cell.