TY - JOUR AU - Yu, Haoxiang AU - Deng, Chenchen AU - Yan, Huihui AU - Xia, Maoting AU - Zhang, Xikun AU - Wang, Zhen‑Bo AU - Shu, Jie PY - 2021/01/04 Y2 - 2024/03/28 TI - Cu3(PO4)2: Novel Anion Convertor for Aqueous Dual-Ion Battery JF - Nano-Micro Letters JA - Nano-Micro Lett VL - 13 IS - SE - Articles DO - 10.1007/s40820-020-00576-1 UR - https://www.nmlett.org/index.php/nml/article/view/805 SP - 41 AB - <p>Electrode materials which can reversibly react with anions are of interest for aqueous dual-ion batteries. Herein, we propose a novel anion electrode, Cu<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>, for constructing an aqueous dual-ion cell. The Cu<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> electrode can operate in a quasi-neutral condition and deliver a reversible capacity of 115.6&nbsp;mAh&nbsp;g<sup>−1</sup> with a well-defined plateau at −0.17&nbsp;V versus Ag/AgCl. Its reaction mechanism shows that Cu<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> decomposes into Cu<sub>2</sub>O and subsequently is converted into Cu during the initial discharge process. In the following charge process, Cu is oxidized into Cu<sub>2</sub>O. It suggests Cu<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> reacts with OH<sup>−</sup> ions instead of PO<sub>4</sub><sup>3−</sup> ions after the initial discharge process and its potential thereby depends upon the OH<sup>−</sup> ions concentration in electrolyte. Additionally, an aqueous dual-ion cell is built by using pretreated Cu<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> and Na<sub>0.44</sub>MnO<sub>2</sub> as anode and cathode, respectively. During cycling, OH<sup>−</sup> ions and Na<sup>+</sup> ions in electrolyte can be stored and released. Such a cell can provide a discharge capacity of 52.6&nbsp;mAh&nbsp;g<sup>−1</sup> with plateaus at 0.70 and 0.45&nbsp;V, exhibiting the potential of application. This work presents an available aqueous dual-ion cell and provides new insights into renewable energy storage and adjustment of the OH<sup>−</sup> ions concentration in aqueous buffer solution.</p><p>Highlights:</p><p>1 A novel anion electrode Cu<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> is proposed at the first time.<br>2 The reaction mechanism of Cu<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> electrode is investigated.<br>3 The dual-ion cell is constructed by using pretreated Cu<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> and Na<sub>0.44</sub>MnO<sub>2</sub>.</p> ER -