Miralles Carmen, Lana-Villarreal Teresa, Gómez Roberto
Departament de Química Física i Institut Universitari d'Electroquímica, Universitat d'Alacant, Apartat 99, E-03080 Alicante, Spain.
Materials (Basel). 2023 Aug 1;16(15):5402. doi: 10.3390/ma16155402.
Rechargeable magnesium batteries are an attractive alternative to lithium batteries because of their higher safety and lower cost, being spinel-type materials promising candidates for their positive electrode. Herein, MgMnO with a tetragonal structure is synthesized via a simple, low-cost Pechini methodology and tested in aqueous media. Electrochemical measurements combined with in-situ Raman spectroscopy and other ex-situ physicochemical characterization techniques show that, in aqueous media, the charge/discharge process occurs through the co-intercalation of Mg and water molecules. A progressive structure evolution from a well-defined spinel to a birnessite-type arrangement occurs during the first cycles, provoking capacity activation. The concomitant towering morphological change induces poor cycling performance, probably due to partial delamination and loss of electrical contact between the active film and the substrate. Interestingly, both MgMnO capacity retention and cyclability can be increased by doping with nickel. This work provides insights into the positive electrode processes in aqueous media, which is vital for understanding the charge storage mechanism and the correlated performance of spinel-type host materials.
可充电镁电池因其更高的安全性和更低的成本，成为锂电池颇具吸引力的替代品，尖晶石型材料有望成为其正极材料。在此，通过简单、低成本的佩琴尼方法合成了具有四方结构的MgMnO，并在水性介质中进行了测试。电化学测量结合原位拉曼光谱和其他非原位物理化学表征技术表明，在水性介质中，充放电过程通过镁离子和水分子的共嵌入发生。在最初的循环过程中，会发生从明确的尖晶石结构到水钠锰矿型排列的渐进结构演变，从而引发容量激活。伴随而来的巨大形态变化导致循环性能较差，这可能是由于活性膜与基底之间的部分分层和电接触丧失所致。有趣的是，通过镍掺杂可以提高MgMnO的容量保持率和循环性能。这项工作为水性介质中的正极过程提供了见解，这对于理解电荷存储机制以及尖晶石型主体材料的相关性能至关重要。
