Spinel LiMn 2 O 4 is a popular cathode material in lithium-ion batteries due to its high operating voltage and reversible specific capacity. Synthesizing analogous NaMn 2 O 4 in the spinel structure, for sodium-ion batteries, is challenging due to the thermodynamic instability of the compound, mostly arising due to Jahn–Teller distortion of the Mn 3+ centre. However, post-spinel NaMn 2 O 4 (named as such because the compounds were initially achieved by subjecting a spinel phase to high pressure) could be synthesized at a high temperature and pressure (1373 K and 4.5 GPa, respectively) and is found to be stable at standard conditions. Also, these compounds have a lower ion diffusion barrier than their respective spinels. In this work, an attempt has been made to induce chemical pressure within the system by the use of a heavy cation, i.e., Sn 4+ in the framework, to synthesize post-spinel NaMnSnO 4 at ambient pressure conditions. The as-prepared NaMnSnO 4 samples are characterized with scanning electron microscopy, X-ray diffraction, inductively coupled plasma-atomic emission spectroscopy and galvanostatic cycling with potential limitation measurements.

中文翻译：

---

化学压力稳定的后尖晶石-NaMnSnO4 作为钠离子电池的潜在阴极

尖晶石 LiMn 2 O 4 因其高工作电压和可逆比容量而成为锂离子电池中常用的正极材料。合成钠离子电池尖晶石结构中类似的 NaMn 2 O 4 具有挑战性，因为该化合物的热力学不稳定性主要是由于 Mn 3+ 中心的 Jahn-Teller 畸变引起的。然而，后尖晶石 NaMn 2 O 4（之所以如此命名是因为这些化合物最初是通过将尖晶石相置于高压下获得的）可以在高温和高压（分别为 1373 K 和 4.5 GPa）下合成，并且发现在标准条件下保持稳定。此外，这些化合物的离子扩散势垒低于它们各自的尖晶石。在这项工作中，已经尝试通过使用重阳离子在系统内引起化学压力，即，框架中的 Sn 4+ ，在环境压力条件下合成后尖晶石 NaMnSnO 4 。所制备的 NaMnSnO 4 样品通过扫描电子显微镜、X 射线衍射、电感耦合等离子体原子发射光谱和恒电流循环进行表征，并具有电位限制测量。