Averianov Timofey, Zhang Xinle, Andris Ryan, Olds Daniel, Zachman Michael J, Pomerantseva Ekaterina
Materials Electrochemistry Group, Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States.
National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States.
ACS Appl Nano Mater. 2025 Apr 7;8(15):7582-7595. doi: 10.1021/acsanm.5c00175. eCollection 2025 Apr 18.
Bilayered vanadium oxides (BVOs) are promising cathode materials for beyond-Li-ion batteries due to their tunable chemistries and high theoretical capacities. However, the large size of beyond-Li ions limits electrochemical cycling and rate capability of BVO electrodes. Recent reports of MXene-derived BVOs with nanoscale flower-like morphology have shown improved electrochemical stability at high rates up to 5C in nonaqueous lithium-ion batteries. Here, we report how morphological stabilization can lead to improved rate capability in potassium-ion batteries (PIBs) through the synthesis and electrochemical characterization of MXene-derived K-preintercalated BVOs (MD-KVOs), which were derived from two VCT precursor materials prepared using two different etching protocols. We show that the etching conditions affect the surface chemistry of the MXene, which plays a role in the MXene-to-oxide transformation process. MXene derived from a milder etchant transformed into a nanoflower MD-KVO with two-dimensional (2D) nanosheet petals (KVO-DMAE) while a more aggressive etchant produced a MXene that transformed into a MD-KVO with one-dimensional (1D) nanorod morphology (KVO-CMAE). Electrochemical cycling of the produced MD-KVOs after drying at 200 °C under vacuum (KVO-DMAE-200 and KVO-CMAE-200) in PIBs showed that electrochemical stability of MD-KVO at high rates improved through the morphological stabilization of 2D particles combined with the control of interlayer water and K ion content. Structure refinement of KVO-DMAE-200 further corroborates the behavior observed during K ion cycling, connecting structural and compositional characteristics to the improved rate capability. This work demonstrates how proper synthetic methodology can cause downstream effects in the control of structure, chemical composition, and morphology of nanostructured layered oxide materials, which is necessary for development of future materials for beyond-Li-ion battery technologies.
双层钒氧化物（BVO）因其可调化学性质和高理论容量，是极具潜力的超越锂离子电池的阴极材料。然而，超越锂离子的大尺寸离子限制了BVO电极的电化学循环和倍率性能。最近关于具有纳米级花状形态的MXene衍生BVO的报道表明，在非水锂离子电池中，其在高达5C的高倍率下具有改善的电化学稳定性。在此，我们通过MXene衍生的钾预插层BVO（MD-KVO）的合成和电化学表征，报告了形态稳定如何导致钾离子电池（PIB）倍率性能的改善，MD-KVO由使用两种不同蚀刻方案制备的两种VCT前驱体材料衍生而来。我们表明，蚀刻条件会影响MXene的表面化学性质，这在MXene到氧化物的转变过程中发挥作用。由较温和蚀刻剂衍生的MXene转变为具有二维（2D）纳米片花瓣的纳米花MD-KVO（KVO-DMAE），而更具侵蚀性的蚀刻剂产生的MXene转变为具有一维（1D）纳米棒形态的MD-KVO（KVO-CMAE）。在PIB中于200°C真空干燥后（KVO-DMAE-200和KVO-CMAE-200）对所制备的MD-KVO进行电化学循环表明，通过二维颗粒的形态稳定结合层间水和钾离子含量的控制，MD-KVO在高倍率下的电化学稳定性得到了改善。KVO-DMAE-200的结构细化进一步证实了在钾离子循环过程中观察到的行为，将结构和组成特征与改善的倍率性能联系起来。这项工作展示了适当的合成方法如何在纳米结构层状氧化物材料的结构、化学成分和形态控制中产生下游效应，这对于开发超越锂离子电池技术的未来材料是必要的。
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