Bismuth (Bi)-based electrode has aroused tremendous interest in potassium-ion batteries (PIBs) on account of its low cost, high electronic conductivity, low charge voltage and high theoretical capacity. However, the rapid capacity fading and poor lifespan induced by the normalized volume expansion (up to ~ 406%) and serious aggregation of Bi during cycling process hinder its application. Herein, bismuth molybdate (Bi₂MoO₆) microsphere assembled by 2D nanoplate units is successfully prepared by a facile solvothermal method and demonstrated as a promising anode for PIBs. The unique microsphere structure and the self-generated potassium molybdate (K-Mo-O species) during the electrochemical reactions can effectively suppress mechanical fracture of Bi-based anode originated from the volume variation during charge/discharge of the battery. As a result, the Bi₂MoO₆ microsphere without hybridizing with any other conductive carbon matrix shows superior electrochemical performance, which delivers a high reversible capacity of 121.7 mAh·g⁻¹ at 100 mA·g⁻¹ over 600 cycles. In addition, the assembled perylenetetracarboxylic dianhydride (PTCDA)//Bi₂MoO₆ full-cell coupled with PTCDA cathode demonstrates the potential application of Bi₂MoO₆ microsphere. Most importantly, the phase evolution of Bi₂MoO₆ microsphere during potassiation/depotassiation process is successfully deciphered by ex situ X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), and transmission electron microscopy (TEM) technologies, which reveals a combination mechanism of conversion reaction and alloying/dealloying reaction for Bi₂MoO₆ anode. Our findings not only open a new way to enhance the performance of Bi-based anode in PIBs, but also provide useful implications to other alloy-type anodes for secondary alkali-metal ion batteries.

铋（Bi）基电极因其低成本，高电子电导率，低充电电压和高理论容量而引起了钾离子电池（PIB）的巨大兴趣。然而，归一化的体积膨胀（高达〜406％）和Bi在循环过程中的严重聚集会导致快速的容量衰减和使用寿命很短，这阻碍了其应用。此处，钼酸铋（Bi ₂ MoO ₆）由2D纳米板单元组装的微球已通过轻松的溶剂热法成功制备，并被证明是有希望的PIB阳极。独特的微球结构和电化学反应过程中自生的钼酸钾（K-Mo-O物种）可以有效地抑制Bi基阳极的机械断裂，该断裂是由于电池在充电/放电过程中的体积变化引起的。结果，没有与任何其他导电碳基质杂交的Bi ₂ MoO ₆微球显示出优异的电化学性能，其在600个循环中在100mA·g ^-1下提供了121.7mAh·g ^-1的高可逆容量。此外，组装的per四羧酸二酐（PTCDA）// Bi ₂MoO ₆全电池与PTCDA阴极耦合显示了Bi ₂ MoO ₆微球的潜在应用。最重要的是，Bi的相位演化₂的MoO ₆期间potassiation / depotassiation过程微球体已成功由破译易地X射线衍射（XRD），X-射线光电子能谱（XPS），透射电子显微镜（TEM）技术，这些技术揭示了Bi ₂ MoO ₆的转化反应与合金化/脱合金反应的结合机理阳极。我们的发现不仅为增强PIB中Bi基阳极的性能开辟了一条新途径，而且还为用于二次碱金属离子电池的其他合金型阳极提供了有益的启示。