Layered oxovanadium phosphate hydrate (VOPO₄·xH₂O) is considered to be a promising cathode material for potassium-ion batteries. However, its correlation between electrochemical properties and structural changes during electrochemical processes still need further exploration. Herein, monohydrate VOPO₄·H₂O is used as an alkali ion (Li⁺, Na⁺, K⁺) host material that gives superior electrochemical performances in potassium-ion batteries. It has a high discharge capacity of 90 mA h g⁻¹ with a high average potential of 3.5 V and a lifespan of over 650 cycles with 61% retention at 1C rate. Three phase transitions during the potassiation/depotassiation process are observed: K_xVOPO₄ (0 < x < 0.12, d = 7.06 Å) → α_I-K_xVOPO₄ (0.12 < x < 0.48, d = 6.73 Å) → α_II-K_xVOPO₄ (0.30 < x < 0.55, d = 6.55 Å). The small structural change (≤6% on the c-axis) and the full reversibility of the structural transformation ensure the stable cycling; the large interlayer distance allows a fast K-ion diffusion (10⁻⁹–10⁻¹¹ cm² s⁻¹). This study provides a comprehensive understanding on electrochemical performances and structural evolutions of VOPO₄·H₂O. Meanwhile, the small volume variation, high operating potential, and excellent cycling stability of VOPO₄·H₂O can attract more attention to develop other layered materials beyond transition metal oxides.

层状氧钒钒水合物（VOPO ₄ ·xH ₂ O）被认为是钾离子电池的有希望的正极材料。然而，其在电化学过程中的电化学性质与结构变化之间的相关性仍需进一步探索。在此，一水合物VOPO ₄ ·H ₂ O用作碱金属离子（Li ⁺，Na ⁺，K ⁺）主体材料，在钾离子电池中具有优异的电化学性能。它具有90 mA h g ^-1的高放电容量具有3.5 V的高平均电势，寿命超过650次循环，在1C速率下保持61％。在potassiation / depotassiation过程三相转换被观察到：K _X VOPO ₄（0 <X <0.12，d = 7.06埃）→α_我-K _X VOPO ₄（0.12 <X <0.48，d = 6.73埃）→α _II -K _x VOPO ₄（0.30 <x <0.55，d = 6.55Å ）。很小的结构变化（c轴上≤6％）和结构转变的完全可逆性确保了稳定的循环；较大的层间距离可实现快速的K离子扩散（10 ^-9 –10 ^-11  cm ²  s^-1）。这项研究提供了电化学性能和VOPO结构演变的全面了解₄ ·H ₂ O.同时，小体积的变化，工作电位高，并且VOPO优良的循环稳定性₄ ·H ₂ O可以吸引更多的关注，以发展其他分层过渡金属氧化物以外的材料。