镍掺杂锰基层状氧化物构建稳定钾离子电池正极材料

Ni-Doped Mn-Based Layered Oxides as Stable Cathode Materials for Potassium-Ion Batteries

摘要: 为应对锂资源短缺对大规模储能的制约，钾离子电池因其资源丰富、成本低廉而备受关注。锰基正极材料虽具有成本与容量优势，但面临Jahn-Teller畸变导致结构不稳定等挑战。本文采用高温固相法制备了系列镍掺杂P2型Na_0.7Mn_1−xNi_xO₂ (x = 0、0.1、0.2、0.3)材料，探究了镍掺杂对正极材料结构和储钾性能的影响。适量Ni掺杂(Mn:Ni = 9:1)使材料(002)晶面间距扩大，有利于K⁺扩散。该材料表现出以赝电容行为为主的高度可逆反应，具有最优的电化学性能，首圈放电容量达94.2 mAh∙g⁻¹，100圈后容量保持率为52.3%，均显著优于其他比例样品。研究表明，适度镍掺杂可有效优化材料性能，为高性能钾离子电池正极材料设计提供了参考。

Abstract: To address the constraints posed by lithium resource scarcity on large-scale energy storage, potassium-ion batteries have attracted considerable attention due to their abundant resources and low cost. Although manganese-based cathode materials offer advantages in cost and capacity, they face challenges such as structural instability induced by Jahn-Teller distortion. In this work, a series of Ni-doped P2-type Na_0.7Mn_1−xNi_xO₂ (x = 0, 0.1, 0.2, 0.3) materials were synthesized via a high-temperature solid-state method to investigate the influence of Ni doping on the structure and potassium storage performance of the cathode. Appropriate Ni doping (Mn:Ni = 9:1) leads to an expansion of the (002) interplanar spacing, which facilitates K⁺ diffusion. The material exhibits a highly reversible reaction dominated by pseudocapacitive behavior and demonstrates optimal electrochemical performance, with an initial discharge capacity of 94.2 mAh∙g⁻¹ and a capacity retention of 52.3% after 100 cycles, both significantly superior to those of other doping ratios. This study indicates that moderate nickel doping can effectively optimize material properties, providing a reference for the design of high-performance cathode materials for potassium-ion batteries.