Unraveling the effects of inter-site Hubbard interactions in spinel Li-ion cathode materials

Accurate first-principles predictions of the structural, electronic, magnetic, and electrochemical properties of cathode materials can be key in the design of novel efficient Li-ion batteries. Spinel-type cathode materials Li_xMn₂O₄ and Li_xMn_1.5Ni_0.5O₄ are promising candidates for Li-ion battery technologies, but they present serious challenges when it comes to their first-principles modeling. Here, we use density-functional theory with extended Hubbard functionals - DFT+U+V with on-site U and inter-site V Hubbard interactions - to study the properties of these transition-metal oxides. The Hubbard parameters are computed from first-principles using density-functional perturbation theory. We show that while U is crucial to obtain the right trends in properties of these materials, V is essential for a quantitative description of the structural and electronic properties, as well as the Li-intercalation voltages. This work paves the way for reliable first-principles studies of other families of cathode materials without relying on empirical fitting or calibration procedures.

精准预测正极材料的结构、电子、磁性和电化学性质对于新型高效锂离子电池的设计至关重要。尖晶石型正极材料Li_xMn₂O₄和Li_xMn_1.5Ni_0.5O₄在锂离子电池技术中展现出巨大的潜力，然而，它们在第一性原理建模方面却面临着严峻的挑战。本研究采用密度泛函理论结合扩展的Hubbard泛函——即DFT+U+V（包含局域U和局域间V的Hubbard相互作用）——来研究这些过渡金属氧化物的性质。Hubbard参数通过密度泛函微扰理论从第一性原理进行计算。研究表明，尽管U对于获得这些材料性质的准确趋势至关重要，但V对于结构、电子性质以及锂嵌入电压的定量描述同样不可或缺。本研究为不依赖经验拟合或校准程序，对其他系列正极材料进行可靠的第一性原理研究奠定了基础。