In this article, key electrochemical features of LiFe_0.5Mn_1.5O₄ (LFMO) such as phase stability, voltage behavior, and redox process during delithiation are investigated using density functional theory calculations implementing both PBE + U and SCAN functionals. Our findings indicate that numerous equally likely intermediates can be formed, regardless of the metallic distribution across all lithium compositions, thereby excluding a biphasic mechanism between LFMO and FMO. The shape of the experimental voltage–composition curve is well reproduced by both functionals predicting a voltage step in the half-lithiated LFMO, and the PBE + U functional is more accurate in predicting quantitatively the Mn and Fe plateaus, while SCAN underestimates them. The redox activity of Li_xFe_0.5Mn_1.5O₄ is primarily governed by the Mn^3+/4+ redox couple in the range of 0.5 ≤ x ≤ 1, whereas the Fe^3+/4+/(3.x+) couple operates in the region of 0 ≤ x ≤ 0.5, aligned with the experimental voltage–composition curves. The investigation of the redox process suggests the possibility of an anionic contribution that may be reversible in the case of the SCAN functional. This discovery paves the path for the next generation of high-voltage, environmentally friendly lithium-ion batteries with remarkable stability, enhanced performance, and cost-effective potential.

中文翻译：

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阐明 LiFe0.5Mn1.5O4 作为高电压、低成本材料的电化学性能


在本文中，研究了 LiFe _0.5 Mn _1.5 O ₄ (LFMO) 的关键电化学特性，例如相稳定性、电压行为和脱锂过程中的氧化还原过程使用密度泛函理论计算实现 PBE + U 和 SCAN 泛函。我们的研究结果表明，无论所有锂成分中的金属分布如何，都可以形成许多同样可能的中间体，从而排除了 LFMO 和 FMO 之间的双相机制。两个泛函预测半锂化 LFMO 中的电压阶跃，可以很好地再现实验电压-成分曲线的形状，并且 PBE + U 泛函在定量预测 Mn 和 Fe 平台方面更准确，而 SCAN 低估了它们。 Li _x Fe _0.5 Mn _1.5 O ₄ 的氧化还原活性主要受 Mn ^3+/4+ 氧化还原的影响电对在 0.5 ≤ x ≤ 1 范围内工作，而 Fe ^3+/4+/(3.x+) 电对在 0 ≤ x ≤ 0.5 范围内工作，与实验电压-成分曲线一致。对氧化还原过程的研究表明，在 SCAN 泛函的情况下，阴离子贡献的可能性可能是可逆的。这一发现为下一代高电压、环保的锂离子电池铺平了道路，该电池具有卓越的稳定性、增强的性能和成本效益潜力。