正交晶系
单斜晶系
材料科学
相(物质)
尖晶石
八面体
结晶学
阴极
相变
锂(药物)
氧气
兴奋剂
电阻率和电导率
化学
分析化学(期刊)
晶体结构
物理化学
冶金
医学
物理
光电子学
有机化学
工程类
量子力学
色谱法
电气工程
内分泌学
作者
Dongkyu Choi,HyukSang Kwon,Seonguk Lim,Taekyun Jeong,Heechul Jung,Yong‐Il Kim,Dongwook Han
出处
期刊:Energy & Fuels
[American Chemical Society]
日期:2023-01-09
卷期号:37 (2): 1404-1413
被引量:2
标识
DOI:10.1021/acs.energyfuels.2c03899
摘要
Mn-rich orthorhombic (o)-LiMn1–xTixO2 with a stable oxygen/cation site occupancy and cycling-dependent phase transition is explored as a novel Co- and Ni-free cathode material for Li-ion rechargeable batteries. Typical o-LiMnO2 suffers from oxygen deficiency, cation mixing between Li and Mn, and monoclinic (m)-Li2MnO3 secondary phase with low conductivity. Together with these drawbacks, the gradual, irreversible phase transition from layered o-LiMnO2 into spinel-like cubic (c)-LixMnO2 (x ≈ 0.5) during repeated charge/discharge cycles degrades the cycling performance of o-LiMnO2 despite the activation of electroactive c-LixMnO2 (x ≈ 0.5). By contrast, o-LiMn1–xTixO2 consists of Ti-doped o-LiMnO2 and c-LiTiO2 as the primary and secondary phases, respectively. The presence of Ti–O bonds, stronger than the existing Mn–O bonds, improves the structural stability of Ti-doped o-LiMnO2 by reducing the imperfections of the oxygen/cation lattices (including Mn octahedral sites associated with the Jahn–Teller distortion) in Ti-doped o-LiMnO2 during the long-term synthesis under an inert atmosphere. In addition, the electrochemically inactive (>2 V vs Li+/Li) c-LiTiO2 phase with high conductivity serves as a pillar that suppresses the severe structural collapse of Ti-doped o-LiMnO2 through an abrupt phase/structural transition during cycling (2–4.5 V). As a result, o-LiMn1–xTixO2 with an optimal Ti content exhibits a higher maximum discharge capacity and superior cycling performance compared to the pristine o-LiMnO2.
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