尖晶石型 LiMn2O4 转化 CaFe2O4 型 LiMn2O4 的结构和电化学分析,ACS Omega

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尖晶石型 LiMn2O4 转化 CaFe2O4 型 LiMn2O4 的结构和电化学分析
ACS Omega ( IF 3.7 ) Pub Date : 2019-04-08 00:00:00 , DOI: 10.1021/acsomega.9b00588
Kazuhiko Mukai ₁ , Takeshi Uyama ₁ , Ikuya Yamada ₂

Affiliation

锰酸锂作为锂离子电池正极材料备受关注。本研究在6 GPa以上的高压下合成了后尖晶石材料CaFe ₂ O ₄型LiMn ₂ O _{4 (CF-LMO)，并对其晶体结构和电化学性能进行了研究。}CF-LMO 表现出锂离子的一维 (1D) 传导路径，预计该路径优于这些离子的三维传导路径。化学计量的LiMn ₂ O _{4尖晶石(SP-LMO)在600℃时分解为Li}₂ MnO ₃、MnO ₂和Mn ₂ O ₃三相，然后在800℃以上开始转变为CF-LMO结构。。由于Li ₂ MnO ₃相的存在，在1000 °C 下合成的样品的可充电容量（Q _recha ）在1.5 至5.3 V 的电压范围内被限制在∼40 mA h·g ^–1 。样品(=9.1重量％)。此外，富锂尖晶石Li[Li _x Mn _2–_x ]O ₄（x = 0.1、0.2和0.333）也用于CF-LMO的合成。尽管存在大量Li ₂ MnO ₃、MnO ₂和Mn ₂ O _{3相，但由}x = 0.2制备的样品表现出超过120 mA h·g ^–1的Q _recha值和稳定的循环性能。讨论了从 SP-LMO 到 CF-LMO 的结构转变的细节以及 Mn 离子对一维传导路径的影响。

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Structural and Electrochemical Analyses on the Transformation of CaFe2O4-Type LiMn2O4 from Spinel-Type LiMn2O4

Lithium manganese oxides have received much attention as positive electrode materials for lithium-ion batteries. In this study, a post-spinel material, CaFe₂O₄-type LiMn₂O₄ (CF-LMO), was synthesized at high pressures above 6 GPa, and its crystal structure and electrochemical properties were examined. CF-LMO exhibits a one-dimensional (1D) conduction pathway for Li ions, which is predicted to be superior to the three-dimensional conduction pathway for these ions. The stoichiometric LiMn₂O₄ spinel (SP-LMO) was decomposed into three phases of Li₂MnO₃, MnO₂, and Mn₂O₃ at 600 °C and then started to transform into the CF-LMO structure above 800 °C. The rechargeable capacity (Q_recha) of the sample synthesized at 1000 °C was limited to ∼40 mA h·g^–1 in the voltage range between 1.5 and 5.3 V because of the presence of a small amount of Li₂MnO₃ phase in the sample (=9.1 wt %). In addition, the Li-rich spinels, Li[Li_xMn_2–x]O₄ with x = 0.1, 0.2, and 0.333, were also employed for the synthesis of CF-LMO. The sample prepared from x = 0.2 exhibited a Q_recha value exceeding 120 mA h·g^–1 with a stable cycling performance, despite the presence of large amounts of the phases Li₂MnO₃, MnO₂, and Mn₂O₃. Details of the structural transformation from SP-LMO to CF-LMO and the effect of Mn ions on the 1D conduction pathway are discussed.

更新日期：2019-04-08

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