Synthesis And Modification Of Spinel LiMn₂O₄as Cathode Material For Lithium Ion Batteries: Towards Capacity、Rate And Cycling Performance

Due to the unique3d tunnel structure of spinel lithium manganese oxides (LiMn2O4), lithium ion iseasy to intercalate/de-intercalate. As the cathode material for lithium-ion batteries, LiMn2O4has highpower density and high energy density. Also due to its favorable properties such as natural abundance ofmanganese oxide, low cost, good safety, and environmental friendly, it has become very hot in the field ofthe cathode material for lithium-ion batteries. Despite advantages in terms of cost and safety, lithium-ionbatteries with spinel structured LiMn2O4have their limitations. Chief among these is the decrease incapacity that occurs during the repeated charge/discharge cycle and storage, especially at a hightemperature. This certainly constrains its applications in power batteries. In this paper, we take manyresearch, focus on the capacity, rates and cycling performance improvement of spinel lithium manganeseoxides:(1), Synthesis and character of high purity spinel LiMn2O4: Using a sulfuric acid assistedhydrothermal treatment β-MnO2particles were obtained from the electrolytic manganese dioxide (EMD).Via high temperature solid-phase reactions, spinel lithium manganese oxides (LiMn2O4) were producedusing the obtained β-MnO2particles as precursor mixed with LiOH H2O for the lithium ion batterycathodes. Spinel lithium manganese (LiMn2O4) synthesized by the β-MnO2precursor has high crystallinity.The electrochemical tests show that LiMn2O4synthesized by the β-MnO2precursor has greater dischargecapacity, better cycle performance, and better high-rate capability when compared with LiMn2O4synthesized by the EMD precursor.(2), Facile synthesis of LiAl0.1Mn1.9O4as cathode material for lithium ion batteries: The Mn1.9Al0.1O3precursor, prepared from the electrolytic manganese dioxide (EMD) and Al(OH)3, is composed of sphericalparticles with an average diameter of300nm, and has a large interspace. Energy dispersive spectrometer(EDS) indicates the Al element is well distributed in Mn1.9Al0.1O3and LiAl0.1Mn1.9O4. Theelectrochemical tests show the synthesized LiAl0.1Mn1.9O4material has superior rate capability and cyclingperformance at both25°C and55°C, indicating that the Al-doped LiMn2O4could be a promising positiveelectrode material for lithium-ion batteries. In the meantime, the proposed synthesis process is simple, of low-cost, and suitable for a large-scaleproduction.(3), Synthesis and character of porous spherical and polyhedron sphere-like LiAl0.02Mn1.98O4: TheAl-doped spherical MnCO3was synthesie by controlling the crystallization in the process of synthesis tojoin part of Al2(SO4)3instead of MnSO4, the synthesis of the Al-doped spherical MnCO3, as the source ofmanganese at600°C,1100°C for6h，producing the Al-doped spherical Mn2O3and Mn3O4, and whentake them as the precursors, the porous spherical LiAl0.02Mn1.98O4and polyhedron sphere-likeLiAl0.02Mn1.98O4can be produced. Electrochemical tests show that the porous spherical and polyhedronsphere-like structure LiAl0.02Mn1.98O4have good capacity, rates and cycling performance.