LiMn₂O₄ Cathode Materials with Excellent Performances by Synergistic Enhancement of Double-Cation (Na⁺, Mg²⁺) Doping and 3DG Coating for Power Lithium-Ion Batteries

Abstract

LiMn2O4 is a very important cathode material in the field of plug-in hybrids. However, it has limited large-scale practical application because of its severe electrode polarization and rapid capacity decay. By means of synergistic enhancement of double-cation (Na+, Mg2+) doping and three-dimensional graphene (3DG) coating, the Li0.94Na0.06Mg0.08Mn1.92O4/3DG composite cathode material was successfully synthesized via hydrothermal synthesis, high-temperature solid-phase sintering, and freeze-drying. Electrochemical test results display that the initial discharge specific capacity of the Li0.94Na0.06Mg0.08Mn1.92O4/3DG material reaches 146 mAh/g (137 mAh/g for LiMn2O4) at 0.5C, and the specific capacity remains at 130 mAh/g after 100 cycles (99 mAh/g for LiMn2O4). At 10C, the initial discharge specific capacity of the Li0.94Na0.06Mg0.08Mn1.92O4/3DG material is 90 mAh/g (69 mAh/g for Li0.94Na0.06Mg0.08Mn1.92O4 and 38 mAh/g for LiMn2O4), which should be resulted from the synergistic enhancement of double-cation (Na+, Mg2+) doping and 3DG coating. Na+, Mg2+ codoping effectively expands the Li+ diffusion path and the diffusion coefficient of Li0.94Na0.06Mg0.08Mn1.92O4/3DG, and inhibits the dissolution of Mn3+. 3DG coating effectively improves the conductivity and reduces electrode polarization during the charge and discharge course. In addition, 3DG coating also plays an important role in inhibiting the dissolution of Mn3+.

Understanding the Effect of Al Doping on the Electrochemical Performance Improvement of the LiMn2O4 Cathode Material

“…(3) symmetries, respectively, 28 with the F 2g (3) mode being assigned to the Li−O vibrational motion in the LiO 4 tetrahedral environment. 29 Importantly, it is reported that Raman bands of Mn−O vibration are sensitive to the change of the Mn valence state.…”

“…1,2 The performance of Li-ion batteries (energy density, capacity fade, rate capability, and cycling life) is critically dependent on the cathode materials, in which spinel LiMn 2 O 4 has extracted wide attention because of the high thermal stability, environmental friendliness, low cost, and natural abundance of manganese. 3 Nevertheless, when the batteries worked at higher C-rates or at elevated temperatures (over 55 °C), significant capacity fading and structural instability of the LiMn 2 O 4 electrode would occur. 4 The fast capacity decay of LiMn 2 O 4 may result from the following: (1) the coordinated Jahn−Teller effect of high-spin Mn 3+ ions, 5 (2) lattice mismatch between Li + -rich and Li + -deficient domains due to the volume change between the charged and discharge states in the electrode, 6 (3) decomposition of the electrolyte due to the high charge/discharge voltage, 7 and (4) loss of crystallinity during cycling.…”

“…Li-ion batteries (LIBs) have been widely applied in many fields, such as portable electronic devices, electric vehicles, and stationary energy storage. , The performance of Li-ion batteries (energy density, capacity fade, rate capability, and cycling life) is critically dependent on the cathode materials, in which spinel LiMn 2 O 4 has extracted wide attention because of the high thermal stability, environmental friendliness, low cost, and natural abundance of manganese . Nevertheless, when the batteries worked at higher C-rates or at elevated temperatures (over 55 °C), significant capacity fading and structural instability of the LiMn 2 O 4 electrode would occur .…”

Multiple Influences of Nickel Concentration Gradient Structure and Yttrium Element Substitution on the Structural and Electrochemical Performances of the NaNi0.25Mn0.25Fe0.5O2 Cathode Material

“…Electrochemical energy storage systems have garnered a great deal of studies because of the urgent need for renewable and clean energy. Although lithium-ion batteries (LIBs), which possess high energy density and long cycle life, have been widely used in the electronic equipment, their shortcomings, such as limited and unevenly distributed lithium resources as well as the high cost of raw materials are still major hurdles to the expansion of their adoption. − Therefore, there have been many attempts to look for other energy storage systems to replace LIBs. Similar to LIBs, rechargeable sodium-ion batteries (SIBs) have become an attractive option for energy storage applications due to their low-cost, nontoxic, abundant, and evenly distributed sodium resources. − Since the specific capacity of cathode materials directly determine the energy storage effectiveness of SIBs, seeking suitable cathode materials with high energy density is becoming the primary task for the development of SIBs.…”

Revealing the Multiple Influences of Zr Substitution on the Structural and Electrochemical Behavior of High Nickel LiNi0.8Co0.1Mn0.1O2 Cathode Material

“…Among the numerous energy storage technologies developed in recent years, the lithium-ion battery with its incomparable advantages of high voltage, long cycle life, and environmental friendliness is considered as a preferred technology for large-scale energy storage such as electric vehicles and smart grids. − The first commercial cathode material for LIBs is LiCoO 2 , which has great advantages in ionic conductivity, electronic conductivity, and cycle stability. However, the comparatively low content and high price of cobalt greatly limit widespread application. , Layered oxide LiMO 2 (M represents transition metals) cathode materials have been extensively studied as promising cathode materials with tremendous advantages through the synergy of Ni-Co-Mn. , Especially, the LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode material exhibits high discharge specific capacity that can reach about 240 mAh g –1 , due to the wider redox range of Ni 3+ / 4+ and the relatively small covalent composition of the Ni–O bond.…”