Microwave-assisted Synthesis and Co, Al Co-modification of Ni-rich LiNi_0.8Mn_0.2O₂ Materials for Li-ion Battery Electrode

Abstract

Due to high specific capacity and cost performance, high-nickel cathode materials have received much attention. However, its further application is hindered by poor stability and safety performance during cycling. In this work, Ni-rich LiNi0.8Mn0.2O2 materials were prepared through microwave-assisted co-precipitation followed by high-temperature solid-phase method, which can be further modified by doping different proportions of Co and Al.The as-prepared materials are characterized and tested with different methods. As a result, LiNi0.8Mn0.1Co0.08Al0.02O2 (NMCA-2) exhibits the best electrochemical performance, whose capacity retention rate reaches 91.39% after 100 cycles at 1C in the voltage range between 2.75 and 4.35 V, and still owns a specific discharge capacity of 160.03 mAh•g -1 at 5C. Its excellent cyclic retention rate can be attributed to the restrained irreversibility of H2→H3 phase transition during cycling with Co and Al doping, and the lower reaction polarization which contributed to the decline of charge transfer resistance, resulting in good cycle and rate performance of the material. Furthermore, high thermal stability of NMCA-2 improves the safety of the material.

Profiting the Co-Modifications of Li2SnO3 Coating and Sn4+ Doping in Co-Free Ni-Rich Cathode Particles for Lithium-Ion Batteries

“…The columnar illustration in Figure a lists the first Coulombic efficiencies of different electrode materials; the NM@Sn-2 electrode achieves the highest with a value of 87.97%, which is better than that of the previously reported cathode. , This suggests that a proper amount of Li 2 SnO 3 modification can improve the electrochemical reversibility of the material and inhibit side reactions, thereby increasing its reversible capacity. The cyclic performances of the corresponding electrodes at different conditions are illustrated in Figure b (25 °C) and Figure c (55 °C), with a higher current density (1 C ).…”

“…The Ni 0.8 Mn 0.2 (OH) 2 precursors were prepared by the microwave-assisted co-precipitation method. , In the conventional synthesis route, stoichiometric NiSO 4 ·6H 2 O and MnSO 4 ·H 2 O are weighed at a mole rate of 8:2 and dissolved in distilled water to form a 500 mL 2.0 mol L –1 mixed metal salt solution. 500 mL of an alkaline solution consists of 4 mol L –1 NaOH solution and 4 mol L –1 NH 3 ·H 2 O solution.…”

“…500 mL of an alkaline solution consists of 4 mol L –1 NaOH solution and 4 mol L –1 NH 3 ·H 2 O solution. Then a 150 mL alkaline aqueous solution with an ammonia concentration of 0.9 mol L –1 is added into the microwave reactor as the reaction bottom solution . After the reaction bottom solution of the microwave reactor is heated to 55 °C under an N 2 atmosphere, the metal saline reaction reagent and alkaline solution are fed into the microwave reactor at 1.5 mL min –1 of flow rate at the same time, and the pH value of a solution is in the range of 11.2–11.3 during the whole reaction process.…”

“…Considering the synergistic effect produced by the coupling of multiple methods, we synthesized an Sn 4+ -doping and nano-Li 2 SnO 3 coating co-modified Co-free, Ni-rich LiNi 0.8 Mn 0.2 O 2 cathode in a one step through the adsorption of SnO 2 sol, followed by high-temperature calcination. The corresponding cycle stability and rate capability for the modified positive electrode are superior to those for the reported LiNi 0.8 Mn 0.2 O 2 -related materials. , Moreover, the long-term cycling durability of the corresponding positive electrode in the soft-packed battery was evaluated to prove the feasibility of the obtained NM-82 electrode material in practical use. Also, theoretical calculations proved that the modified LiNi 0.8 Mn 0.2 O 2 (NM@Sn-2) has a lower Li + migration energy barrier and a higher Li + /Ni 2+ disorder formation energy than the pristine material.…”

Effect of Nb5+ Doping and LiNbO3 Coating on the Structure and Surface of a LiNi0.8Mn0.2O2 Cathode Material for Lithium-Ion Batteries

“…Amongst various candidates, LiNi x Mn 1−x O 2 with a layered structure is a type of prospective positive electrode material because of its high discharging capacity, cost-effectiveness, good thermal stability and large Li + density. 4 Many lithium nickel manganate cathode materials, such as LiNi 0.7 Mn 0.3 O 2 , 5,6 LiNi 0.8 Mn 0.2 O 2 7,8 and LiNi 0.9 Mn 0.1 O 2 , 9,10 have been extensively explored. Numerous studies have shown that the energy density of batteries increases with increasing nickel concentration in LiNi x Mn 1−x O 2 .…”