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Amorphous FePO 4 /rGO composite is synthesized by a selective chemical precipitation method from the acid-leaching liquor of jarosite residue. When used as a novel anode material for lithium-ion batteries (LIBs), the as-prepared FePO 4 /rGO composite exhibits superior cyclic performance and outstanding high-rate capability in a half cell. More importantly, the full LIBs assembled with FePO 4 /rGO anode and commercial Li(Ni 0.5 Co 0.2 Mn 0.3)O 2 (NCM523) cathode still delivers a high and stable capacity of 674.9/528.7 mA h g−1 after 100/300 cycles at 0.2/0.5 A g−1, indicating the great potential of this FePO 4 /rGO composite as a novel high-performance anode material for LIBs. This work proposes a facile, efficient, and cost-effective strategy for the high-valued utilization of jarosite residue and provides a reference for the design and development of FePO 4 /rGO as a novel anode material for LIBs. [Display omitted] • FePO 4 /rGO composite is prepared by a selective chemical precipitation method. • The leaching liquor of jarosite residue was used as the Fe source for FePO 4. • FePO 4 /rGO composite exhibits an outstanding lithium ions storage performance. • Synergistic effect of FePO 4 and rGO boosts the electrochemical performance. • The FePO 4 /rGO composite anode shows good performance in full LIBs. Rational utilization of jarosite residue is significantly important from the view of environmental protection and resource recycling. Herein, we report a facile preparation of porous amorphous FePO 4 /reduced graphene oxide (rGO) composite by utilizing the iron resource in jarosite residue with a selective chemical precipitation method, and demonstrate its great potential as a high-performance anode material of lithium-ion batteries (LIBs). The FePO 4 /rGO composite exhibits superior cyclic performance (812.7 mA h g−1 over 300 cycles at 500 mA g−1) and high-rate capability (335.2 mA h g−1 even at a high current density of 10 A g−1) in a half cell. More importantly, the full LIB assembled with FePO 4 /rGO anode and commercial Li(Ni 0.5 Co 0.2 Mn 0.3)O 2 (NCM523) cathode still delivers a high and stable capacity of 674.9/528.7 mA h g−1 upon 100/300 cycles at 200/500 mA g−1, indicating the great potential of this FePO 4 /rGO composite as a new anode material with high lithium storage performance. This work proposes a simple, feasible, and cost-effective strategy for the high-valued utilization of jarosite residue and provides a reference for the design and development of FePO 4 -based anode materials for LIBs. [ABSTRACT FROM AUTHOR]

Ultra-high nickel ternary cathode material with high energy density is a very important material to meet the long driving range of new energy vehicles. However, cobalt has high toxicity, high price and supply chain risks, so the material is being developed in the direction of low cobalt or no cobalt. For ultra-high nickel cobalt free cathode material with high theoretical capacity (LiNi0.9Mn0.1O2, NM90), the lattice collapse and particle fragmentation caused by microcracks during long cycle will lead to inferior rate performance and cycle life. At present, the effect of different cobalt content on structure and electrochemical properties of cobalt-free cathode material is rarely reported. Therefore, based on cobalt-free precursors, the effects of proper Co doping on structure and electrochemical properties of NM90 material are studied in depth. It showed that proper Co doping can effectively reduce cationic mixing and improve Li+diffusion rate of NM90 material. The NM90–1.5%Co material exhibits discharge specific capacity of 167.1 mA h g−1after 100 cycles at 1C and 121.2 mA h g−1after 200 cycles at 5C, respectively. Furthermore, NM90–1.5%Co material shows an initial discharge specific capacity of 144.1 mA h g−1at 10C. Therefore, Co doping provides a feasible way to improve the structural stability and electrochemical performances of ultra-high nickel cobalt free cathode material.

The ultra-high nickel cathode material has important application prospect in power lithium-ion batteries. However, the poor structural stability and serious surface/interfacial side reactions during long cycles severely hinder the material's practical application. In this paper, Cs+doping and polymethyl methacrylate (PMMA) coating are used to synergistically modify the NCM955 material. The results show that the corresponding discharge specific capacity of NCMCs-2@P-2 material reaches 152.02 mAh/g at 1 C (1 C = 200 mA/g) and 125.66 mAh/g at 5 C after 300 cycles, and the capacity retention is 78.11% and 72.21%, respectively. In addition, it still maintains 156.36 mAh/g discharge specific capacity at 10 C, and these rate and cycle properties exceed those reported on ultra-high nickel cathode material. Moreover, NCMCs-2@P-2 material has higher migration energy barrier of Ni2+and lower migration energy barrier of Li+than that of NCM955 material. Therefore, NCMCs-2@P-2 material has excellent electrochemical properties, which has been proved by a series of structural characterization, theoretical calculation and performance test. The synergistic enhancement of Cs+doping and PMMA coating accelerates lithium ion diffusion kinetics, stabilizes crystal structure, and inhabits surface/interface side reaction.

LiMn2O4is 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 Li0.94Na0.06Mg0.08Mn1.92O4and 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+.

A facile Nb-doping is applied to a high-Ni, low-Co LiNi0.94Co0.02Al0.04O2cathode material (NCA94). Crystallographic structures, morphologies and electrochemical properties of the pristine and Nb-doped samples are investigated. Nb-doping does not obviously affect the structure and morphology of the material. However, appropriate dose of Nb-doping can suppress the Li+/Ni2+cation mixing and strengthen the structure, thereby improving cycle life, lowering self-discharge and inhibiting cracking during cycles. The cathode with 0.3 wt% Nb-doping (NCA94-3) exhibits significantly improved structural stability and electrochemical performance. It delivers 172.0 mAh g−1after 300 charge-discharge (voltage window: 2.8–4.3 V) cycles at 2 C (1 C = 220 mA g−1) with a capacity retention of 88.7 %, whereas the pristine one shows a capacity of only 129.9 mAh g−1after 300 cycles with a capacity retention of 67.4 % under the same test condition. The self-discharge of the cathode can also be effectively suppressed by Nb-doping. Moreover, after 300 cycles at 2 C, the spherical morphology of NCA94-3 can be maintained well but NCA94-0 cracks obviously.

High-nickel ternary LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode materials modified by Na-doping and MgF2 coating are synthesized by high-temperature solid-phase method. The morphology and structure of the materials are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performances test shows that the initial discharge specific capacity of the pristine NCM811 sample is 173 mAh/g at 0.5C, and the discharge specific capacity after 100 cycles is 131 mAh/g. However, when the doping amount of sodium ion is 0.05, 0.1, 0.15 respectively (NCM811-0.05Na, NCM811-0.1Na, NCM811-0.15Na), the corresponding initial discharge specific capacity of the sample is 187, 191, 179 mAh/g, and the corresponding discharge specific capacity after 100 cycles is 140, 158, 119 mAh/g. Discharged at 0.1, 0.5, 1, 2, 5 and 10C rate, the discharge specific capacity for the pristine NCM811 samples is 193, 170, 156, 138, 106 and 79 mAh/g respectively, while the corresponding value for NCM811-0.1Na samples is 203, 191, 180, 165, 137 and 105 mAh/g respectively. And for the sample modified by Na doping and MgF2 coating (NCM811-Na@MgF2), the corresponding discharge specific capacity is 210, 196, 183, 172, 146 and 126 mAh/g respectively. It can be seen that the synergistic modification by Na doping and MgF2 coating is beneficial to the improvement of electrochemical performances of high nickel ternary NCM811 cathode material.

High-nickel ternary LiNi0.8Co0.1Mn0.1O2(NCM811) cathode materials modified by Na-doping and MgF2coating are synthesized by high-temperature solid-phase method. The morphology and structure of the materials are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performances test shows that the initial discharge specific capacity of the pristine NCM811 sample is 173 mAh/g at 0.5C, and the discharge specific capacity after 100 cycles is 131 mAh/g. However, when the doping amount of sodium ion is 0.05, 0.1, 0.15 respectively (NCM811-0.05Na, NCM811-0.1Na, NCM811-0.15Na), the corresponding initial discharge specific capacity of the sample is 187, 191, 179 mAh/g, and the corresponding discharge specific capacity after 100 cycles is 140, 158, 119 mAh/g. Discharged at 0.1, 0.5, 1, 2, 5 and 10C rate, the discharge specific capacity for the pristine NCM811 samples is 193, 170, 156, 138, 106 and 79 mAh/g respectively, while the corresponding value for NCM811-0.1Na samples is 203, 191, 180, 165, 137 and 105 mAh/g respectively. And for the sample modified by Na doping and MgF2coating (NCM811-Na@MgF2), the corresponding discharge specific capacity is 210, 196, 183, 172, 146 and 126 mAh/g respectively. It can be seen that the synergistic modification by Na doping and MgF2coating is beneficial to the improvement of electrochemical performances of high nickel ternary NCM811 cathode material.