Lithium-rich layered oxides Li1.2Ni0.133Mn0.534Co0.133O2 were obtained by the solid-phase reaction of precursors with a lithium source and subsequent high-temperature annealing. The effect of the precursor synthesis method on the functional properties of the resulting cathode material was studied. The precursors were synthesized by the coprecipitation method (hydroxide and carbonate precursors) and the solvothermal method (oxalate and hydroxide precursors). In the coprecipitation method, the precipitant and the pH of precipitation was varied; and in the solvothermal method, the reaction medium–precipitant combination was. The sample produced by the solvothermal method has a high discharge capacity of 233.2 mA h/g (0.1C) and 175.3 mA h/g (0.4C) with a residual discharge capacity of 94

The influence of the precursor synthesis method on the functional properties of cathode material based on lithium-rich oxides was studied. Precursors were obtained by co-precipitation method (hydroxide and carbonate precursors) and solvothermal method (hydroxide and oxalate precursors). Within the selected synthesis methods, the parameters were changed by varying the precipitant and pH of precipitation during the synthesis by co-precipitation method and the reaction medium/precipitant combinations during the solvothermal synthesis method. The solid-phase reaction of the investigated precursors with lithium source and subsequent high-temperature annealing resulted in lithium-rich layered oxides of the composition Li1.2Ni0.133Mn0.534Co0.133O2. The sample synthesized by solvothermal method exhibits high discharge capacity values of 233.2 mAh/g (0.1 C) and 175.3 mAh/g (0.5 C) with residual discharge capacity of 94 and 80.5%, respectively. The samples with comparable electrochemical performance are similar in morphology. These materials are agglomerated and characterized by a bimodal distribution with maxima in the 14–19 μm and 55–60 μm regions. An approach that takes into account the relationship between morphology and electrochemical properties will allow the preparation of higher performance electrode materials for lithium-ion battery.

We have studied the effect of doping with tin and titanium cations on the electrochemical performance of lithium-rich cathode materials. Samples for this investigation were prepared via coprecipitation of precursors, followed by solid-state reaction with a lithium and tin (titanium) source. The cathode materials have been characterized by X-ray diffraction, scanning electron microscopy, and X-ray microanalysis and tested in lithium half-cells in galvanostatic cycling mode at various current densities. The titanium-doped material had a considerably higher specific discharge capacity (270 mAh/g) in comparison with the undoped and tin-doped materials (230 mAh/g). As the charge/discharge current was raised, the titanium-doped sample exhibited the best cycling stability among all of the materials. In addition, both doped materials had a smaller voltage hysteresis in comparison with the undoped sample.

Li-rich Mn-based layered oxides are among the most promising cathode materials for next-generation lithium-ion batteries, yet they suffer from capacity fading and voltage decay during cycling. The electrochemical performance of the material can be improved by doping with Mg. However, the effect of Mg doping at different positions (lithium or transition metals) remains unclear. Li1.2Mn0.54Ni0.13Co0.13O2 (LR) was synthesized by coprecipitation followed by a solid-state reaction. The coprecipitation stage was used to introduce Mg in TM layers (sample LR-Mg), and the solid-state reaction (st) was used to dope Mg in Li layers (LR-Mg(st)). The presence of magnesium at different positions was confirmed by XRD, XPS, and electrochemical studies. The investigations have shown that the introduction of Mg in TM layers is preferable in terms of the electrochemical performance. The sample doped with Mg at the TM positions shows better cyclability and higher discharge capacity than the undoped sample. The poor electrochemical properties of the sample doped with Mg at Li positions are due to the kinetic hindrance of oxidation of the manganese-containing species formed after activation of the Li2MnO3 component of the composite oxide. The oxide LR-Mg(st) demonstrates the lowest lithium-ion diffusion coefficient and the greatest polarization resistance compared to LR and LR-Mg.

This article studies the doping of Li-rich cathode materials. Aluminum and iron were chosen as dopants. Li-rich cathode materials for lithium-ion batteries, which were composed of Li1.2Ni0.133Mn0.534Co0.133O2 with a partial replacement of cobalt (2 at %) by iron and aluminum, were synthesized. The dopants were introduced at the precursor synthesis stage by co-precipitation. The presence of Fe and Al in the composition of the synthesized samples was proved by inductively coupled plasma mass spectrometry, X-ray diffraction analysis and X-ray microanalysis. The cathode materials were tested electrochemically. The incorporation of Al and Fe into the structure of lithium-enriched materials improved the cyclability and reduced the voltage fade of the cathodes. An analysis of the electrochemical data showed that the structural changes that occur in the initial cycles are different for the doped and starting materials and affect their cycling stability. The partial cation substitution suppressed the unfavorable phase transition to lower-voltage structures and improved the electrochemical performance of the materials under study.

A lithium-rich cathode material for lithium-ion batteries, Li1.2Ni0.133Mn0.534Co0.133O2, was synthesized by three methods. Cathode materials based on this compound in which cobalt was partially replaced by cadmium were obtained. The effects of preparation method and cadmium introduction method on the electrochemical characteristics of the materials were investigated. The oxides were obtained by co-precipitation in which cadmium was added either in the precursor preparation stage or in the stage of solid-state reaction of the precursor with the lithium source, or in the solvothermal synthesis. The presence of cadmium in the materials was proved by inductively coupled plasma mass spectrometry, powder X-ray diffraction, and electron probe microanalysis. The most part of cadmium in the modified materials existed as an oxide coating on the surface of the active material particles. The electrochemical testing of the materials in half-cells with a lithium anode showed that the sample with a more uniform coating obtained by adding cadmium during the precursor synthesis had better electrochemical characteristics than the pristine material (95% versus 84% reversibility by the 100th cycle).

Li-rich oxides are promising cathode materials for Li-ion batteries. In this work, a number of different compositions of Li-rich materials and various electrochemical testing modes were investigated. The structure, chemical composition, and morphology of the materials synthesized were studied by XRD with Rietveld refinement, ICP-OES, and SEM. The particle size distributions were determined by a laser analyzer. The galvanostatic intermittent titration technique and galvanostatic cycling with different potential limits at various current densities were used to study the materials. The electrochemical study showed that gradual increase in the upper voltage limit (formation cycles) was needed to improve further cycling of the cathode materials under study. A comparison of the data obtained in different voltage ranges showed that a lower cut-off potential of 2.5 V (2.5–4.7 V range) was required for a good cyclability with a high discharge capacity. An increase in the low cut-off potential to 3.0 V (3.0–4.8 V voltage range) did not improve the electrochemical performance of the oxides and, on the contrary, considerably decreased the discharge capacity and increased the capacity fade. The LMR35 cathode material (Li1.149Ni0.184Mn0.482Co0.184O2) demonstrated the best functional properties among all the compositions studied.

The influence of Ti doping on the functional properties of the lithium-rich Li-1.2(Mn0.67Ni0.17Co0.15Ti0.02)(0.8)O-2 cathode material for lithium-ion batteries was studied. The oxide was synthesized by co-precipitation of the appropriate carbonate precursor followed by a solid-state reaction. Doping 2 at % titanium in the transition metal sites increased the material energy and improved its cycling performance. Evidence in favor of positive doping effect on the kinetics of the processes occurring in the cathode material during cycling was obtained.

A comparative study was made of the effect of the dopant nature on the electrochemical performance of lithium-rich oxides of the general composition 0.5Li2MnO3⋅0.5LiMn0.33Ni0.33Co0.31M0.02O2 (M = Mg, Cr, Zr). The obtained materials were tested as cathodes in CR2032 coin-type cells versus lithium metal. The results of the study attested to the fact that the main role in the degradation of the material is played by the migration of transition metals, which depends on the dopant-oxygen binding energy. The doping with magnesium suppresses the phase transition, thus stabilizing the oxide structure. By the 110th cycle in the voltage range of 2.5–4.8 V at a current of 100 mA/g, the sample doped with magnesium retains 10% more specific energy than the initial oxide.

Lithium-rich oxides with different compositions are synthesized by coprecipitation method and tested as cathode materials for lithium-ion batteries (LIBs).The paper presents research into the degradation processes: capacity and voltage fade during cycling life.The lithium mobility is known to make one of the major contributions to LIBs lifetime.Therefore, galvanostatic intermittent titration (GITT) is provided to estimate lithium-ion diffusion coefficients (DLi+).We also calculate ohmic and polarization resistance values.There is shown the influence of the structural transformation of lithium-rich oxides on their kinetic parameters.We make an assumption about the optimal composition of such cathode materials for good electrochemical properties.

Li-rich oxides of different phase compositions xLi(2)MnO(3)center dot(1-x)LiMO2 are synthesized by coprecipitation of mixed transition metal carbonates followed by solid-state reaction with lithium hydroxide. X-ray powder diffraction, scanning electron microscopy, and magnetic studies are used to characterize the pristine structure of the oxides with different compositions. The materials are tested as positive electrode in lithium half-cells. Galvanostatic charge-discharge measurements are performed at different current densities. The lithium-ion diffusion coefficients (DLi+) are estimated from the cyclic voltammetry experiments and found to reach maximum values for composition at x=0.35 having the best electrochemical characteristics.

Li-excess transition metal oxides of the general composition xLi(2)MnO(3)center dot(1-x)LiMO2(M=MnaNibCoc, a+b+c=1) are synthesized by coprecipitation method. Synthesis conditions for obtaining spherical particles with porous structure were determined. The influence of the oxide phase composition on their electrochemical performance as cathode materials is studied in lithium half-cells. All the samples show very high first-cycle coulombic efficiencies (more than 90%) in the voltage range of 2.5-4.8 V at a current density of 0.5C. It is reported that the Li-rich oxide of the composition 0.35Li(2)MnO(3)center dot 0.65LiMn(1/3)Ni(1/3)Co(1/3)O(2) shows the better cycling performance in terms both discharge capacity and energy density and the best rate capability compared with the samples with larger and smaller contents of Li2MnO3.

Composites based on electrochemically active components, LiFePO 4 , LiMn 2 O 4 and LiNi 0.82 Co 0.18 O 2 , for the use as cathode materials for lithium-ion batteries were synthesized using ultrasonic treatment. The effects of the sonication mode (series LiFePO 4 –LiMn 2 O 4 ) and component ratio (series LiFePO 4 –LiNi 0.82 Co 0.18 O 2 ) on the electrochemical performance of the resulting composites were studied. The obtained composites were examined by scanning electron microscopy and powder X-ray diffraction and tested in coin-type cells with lithium anode. Positive electrodes based on the obtained composites showed enhanced electrochemical performance.

Lithium-rich transition metal complex oxides of the general composition x Li 2 MnO 3 • •(1– x )LiMO 2 (M = Mn a Ni b Co c , a + b + c = 1) were synthesized by coprecipitation and modified Pechini method. The influence of the oxide phase composition on their electrochemical performance as cathode materials was studied in lithium half-cells. Effects of the synthetic approach and synthesis conditions on the morphology and electrochemical characteristics of the materials obtained were considered. The composition 0.35Li 2 MnO 3 • •0.65LiMn 1/3 Ni 1/3 Co 1/3 O 2 demonstrates the highest discharge capacity retention during cycling. The samples with discharge capacity of 290 mA h g –1 were obtained.

Li-rich layered oxides Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 were synthesized by modified Pechini method using various compositions of the reaction mixture. Difference in the electrochemical performance of cathodes on their basis is explained by different morphology and microstructure of the materials. The porous hierarchical structure favors a better electrochemical performance. The presence of defects, including crystal twins, in the samples is considered to be a major reason that leads to their poor cyclability and rate capability.

Li-excess transition metal oxides of the general composition xLi2MnO3•(1-x)LiMO2 (M=MnaNibCoc, a+b+c=1) are synthesized by coprecipitation method. Synthesis conditions for obtaining spherical particles with porous structure were determined. The influence of the oxide phase composition on their electrochemical performance as cathode materials is studied in lithium half-cells. All the samples show very high first-cycle coulombic efficiencies (more than 90%) in the voltage range of 2.5–4.8 V at a current density of 0.5C. It is reported that the Li-rich oxide of the composition 0.35Li2MnO3•0.65LiMn1/3Ni1/3Co1/3O2 shows the better cycling performance in terms both discharge capacity and energy density and the best rate capability compared with the samples with larger and smaller contents of Li2MnO3.

In this work, we consider influence of synthesis procedures, applying coatings, and formation of core-shell structures on the electrochemical performance of Ni-rich and Li-rich oxides. Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials synthesized by different synthesis procedures exhibit different electrochemical behavior, especially those obtained by sol-gel combustion method. The TEM findings reveal the presence of monoclinic and trigonal phases in the Li-rich materials synthesized. TEM/ED/EDX microanalysis shows that the C2/m monoclinic phase appears to have a variable composition Li-2[M]O-3, where [M] = (Mn, Ni, Co). Whence, on the basis of monoclinic phase we can observe a restricted solid solution with 4 h-Wyckoff Mn-cation positions potentially being occupied by the mixture of three 3d-metal cations [M] = (Mn, Ni, Co). The cyclability of Li-rich oxides is improved by thin alumina films deposited by ALD directly on porous electrodes. The better capacity retention of modified electrodes is explained by suppressing reactions with electrolyte accompanied by growth of SEI film on cathode. The core-shell structures with Ni-rich core and gradient shell enriched with Mn were obtained by coprecipitation and applying the shell material onto LiNi0.8Co0.15Al0.05O2 as received. These structures show better cyclability and rate capability in the extended voltage range of 2.5-4.4 V than the core materials.