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. Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ (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 Li_1.2Ni_0.133Mn_0.534Co_0.133O₂ 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 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⋅0.5LiMn_0.33Ni_0.33Co_0.31M_0.02O₂ (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.

Layered Li-rich transition metal oxides are considered among the most promising cathode materials for high energy density lithium-ion batteries. It was studied how the method and conditions of...

The influence of Ti doping on the functional properties of the lithium-rich Li_1.2(Mn_0.67Ni_0.17Co_0.15Ti_0.02)_0.8O₂ 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.

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 (Li_1.149Ni_0.184Mn_0.482Co_0.184O₂) demonstrated the best functional properties among all the compositions studied.