Characterization of yttrium substituted LiNi0.33Mn0.33Co0.33O2 cathode material for lithium secondary cells

LiNi_0.33−xMn_0.33Co_0.33Y_xO₂ materials are synthesized by Y³⁺ substitute of Ni²⁺ to improve the cycling performance and rate capability. The influence of the Y³⁺ doping on the structure and electrochemical properties are investigated by means of X-ray diffraction (XRD), scanning electron microscope (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and galvanostatic charge/discharge tests. LiNi_0.33Mn_0.33Co_0.33O₂ exhibits the capacity retentions of 89.9 and 87.8% at 2.0 and 4.0 C after 40 cycles, respectively. After doping, the capacity retentions of LiNi_0.305Mn_0.33Co_0.33Y_0.025O₂ are increased to 97.2 and 95.9% at 2.0 and 4.0 C, respectively. The discharge capacity of LiNi_0.305Mn_0.33Co_0.33Y_0.025O₂ at 5.0 C remains 75.7% of the discharge capacity at 0.2 C, while that of LiNi_0.33Mn_0.33Co_0.33O₂ is only 47.5%. EIS measurement indicates that LiNi_0.305Mn_0.33Co_0.33Y_0.025O₂ electrode has the lower impedance value during cycling. It is considered that the higher capacity retention and superior rate capability of Y-doped samples can be ascribed to the reduced surface film resistance and charge transfer resistance of the electrode during cycling.     

Preparation of pod-like 3D Ni0.33Co0.67Fe2O4@rGO composites and their microwave absorbing properties

The ferrite/reduced graphene oxide (rGO) composites have attracted increasing attention due to the combination of the dielectric loss of rGO and the magnetic loss of ferrites. In this paper, pod-like 3D Ni_0.33Co_0.67Fe₂O₄@rGO composites were prepared using a solvothermal reaction followed by cold quenching. The structures and morphologies of as obtained composites were characterized using X-ray diffractometer, Raman microscope, photoelectron spectroscopy, scanning electron microscope and transmission electron microscope. The Ni_0.33Co_0.67Fe₂O₄ microspheres with a diameter of 100–150?nm were wrapped in rGO rolls due to the shrinkage of rGO in liquid nitrogen. The rGO sheets with ferrite microspheres wrapped in form the pod-like 3D network morphology. The minimum reflection loss of as-prepared composites reaches ?47.5?dB and the absorption bandwidth (RL<?10?dB) is 5.02?GHz. The composites show much better absorbing performances than pure Ni_0.33Co_0.67Fe₂O₄ microspheres and Ni_0.33Co_0.67Fe₂O₄-rGO mixture formed by mechanically blending of cold quenched pure rGO and ferrite microspheres.     

One-step hydrothermal synthesis and enhanced microwave absorption properties of Ni0.5Co0.5Fe2O4/graphene composites in low frequency band

Ni_0.5Co_0.5Fe₂O₄/graphene composites were synthesized successfully via one-step hydrothermal method. The crystal structure, morphology and corresponding elemental distribution, electromagnetic parameters and microwave absorption performances of the as-prepared composites were measured by XRD, SEM, TEM and VNA, respectively. The results indicated that the microwave absorbing performance can be obviously enhanced through the addition of graphene in a suitable range, the magnetic loss plays a dominant contribution for the microwave absorption of composites. The maximum reflection loss of ?30.92?dB at 0.84?GHz with a ?10?dB bandwidth over the frequency range of 0.58–1.19?GHz is obtained when the composite contains 12?wt% graphene and the thickness of sample is 4?mm. This investigation presents a simple method to prepare Ni_0.5Co_0.5Fe₂O₄/graphene composites with excellent microwave absorption performance in the low frequency band of 0.1–3?GHz.     

Synthesis and improved electrochemical performance of Al (OH)3-coated Li[Ni1/3Mn1/3Co1/3]O2 cathode materials at elevated temperature

Spherical Li[Ni_1/3Co_1/3Mn_1/3]O₂ powders were synthesized from LiOH·H₂O and coprecipitated spherical metal hydroxide, (Ni_1/3Mn_1/3Co_1/3)(OH)₂ and coated with Al(OH)₃. The Al(OH)₃-coated Li[Ni_1/3Co_1/3Mn_1/3]O₂ showed a capacity retention of 80% at 320 mA g⁻¹ (2 C-rate) based on 20 mA g⁻¹ (0.1 C-rate), while the pristine Li[Ni_1/3Co_1/3Mn_1/3]O₂ delivered only 45% at the same current density. Also, unlike pristine Li[Ni_1/3Co_1/3Mn_1/3]O₂, the Al(OH)₃-coated Li[Ni_1/3Co_1/3Mn_1/3]O₂ cathode exhibits excellent rate capability and good thermal stability.     

The first cycle characteristics of Li[Ni1/3Co1/3Mn1/3]O2 charged up to 4.7 V

In this research, we studied the first cycle characteristics of Li[Ni_1/3Co_1/3Mn_1/3]O₂ charged up to 4.7 V. Properties, such as valence state of the transition metals and crystallographic features, were analyzed by X-ray absorption spectroscopy and X-ray and neutron diffractions. Especially, two plateaus observed around 3.75 and 4.54 V were investigated by ex situ X-ray absorption spectroscopy. XANES studies showed that the oxidation states of transition metals in Li[Ni_1/3Co_1/3Mn_1/3]O₂ are mostly Ni²⁺, Co³⁺ and Mn⁴⁺. Based on neutron diffraction Rietveld analysis, there is about 6% of all nickel divalent (Ni²⁺) ions mixed with lithium ions (cation mixing). Meanwhile, it was found that the oxidation reaction of Ni²⁺/Ni⁴⁺ is related to the lower plateau around 3.75 V, but that of Co³⁺/Co⁴⁺ seems to occur entire range of x in Li_1−x[Ni_1/3Co_1/3Mn_1/3]O₂. Small volume change during cycling was attributed to the opposite variation of lattice parameter “c” and “a” with charging-discharging.     

Synthetic optimization of Li[Ni1/3Co1/3Mn1/3]O2 via co-precipitation

Li[Ni_1/3Co_1/3Mn_1/3]O₂ powders were synthesized from co-precipitated spherical metal hydroxide, (Ni_1/3Co_1/3Mn_1/3)(OH)₂. The preparation of metal hydroxide was significantly dependent on synthetic conditions, such as pH, amount of chelating agent, stirring speed, etc. The optimized condition resulted in (Ni_1/3Co_1/3Mn_1/3)(OH)₂, of which the particle size distribution was uniform and the particle shape was spherical, as observed by scanning electron microscopy. Calcination of the uniform metal hydroxide with LiOH at higher temperature led to a well-ordered layer-structured Li[Ni_1/3Co_1/3Mn_1/3]O₂, as confirmed by Rietveld refinement of X-ray diffraction pattern. Due to the homogeneity of the metal hydroxide, (Ni_1/3Co_1/3Mn_1/3)(OH)₂, the final product, Li[Ni_1/3Co_1/3Mn_1/3]O₂, was also significantly uniform, i.e., the average particle size was of about 10 μm in diameter and the distribution was relatively narrow. As a result, the corresponding tap-density was also high approximately 2.39 g cm−3, of which the value is comparable to that of commercialized LiCoO₂. In the voltage range of 2.8-4.3, 2.8-4.4, and 2.8-4.5 V, the discharge capacities of Li[Ni_1/3Co_1/3Mn_1/3]O₂ electrode were 159, 168, and 177 mAh g⁻¹, respectively. For elevated temperature operation (55 °C), the resulted capacity was of about 168 mAh g⁻¹ with an excellent cyclability.     

Ultrathin CeO2 coating for improved cycling and rate performance of Ni-rich layered LiNi0.7Co0.2Mn0.1O2 cathode materials

In this study, we have successfully coated the CeO₂ nanoparticles (CeONPs) layer onto the surface of the Ni-rich layered LiNi_0.7Co_0.2Mn_0.1O₂ cathode materials by a wet chemical method, which can effectively improve the structural stability of electrode. The X-ray powder diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) are used to determine the structure, morphology, elemental composition and electronic state of pristine and surface modified LiNi_0.7Co_0.2Mn_0.1O₂. The electrochemical testing indicates that the 0.3?mol% CeO₂-coated LiNi_0.7Co_0.2Mn_0.1O₂ demonstrates excellent cycling capability and rate performance, the discharge specific capacity is 161.7?mA?h?g^?1 with the capacity retention of 86.42% after 100 cycles at a current rate of 0.5?C, compared to 135.7?mA?h?g^?1 and 70.64% for bare LiNi_0.7Co_0.2Mn_0.1O₂, respectively. Even at 5?C, the discharge specific capacity is still up to 137.1?mA?h?g^?1 with the capacity retention of 69.0%, while the NCM only delivers 95.5?mA?h?g^?1 with the capacity retention of 46.6%. The outstanding electrochemical performance is assigned to the excellent oxidation capacity of CeO₂ which can oxidize Ni²⁺ to Ni³⁺ and Mn³⁺ to Mn⁴⁺ with the result that suppress the occurrence of Li⁺/Ni²⁺ mixing and phase transmission. Furthermore, CeO₂ coating layer can protect the structure to avoid the occurrence of side reaction. The CeO₂-coated composite with enhanced structural stability, cycling capability and rate performance is a promising cathode material candidate for lithium-ion battery.     

Characterization of high tap density Li[Ni1/3Co1/3Mn1/3]O2 cathode material synthesized via hydroxide co-precipitation

Li[Ni_1/3Co_1/3Mn_1/3]O₂ cathode material for lithium ion batteries was prepared by mixing metal hydroxide, (Ni_1/3Co_1/3Mn_1/3)(OH)₂, with 6% excess LiOH followed by calcinations. The (Ni_1/3Co_1/3Mn_1/3)(OH)₂ with secondary particle of about 12 μm was prepared by hydroxide co-precipitation. The tap density of the obtained Li[Ni_1/3Co_1/3Mn_1/3]O₂ powder was 2.56 ± 0.21 g cm⁻³. The powder was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), particle size distribution (PSD) and galvanostatic charge-discharge cycling. The XRD pattern of Li[Ni_1/3Co_1/3Mn_1/3]O₂ revealed a well ordered hexagonal layered structure with low cation mixing. Secondary particles with size of 13-14 μm and primary particles with size of about 1 μm can be identified from the SEM observations. In the voltage range of 2.8-4.3 V, the initial discharge capacity of the Li[Ni_1/3Co_1/3Mn_1/3]O₂ electrode was 166.6 mAh g⁻¹, and 96.5% of the initial capacity was retained after 50 charge-discharge cycling.     

Novel high-capacity hybrid layered oxides NaxLi1.5-xNi0.167Co0.167Mn0.67O2 as promising cathode materials for rechargeable sodium ion batteries

Relatively low capacity is a technological bottleneck of the development of sodium ion batteries. Herein, we present a series of hybrid layered cathode materials Na_xLi_1.5-xNi_0.167Co_0.167Mn_0.67O₂ (x?=?0.5, 0.6, 0.7, 0.8, 0.9, 1) with composite crystalline structures, which are prepared by co-precipitation method. The combined analysis of XRD, SEM and TEM reveals that the materials are composed of P2 structure, α-NaFeO₂ structure and small amount of Li₂MnO₃. Among the as-prepared materials, Na_0.6Li_0.9Ni_0.167Co_0.167Mn_0.67O₂ delivers an initial reversible capacity of 222?mA?h?g^?1 at 20?mA?g^?1. Even at 100?mA?g^?1, it shows a remarkable discharge capacity of 125?mA?h?g^?1 in the first cycle and remains 60?mA?h?g^?1 after 300 cycles. Such high capacity is achieved by the specific composite structure and sodium ions are proved to be able to intercalate/deintercalate in Li_1.5Ni_0.167Co_0.167Mn_0.67O₂ with α-NaFeO₂ structure. The Ex-situ XRD results of Na_0.6Li_0.9Ni_0.167Co_0.167Mn_0.67O₂ in the first cycle show that the P2 structure is well maintained along with irreversible phase transition of α-NaFeO₂ structure, which is responsible for the long-term capacity fading. Owing to the high discharge capacity, the novel hybrid layered oxides Na_xLi_1.5-xNi_0.167Co_0.167Mn_0.67O₂ with composite structures can be considered as promising cathode materials to promote progress toward sodium-ion batteries.     

Fabrication and characterization of monodispersed Mn0.8Ni0.2Co2O4 mesoporous microspheres for supercapacitor application

The monodispersed Ni doped MnCo₂O₄ mesoporous microspheres were synthesized through a simple ammonium bicarbonate-assisted solvothermal route. The spinel-type crystal structure with a lattice parameter of 8.199?Å for Mn_0.8Ni_0.2Co₂O₄ composition was obtained by using X-ray diffraction analysis. The Brunauer?Emmett?Teller (BET) specific surface area of the sample was found to be 75.78?m² g^?1 with an average pore diameter of 9.88?nm. Electron microscopy studies revealed that the stable mesoporous microspheres are constituted by well-connected aggregates of nanoparticles. The influence of Ni doping on the pseudo-capacitance of MnCo₂O₄ electrode was investigated by means of cyclic voltammetry in 6?M KOH electrolyte. We found that the spinel-type Mn_0.8Ni_0.2Co₂O₄ mesoporous microspheres exhibit specific capacitances of 1822 F g^?1 at a scan rate of 5?mV/s. Furthermore, the electrochemical impedance spectroscopy analysis revealed the low resistance and good electrochemical stability of the sample.     

Electrochemical performance of Li[Co0.1Ni0.15Li0.2Mn0.55]O2 modified by carbons as cathode materials

To enhance specific capacity, cycle performance and rate-capability of lithium-ion battery cathode materials, the Li[Co_0.1Ni_0.15Li_0.2Mn_0.55]O₂ (LCMNO) is modified by coating them with amorphous carbons and by preparing nanocomposites with nanostructured carbons (carbon nanotube and graphene). The carbon-treated LCMNO powders and their cathodes are characterized by morphological observation, crystalline property analysis, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The LCMNO nanocomposite shows a superior discharge capacity of ca. 290 mAh g⁻¹ at low C-rates, due to a greater number of active sites embedded by nanostructured carbon species. In contrast, the carbon-coated LCMNO shows higher discharge capacity in high rate regions due to the carbon-coated layer in the carbon-coated LCMNO, suppressing the side reactions and enhancing the electrical conductivity.     

Synthesis and characterization of high-density non-spherical Li(Ni1/3Co1/3Mn1/3)O2 cathode material for lithium ion batteries by two-step drying method

Non-spherical Li(Ni_1/3Co_1/3Mn_1/3)O₂ powders have been synthesized using a two-step drying method with 5% excess LiOH at 800 °C for 20 h. The tap-density of the powder obtained is 2.95 g cm⁻³. This value is remarkably higher than that of the Li(Ni_1/3Co_1/3Mn_1/3)O₂ powders obtained by other methods, which range from 1.50 g cm⁻³ to 2.40 g cm⁻³. The precursor and Li(Ni_1/3Co_1/3Mn_1/3)O₂ are characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscope (SEM). XPS studies show that the predominant oxidation states of Ni, Co and Mn in the precursor are 2⁺, 3⁺ and 4⁺, respectively. XRD results show that the Li(Ni_1/3Co_1/3Mn_1/3)O₂ material obtained by the two-step drying method has a well-layered structure with a small amount of cation mixing. SEM confirms that the Li(Ni_1/3Co_1/3Mn_1/3)O₂ particles obtained by this method are uniform. The initial discharge capacity of 167 mAh g⁻¹ is obtained between 3 V and 4.3 V at a current of 0.2 C rate. The capacity of 159 mAh g⁻¹ is retained at the end of 30 charge-discharge cycle with a capacity retention of 95%.     

Magnesium ferrite nanoparticles as a magnetic sorbent for the removal of Mn2+, Co2+, Ni2+ and Cu2+ from aqueous solution

The aim of this research was to prepare magnesium ferrite (MgFe₂O₄) magnetic nanoparticles and to investigate their sorption characteristics towards Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ ions in aqueous solution. MgFe₂O₄ was synthesized by glycine-nitrate combustion method and was characterized by low crystallinity with crystallite size of 8.2?nm, particle aggregates of 13–25?nm, BET surface area of 14?m²/g and pore size of 8.0?nm. Sorption properties of MgFe₂O₄ towards Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ ions were studied using one-component model solutions and found to be dependent on metal ions concentration, contact time, pH and conditions of regeneration experiment. The highest sorption capacity of MgFe₂O₄ was detected towards Co²⁺ (2.30?mmol?g¹) and Mn²⁺ (1.56?mmol?g^?1) and the lowest towards Ni²⁺ (0.89?mmol?g^?1) and Cu²⁺ (0.46?mmol?g^?1). It was observed that sorption equilibrium occurs very quickly within 20–60?min. The pH_zpc of sorbent was calculated to be 6.58. At studied pH interval (3.0–7.0) the sorption capacity of MgFe₂O₄ was not significantly affected. Regeneration study showed that the metal loaded sorbent could be regenerated by aqueous solution of 10^?3 M MgCl₂ at pH 6.0 within 120?min of contact time. Regeneration test suggested that MgFe₂O₄ magnetic sorbent can be efficiently used at least for four adsorption-desorption cycles. The high sorption properties and kinetics of toxic metal ion sorption indicates good prospects of developed sorbent in practice for wastewater treatment.     

Performance of LiNi1/3Co1/3Mn1/3O2 prepared from spent lithium-ion batteries by a carbonate co-precipitation method

Spherical LiNi_1/3Co_1/3Mn_1/3O₂ cathode particles were resynthesized by a carbonate co-precipitation method using spent lithium-ion batteries (LIBs) as a raw material. The physical characteristics of the Ni_1/3Co_1/3Mn_1/3CO₃ precursor, the (Ni_1/3Co_1/3Mn_1/3)₃O₄ intermediate, and the regenerated LiNi_1/3Co_1/3Mn_1/3O₂ cathode material were investigated by laser particle-size analysis, scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS), thermogravimetry–differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), inductively coupled plasma–atomic emission spectroscopy (ICP-AES), and X-ray photoelectron spectroscopy (XPS). The electrochemical performance of the regenerated LiNi_1/3Co_1/3Mn_1/3O₂ was studied by continuous charge–discharge cycling and cyclic voltammetry. The results indicate that the regenerated Ni_1/3Co_1/3Mn_1/3CO₃ precursor comprises uniform spherical particles with a narrow particle-size distribution. The regenerated LiNi_1/3Co_1/3Mn_1/3O₂ comprises spherical particles similar to those of the Ni_1/3Co_1/3Mn_1/3CO₃ precursor, but with a narrower particle-size distribution. Moreover, it has a well-ordered layered structure and a low degree of cation mixing. The regenerated LiNi_1/3Co_1/3Mn_1/3O₂ shows an initial discharge capacity of 163.5 mA h g^?1 at 0.1 C, between 2.7 and 4.3 V; the discharge capacity at 1 C is 135.1 mA h g^?1, and the capacity retention ratio is 94.1% after 50 cycles. Even at the high rate of 5 C, LiNi_1/3Co_1/3Mn_1/3O₂ delivers the high capacity of 112.6 mA h g^?1. These results demonstrate that the electrochemical performance of the regenerated LiNi_1/3Co_1/3Mn_1/3O₂ is comparable to that of a cathode synthesized from fresh materials by carbonate co-precipitation.     

Microstructure,phase, magnetic properties,and electromagnetic wave absorption of graphene oxide – Ni0.7Zn0.3Fe2O4 – Al2O3 aerogel

In this work, an ultralight nanocomposite of graphene oxide aerogels as a matrix and nickel-zinc ferrite (Ni_0.7Zn_0.3Fe₂O₄) nanoparticles as a second phase for the absorption of electromagnetic waves in the frequency of 1–18 GHz were fabricated by the hydrothermal - freeze-drying method. α-Al₂O₃ nanoparticles were used for further impedance matching for applications in electromagnetic wave absorption. XRD, SEM, EDS, and VNA analyses were used to characterize the sample. The effects of the amount of Ni_0.7Zn_0.3Fe₂O₄ (NZF) nanoparticles (GO: NZF volume percent ratio = 5:1 and 2:1) on the absorption of electromagnetic waves were investigated.     

Polyaniline (PANI)–Co0.5Mn0.5Fe2O4 nanocomposite: Synthesis,characterization and magnetic properties evaluation

Polyaniline (PANI)/Cobalt-manganese ferrite, (PANI)/Co_0.5Mn_0.5Fe₂O₄, nanocomposite was synthesized by oxidative chemical polymerization of aniline in the presence of ammonium peroxydisulfate (APS). Microwave assisted synthesis method was used for the fabrication of core CoFe₂O₄ nanoparticles. The structural, morphological, thermal and magnetic properties of the nanocomposite were investigated in detail by X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The average crystallite size of (PANI)/Co_0.5Mn_0.5Fe₂O₄ nanocomposite by the line profile method was 20±9 nm. The magnetization measurements revealed that (PANI)/Co_0.5Mn_0.5Fe₂O₄ nanocomposite has superparamagnetic behavior with blocking temperature higher than 300 K. The saturation magnetization of the composite is considerably low compared to that of CoFe₂O₄ nanoparticles due to the partial replacement of Co²⁺ ions and surface spin disorder. As temperature decreases, both coercivity and strength of antiferromagnetic interactions increase which results in unsaturated magnetization of the nanocomposite.     

A simple and effective method to synthesize layered LiNi0.8Co0.1Mn0.1O2 cathode materials for lithium ion battery

Nanocrystalline materials of Ni_0.8Co_0.1Mn_0.1(OH)₂ are successfully synthesized by fast co-precipitation method. The crystalline structure and morphology of the precursors and LiNi_0.8Co_0.1Mn_0.1O₂ materials are characterized by XRD, SEM and Rietveld refinement analyses. It is found that the nanocrystalline phase and low crystallinity of Ni_0.8Co_0.1Mn_0.1(OH)₂ could help achieve its uniform mixing with lithium source, and further attribute to highly ordered layered LiNi_0.8Co_0.1Mn_0.1O₂ with low cation mixing degree. Electrochemical studies confirm that the LiNi_0.8Co_0.1Mn_0.1O₂ exhibits a good electrochemical property with initial discharge specific capacity of 192.4 mAh g^− 1 at a current density of 18 mA g^− 1, and the capacity retention after 40 cycles is 91.56%. This method is a simple and effective method to synthesize cathode material.     

Hierarchical spinel NixCo1-xFe2O4 microcubes derived from Fe-based MOF for high-sensitive acetone sensor

Hierarchically spinel Ni_xCo_1-xFe₂O₄ (0.0?≤?x?≤?0.5) microcubes were successfully prepared through a combined solvent evaporation strategy and morphology-inherited annealing treatment. By using the Fe-based metal-organic frameworks (MOFs), Fe₄(Fe(CN)₆)₃, and inorganic Ni²⁺and Co²⁺ acetate salts as co-templated precursors, hierarchical Ni-doped spinel CoFe₂O₄ architecture can be obtained, and the Ni/Co substitution ratios can be controlled systematically. The obtained cubic hierarchical Ni_xCo_1-xFe₂O₄, (0.0?≤?x?≤?0.5) composites presented highly acetone sensing properties, among which the Ni_0.1Co_0.9Fe₂O₄ composite showed the strongest response performance (with gas response (R_g/R_a) of 1.67 at 240?°C) and excellent reproducibility (for at least 14 cycles), and the proposed acetone sensing mechanism was also discussed. The presented solvent evaporation and co-templated strategy may allow precisely access to fabricating other heteroatom doped inorganic materials with intriguing morphologies, architectures, chemical compositions and tunable sensing properties.     

Effect of fluorine in the preparation of Li(Ni1/3Co1/3Mn1/3)O2 via hydroxide co-precipitation

Uniform and spherical Li(Ni_1/3Co_1/3Mn_1/3)O_(2−δ)F_δ powders were synthesized via NH₃ and F⁻ coordination hydroxide co-precipitation. The effect of F⁻ coordination agent on the morphology, structure and electrochemical properties of the Li(Ni_1/3Co_1/3Mn_1/3)O_(2−δ)F_δ were studied. The morphology, size, and distribution of (Ni_1/3Co_1/3Mn_1/3)(OH)_(2−δ)F_δ particle diameter were improved in a shorter reaction time through the addition of F⁻. The study suggested that the added F improves the layered characteristics of the lattice and the cyclic performance of Li(Ni_1/3Co_1/3Mn_1/3)O₂ in the voltage range of 2.8-4.6 V. The initial capacity of the Li(Ni_1/3Co_1/3Mn_1/3)O_1.96F_0.04 was 178 mAh g⁻¹, the maximum capacity was 186 mAh g⁻¹ and the capacity after 50 cycles was 179 mAh g⁻¹ in the voltage range of 2.8-4.6 V.     

Synthetic optimization of spherical Li[Ni1/3Mn1/3Co1/3]O2 prepared by a carbonate co-precipitation method

A carbonate co-precipitation method was employed to prepare spherical Li[Ni_1/3Co_1/3Mn_1/3]O₂ cathode material. The precursor, [Ni_1/3Co_1/3Mn_1/3]CO₃, was prepared using ammonia as chelating agent under CO₂ atmosphere. The spherical Li[Ni_1/3Co_1/3Mn_1/3]O₂ was prepared by mixing the precalcined [Ni_1/3Co_1/3Mn_1/3]CO₃ with LiOH followed by high temperature calcination. The preparation conditions such as ammonia concentration, co-precipitation temperature, calcination temperature and Li/[Ni_1/3Co_1/3Mn_1/3] ratio were varied to optimize the physical and electrochemical properties of the prepared Li[Ni_1/3Co_1/3Mn_1/3]O₂. The structural, morphological, and electrochemical properties of the prepared LiNi_1/3Co_1/3Mn_1/3O₂ were characterized by XRD, SEM, and galvanostatic charge-discharge cycling. The optimized material has a spherical particle shape and a well ordered layered structure, and it also has an initial discharge capacity of 162.7 mAh g^− 1 in a voltage range of 2.8-4.3 V and a capacity retention of 94.8% after a hundred cycles. The optimized ammonia concentration, co-precipitation temperature, calcination temperature, and Li/[Ni_1/3Co_1/3Mn_1/3] ratio are 0.3 mol L^− 1, 60 °C, 850 °C, and 1.10, respectively.