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Summary: This paper reports a feasible approach to offer LiNi0.8Co0.1Mn0.1O2 (NCM811) layered cathode materials with enhanced lattice ordering and improved electrochemical performance through a nano grinding assisted solid‐state reaction. Different from the commercial precursor method, oxide raw materials, NiO, CoO and MnO2, rather than the hydroxides, was employed as the starting raw material which was milled into submicron size, pressed into pellets and crushed into granular powder. After calcination under oxygen atmosphere under different temperature, such a simple approach provides layered cathode materials with controllable Li/Ni disordering. Powder XRD results show that when sintered at 800°C, a largest I(003)/I (104) ratio is observed, indicating that the cationic disordering is the lowest, as been confirmed by the XRD refinement data, showing that only 1.08% Ni is misplaced at 3b site. For the electrochemical test, the pNCM800 sample presented an initial specific discharge capacity of 203 mAh/g at 0.1C, together with a capacity retention of 91.77% after 100 cycles at 0.5C. Compared to the value of the sample obtained at normal routine (163.8 mAh/g and 74.85%), the improvement in electrochemical behavior is obvious. Furthermore, the rate performance is also improved, with a specific capacity of 144.1 mAh/g even at 5C rate. The reason for such enhancement could be ascribed to the better kinetic process with low interfacial resistance and fast Li diffusion contributed from the promoted lattice ordering. The results obtained in the experiments greatly indicate the significance of the approach in controlling the Li/Ni disordering, and thus offer an alternative routine for the mass production of layered cathode materials besides the so‐called precursor method. [ABSTRACT FROM AUTHOR]

Na3–2xMgxV2(PO4)3/C (0 ≤ x ≤ 0.2) were synthesized by a sol–gel method. According to X-ray diffraction (XRD) Rietveld refinement and energy dispersive spectroscopy (EDS) mapping results, Mg ions were approved to occupy the Na2 (18e) site in Na3–2xMgxV2(PO4)3/C for the first time. The amount of Mg substitution in Na3–2xMgxV2(PO4)3/C was optimized. The specific discharge capacities of Na2.9Mg0.05V2(PO4)3/C at 10 C, 20 C, and 30 C were 98.9%, 91.5%, and 76.2% of the value obtained at 1 C, respectively. Na2.9Mg0.05V2(PO4)3/C exhibited the highest capacity retention of 80.3% with a discharge capacity of 77.3 mAh·g−1 after 1200 cycles at 10 C. Na2.9Mg0.05V2(PO4)3/C exhibited superior rate performance, resulting from a high sodium diffusion coefficient (DNa) of 3.91 × 10–12 cm2·s−1 and the excellent electrical conductivity (5.7 × 10–2 s·cm−1). Combining the X-ray photoelectron spectroscopy (XPS) and Electrochemical impedance spectroscopy (EIS) results, the mechanism of Mg substitution was investigated. Since two Na+ were replaced by one Mg2+, V Na ′ was produced to maintain valence equilibrium. This phenomenon benefited Na+ migration by broadening the diffusion channel in the structure of Na3V2(PO4)3. According to the EPR results, the signal intensity of Na2.9Mg0.05V2(PO4)3/C was much stronger than that of Na3V2(PO4)2/C, thus confirming the existence of V Na ′ after Mg substitution. When the amount of Mg substitution was further increased to 0.1, the DNa decreased because of the small radius of Mg2+, which led to severe lattice distortion and volumetric shrinkage of the unit cell. [ABSTRACT FROM AUTHOR]

Boron-modified Li(Ni0.8Co0.1Mn0.1)1−xBxO2 cathode materials(NCM811) were successfully prepared by a nano-milling assisted solid-state approach. X-ray diffraction investigations showed that the materials are solid solutions with a layered structure. SEM observations implied that the doped B ions promoted the growth of the target crystal with well-developed facets since it will form liquid phase at lower temperature. The intensity ratio of I(003)/I(104) raised with the increase in Boron doping concentration, until a maximum value of 1.453 was observed at x = 0.01. Further Rietveld refinements revealed that boron ions occupy the crystal lattice in the transition metal slab which helps to promote the lattice ordering by decreasing the Li/Ni ionic mixing. Such B promoted NCM811 cathode materials were confirmed to have an improved diffusion coefficient with a reduced interfacial resistance by subsequent CV and EIS measurements. From the electrochemical test, those B modified NCM811 cathode materials presented enhanced electrochemical performance. Among the synthesized samples, Li(Ni0.8Co0.1Mn0.1)0.99B0.01O2 exhibited the best specific capacity, with 194.7 mAh g−1 and 166.8 mAh g−1 at 0.1C and 5C respectively. The capacity retention at 0.5C was also confirmed as 98.2% after 100 cycles. Such improvement can be explained by the reduced Li/Ni ionic mixing, the increased Li ionic diffusion and the reduced interfacial resistance caused by the promoted growth of the B doped NCM811 crystals. Compared to those NCM811 materials reported elsewhere, the material obtained by this approach showed high potential for future application. [ABSTRACT FROM AUTHOR]

A strategy to enhance the electrochemical performance of a single-crystal LiNi x Mn y Co z O 2 (NCM) electrode is proposed herein based on a preferred orientation of a Li diffusion pathway along the working direction under an ordinary 0.4-T magnetic field. Hexagonal NCM622 single crystals can be aligned along their crystallographic c-axis parallel to the applied magnetic field because the crystal has an easy magnetization axis along the c-axis. The horizontal magnetic field–oriented NCM622 cathode (HMFC) shows inhibited polarization and increased lithium-ion conductivity. The suppressed polarization promotes cyclability, increasing the specific capacity from 157.93 to 168.75 mAhg−1 after the 100th cycle at 0.5 C. Furthermore, the increased diffusion coefficient (from 3.06 × 10−10 cm2s−1 to 7.12 × 10−10 cm2s−1) causes substantial improvement in the rate performance, achieving a high specific capacity of 130.77 mAhg−1 at 10 C, while the electrode without magnetic treatment achieves a specific capacity of only 115.88 mAhg−1. Owing to such a superior electrochemical performance, the HMFC electrodes show high potential for lithium-ion batteries in the EV industry. Decreasing the magnetic field from 6 to 0.4 T for cathode alignment facilitates the applicability of the proposed strategy to production lines of battery plants using commercially available permanent magnets because a magnetic field of 0.4 T is easily achievable. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Li 2 Ni 0.5 Mn 1.5 O 4 (LNMO) cathode releases a high capacity of 260.4 mAh g−1. • The surface of LNMO cathode is covered by a thin LBSO layer in this approach. • LBSO layer suppresses the increase in resistance and the degradation in Li diffusion. • Capacity retention is significantly improved by 14% due to the LBSO coating. A new spinel Li 2 Ni 0.5 Mn 1.5 O 4 (LNMO) cathode reported in our previous work displays high initial specific capacity (260.4 mAh g−1) and good coulombic efficiency (92.2%), but suffers from low capacity retention of 80.2% after 50 cycles. In this paper, Li 2 O-0.2B 2 O 3 -1.8SiO 2 (LBSO) glass phase surface modification is adopted to promote the electrochemical performance of LNMO. LBSO layer coated on the surface of LNMO cathode, as confirmed by SEM and HRTEM observation, can effectively prevent the cathode from dissolving in the electrolyte, therefore suppresses the increase in resistance and the degradation in Li-ions diffusion. Consequently, the electrochemical properties of the surface modified cathode material are improved. The initial specific capacity of 0.3 wt% LBSO coated LNMO is kept as 263 mAh g−1 with coulombic efficiency of 95%. Notably, the capacity retention after 100 cycles is improved from 69% to 83% by a comparison between the pristine and coated samples. Moreover, the coated cathode exhibits good rate performance, giving high specific capacity of 142 mAh g−1 even at a current density of 5C. All the results presented above suggest high potential for the material as candidate cathode for high energy density batteries. [ABSTRACT FROM AUTHOR]

Although the Ni-rich LiNi 0.8 Co 0.15 Al 0.05 O 2 (N85CA) material has been used as the commercial cathode of electric vehicle battery, the instability of the layered structure and the short lifespan under high voltage cycling prevent its practical application to higher energy density. Herein, Nb-doped N85CA material, with enhanced structural stability and improved cycle stability, is reported to work at 4.5V. In particular, Nb0.5%-N85CA shows the best electrochemical performance, with a discharge capacity of 200.2 mAh/g at 0.1C, and a retention of 94.19% after 100 runs at 0.5 C. As a comparison, the data of the pristine N85CA are 210.2 mAh/g and 69.46%, respectively. Such an obvious increase in the capacity retention is caused by the promoted lattice stability provided by the strong Nb–O bond that inhibits the H2–H3 phase transition in the electrochemical process. The incorporation of Nb5+ ions further increases the interslab thickness that enable a rapid migration of Li ions (2.23 × 10−10 S cm−1 vs. 8.32 × 10−11 S cm−1), and the rate behavior of the cathode is also enhanced. Furthermore, Nb0.5%-N85CA material displays a specific capacity of 156.2 mAh/g at 5 C, while that of the pristine N85CA is 123 mAh/g. The results strongly indicate that such Nb-doped N85CA material has high potential as a cathode candidate, especially for high energy applications. [ABSTRACT FROM AUTHOR]

New anode materials (Co x /Li 3 Ti 4 Co 1−x CrO 12 ) had been successfully prepared via a high temperature solid-state method. Pure phase Co-Cr replaced solid solution (Li 3 Ti 4 CoCrO 12 ) was obtained by calcinating the precursor under air atmosphere while the Co modified solid solutions (Co x /Li 3 Ti 4 Co 1−x CrO 12 ) were prepared under a reducing atmosphere. Various methods, such as XRD, SEM, EDX mapping, cyclic testing, EIS, CV, XPS and EPR were employed to characterize the powder samples and investigate their electrochemical behavior. SEM results showed spherical shape of the products with nano sized primary crystals. EDX mapping further confirmed the different existence of the Co element, uniform distribution of Co 2+ ions within the spinel lattice and separated metallic Co on the particle surface. Cyclic tests revealed that the Co modified samples showed great promotion in their electrochemical performance. For the sample with x = 0.1, the best results with an initial capacity of 157.6 mA h/g and a capacity retention of 96.4% after 100 runs were observed. Such promotion can be explained by the improved electronic conductivity and enhanced Li + diffusion coefficient confirmed by the EIS and CV simulation, which was caused by the oxygen vacancy produced during the calcination under the reducing atmosphere. [ABSTRACT FROM AUTHOR]

• A novel approach of synthesizing Li-rich cathode materials in oxygen atmosphere. • Li/Ni disordering and electrochemical polarization were reduced when synthesizing in O 2. • Improved capacity retention of 93.63% is achieved for LNCMA-O 2 sample. • High rate performance of 113.4 mAh g−1 at 5 C is observed for LNCMA-O 2 sample. Mn-based Lithium-rich cathode materials suffer from poor cycle stability and rapid voltage decay during the cycling, which are the main bottlenecks inhibiting their applications. In this work, a new method for synthesizing of Li 1.4 Mn 0.61 Ni 0.18 Co 0.18 Al 0.03 O 2.4 (LMNCA) cathode material in oxygen (LMNCA-O 2) atmosphere is presented. The effects of synthesis atmosphere on the structural changes are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Rietveld refinement. As a result, the LMNCA-O 2 material displays a lower Li/Ni disordering (Ni in Li Layer: 6.76%) and reduced amount of Li 2 MnO 3 phase than that of the material synthesized in air (LMNCA-air), which can be attributed to the increased Ni3+ (55.925%) cations in the compound, as confirmed by XPS. LNCMA-O 2 displays a high initial specific capacity of 229.1 mAh g−1 at 0.5 C in the potential range of 2.0–4.8 V and superior capacity retention of 93.63% after 100 cycles at 0.5 C. Additionally, good rate performance of 113.4 mAh g−1 at 5 C is also achieved for LNCMA-O 2 cathode material when compared to that of 74.1 mAh g−1 for the LNCMA-air sample. The above findings obtained in the present approach offered a novel method for synthesizing the cathode material in a different way rather than the precursor approach. [ABSTRACT FROM AUTHOR]

Better electrochemical properties of lithium batteries are achieved by a two-step solid state method with Y 2 O 3 protective layer coated on Li 1.4 Mn 0.61 Ni 0.18 Co 0.18 Al 0.03 O 2.4 (LNCMA) layered cathode material to meet the new requirements. XRD, TEM and various electrochemical investigations are used to reveal the fine structure and electrochemical behavior of the prepared Y 2 O 3 /LNCMA materials. The result indicates that Y 2 O 3 layer covers the surface of the LNCMA cathode in our approach. Although Y 2 O 3 coated LNCMA displays slight decrease in the initial capacity when compared with the original Li rich phase, the cathode with 3 wt% Y 2 O 3 coating shows promoted cyclability with 92.9% capacity retention after 100 cycles at 0.2C and an improved rate behavior of 124.1 mAh g−1 even at 10C. Such an obvious increase in electrochemical behavior can be explained by the reduced interfacial resistance and increased ionic diffusion which caused by the suppressed transition metal dissolution in the electrolyte, as confirmed from the impedance spectra. The above results greatly suggest that Y 2 O 3 /LNCMA material can be applied as a potential cathode in LIBs with high energy. • Y 2 O 3 layer is formed on the surface of Li rich cathode in this approach. • Y 2 O 3 serves as protective coating to suppress the dissolution of transition metal. • A capacity retention of 92.9% is achieved due to the surface Y 2 O 3 coating. • An improved rate behavior of 124.1 mAh g−1 is observed at 10C after coating with Y 2 O 3. [ABSTRACT FROM AUTHOR]

In order to enhance cycling stability, Rb + has been incorporated into Li-rich manganese based layered oxide cathode materials for lithium-ion batteries (LIBs) by a co-precipitation method and a subsequent solid-state reaction. The influence of the content of Rb + in the cathodes on the performance was investigated and the optimal content was identified to be x = 0.03. The inter-slab distance exhibited a slight increase after the Rb + incorporation, which reduced the energy barrier for the intercalation/deintercalation process of Li + in the cathode. Electrochemical characterization showed that the as-synthesized cathode materials have an improved cycleability and rate performance compared with the pristine Li-rich manganese layered oxide based cathodes for LIBs. In addition, it was confirmed that the Rb + doping clearly suppresses the process of the simultaneous lithium extraction along with oxygen activation at the high voltage region which could alleviate the irreversible loss of oxygen in the form of Li 2 O. The improved diffusion coefficient of Li ions in the Rb + incorporated cathodes was confirmed by electrochemical impedance spectroscopy measurements. [ABSTRACT FROM AUTHOR]