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Lithium-rich layered oxides with high energy density have been intensively investigated as advanced lithium-ion batteries cathode materials. However, capacity degradation and voltage decay caused by irreversible lattice oxygen loss and structural transformation during cycling restrict their application. Herein, we proposed a high valance cations Nb5+ doping strategy and synthesized a series of Li1.2Mn0.54-x/3Ni0.13-x/3Co0.13-x/3NbxO2 (x = 0, 0.01, 0.02 and 0.03) cathode materials. The effects of Nb5+ doping on crystallographic structure and electrochemical property were systematically studied. In virtue of the large ionic radii and strengthened Nb–O bonds, the doped samples present commendable structural stability and expanded interlayer spacing for Li-ions migration, which ensures the upgraded cyclic stability and rate performance. In particular, the electrode with x = 0.02 delivers a discharge specific capacity of 265.8 mAh g-1 at 0.2 C with decelerated voltage decay, while 86.9% capacity are remained after long-term cycles. Moreover, excellent discharge specific capacity of 153.4 mAh g−1 is still attained at 5 C accompanied with enhanced Li-ion diffusion kinetics.

MoS2 is currently under intensive research as a potential candidate for energy storage applications because of its high theoretical capacity. However, unmodified MoS2 suffers from inferior rate capability and poor long-term cycling stability. Inspired by a hornet making a nest and the favorable shape and structural strength of a honeycomb, a composite with a three-dimensional highly porous sandwiched honeycomb structure has been successfully prepared for the first time. Its novel structure originates from anchoring self-assembled flower-like porous MoS2 slices (MoS2-FPSs) on layer-by-layer reduced graphene oxide (rGO)–carbon nanotubes (CNTs) with the assistance of an ionic liquid (IL). The MoS2 ultrathin nanosheets are self-assembled to form MoS2-FPSs and then co-assembled with rGO and CNTs to generate a hierarchical porous structure. By virtue of this novel superstructure, the electrode demonstrates remarkable electrochemical properties with a high initial capacity (1456 mA h g−1) and an enhanced high rate capability (712 mA h g−1 at 5 A g−1), as well as one of the best long-term cycling stabilities with a capacity decay as low as 0.0075% per cycle (745 mA h g−1 at 5 A g−1 after 1000 cycles), confirming its potential application in high-performance lithium-ion batteries.

Rational morphology design and size control have been demonstrated an effective strategy to improve the electrochemical performance of cathode materials for lithium ion batteries. In this work, different morphologic Li-rich layered cathode materials Li1.2Mn0.54Ni0.13Co0.13O2 with hierarchical structures are conveniently synthesized through a facile solvothermal route followed by calcination treatment. The morphology and size of the as-prepared precursors are easily regulated by changing the addition of organic solvent with different viscosity and polarity. And their critical impacts on the microstructure and electrochemical property of Li-rich layered electrodes are further systematically investigated. In particular, the hierarchical structured Li1.2Mn0.54Ni0.13Co0.13O2 microspheres exhibit superior electrochemical performance and excellent cycling stability among all samples, delivering a discharge capacity of 281.9 mAh g−1 at 0.1 C with 84.8% retention after 100 cycles. A high discharge capacity of 143.0 mAh g−1 still can be achieved even at a high current density of 5 C. Besides, this work would also provide an effective and feasible strategy for the morphology controllable synthesis of high energy density oxide electrode materials for lithium ion batteries.

The sol-freeze-drying method is successfully applied to tune the structure of Co-free Li-rich Mn-based layered material (Li1.2Mn0.6Ni0.2O2). The structure, morphology and electrochemical performances of the tuned materials are compared with its counterpart prepared by traditional sol-gel method. The results confirm that sol-freeze-drying method is an effective approach to homogenize the transition metal distribution in Li1.2Mn0.6Ni0.2O2 without surface segregation of Ni. The specific capacity of Li1.2Mn0.6Ni0.2O2 synthesized by sol-free-drying method is 232 mAh g−1 after 100 cycles at 0.2C with 96% of initial discharge capacity retained. It is much higher than the 182 mAh g−1 of Li1.2Mn0.6Ni0.2O2 prepared by sol-gel method with poor capacity retention of 79%. Li1.2Mn0.6Ni0.2O2 synthesized by sol-free-drying method delivers the capacities of 252, 220, 192, 148, and 84 mAh g−1 at rates of 0.1C, 0.5C, 1C, 2C, and 5C, respectively. Besides, impedance spectroscopy shows that the charge-transfer resistance of Li1.2Mn0.6Ni0.2O2 synthesized by sol-free-drying method after 20 cycles increases from 43 Ω to 51 Ω, which is much lower than that of Li1.2Mn0.6Ni0.2O2 prepared by sol-gel method from 42 Ω to 78 Ω.

Peapod-like ZnO@C with internal void space has been synthesized by calcination of ZnO/ZnOHF@polydopamine nanorods. By designing both the large void space between particles and external elastic carbon shell, the large volume change of ZnO during charge-discharge process could be effectively relieved. Moreover, the carbon shell functioned as an electronic conductor and elastic barrier, could accelerate the reaction kinetics and confine stable SEI films formation on the outer protective layer to further improve the structural integrity. Benefiting from these structure advantages, the peapod-like ZnO@C presents a prominent electrochemical performance with a retained discharge capacity of 565.1 mAh g-1 at 0.2 A g-1 and high rate capacity of 246.6 mAh g-1 even at 4 A g-1.

Integrating high-capacity MoS2 with carbon materials, especially graphene, into a rationally designed structure has been demonstrated an effective strategy to construct anode materials with superior electrochemical performance for application in lithium ion batteries (LIBs). Here, a rationally designed 3D MoS2/dual-channel graphene framework (MoS2/GA–GF) hybrid has been constructed through a two-step method. This dual-channel graphene framework (GA–GF) consists of two types of channels with different graphene types, graphene foam channels improving electron transport and graphene aerogel channels facilitating Li ion diffusion. With this structure, the MoS2/GA–GF hybrid can efficiently improve electron and Li ion transport kinetics and accommodate the MoS2 volume change during cycling. Benefiting from the above merits, the MoS2/GA–GF electrode as a free-standing electrode presents a high initial capacity (1404 mA h g−1) with a high initial coulombic efficiency (81.7%), excellent rate capability (593 mA h g−1 at 5 A g−1) and a superior long-term cycling stability (843 mA h g−1 at 1 A g−1 after 500 cycles) when evaluated as an LIB anode. Therefore, the GA–GF as a support and current collector is expected to be ideal for application in LIBs and other electrochemical energy storage devices.

Here, we designed a facile solvothermal method to prepare Li1.2Ni0.13Co0.13Mn0.54O2 hollow microspheres with considerable uniformity and monodispersity. In this method, lithium ions and transition metal carbonate have been simultaneously precipitated in the ethanol-polyethylene glycol mixed solvent system to form carbonate precursors, which subsequently transform into self-assembled hollow microspheres by a heat treatment. As cathode material for lithium ion batteries, its unique structure makes for sufficient contact between electrode and electrolyte to provide more reaction sites and shorter paths for Li+ transportation, contributing to remarkable cycling stability and excellent rate capability with improved electrochemical kinetics properties. Specifically, Li1.2Ni0.13Co0.13Mn0.54O2 hollow microspheres achieve a high initial discharge capacity of 287 mAh g−1 at 0.1 C and 234 mAh g−1 at 1 C, with capacity retentions of 85.7% and 81.3% after 100 cycles, respectively. Besides, it exhibits a high rate capacity of 150 mAh g−1 even at 5 C. Moreover, the present synthesis method could also provide an effective and promising strategy for the preparation of high energy density cathode materials for lithium ion batteries.

Lithium-rich layered oxides (LLOs) are considered as the most promising candidate for the cathode of high energy density lithium-ion batteries. However, the poor cycle stability especially under high temperature is hindering its practical applications. Herein, a full concentration gradient LLO with spinel modification is designed and prepared. This synergistic strategy not only makes full use of high Ni content that improving the discharge voltage but also mitigates the detrimental influence of surface residual alkalis. The surface spinel modified cathode exhibits a higher initial coulombic efficiency of 87.52% with enhanced cycle stability at 55 °C (191.5mAh/g after 200 cycles at 1C), the average discharge voltage drop is also alleviated to 3.17 mV per cycle (at 55 °C). Furthermore, it also shows enhanced thermal stability, in which the exothermic onset temperature rises from 265.380 to 295.221 °C, and the thermal release decreases from 211.525 to 181.181 J/g. This work proposes an integrated strategy to enhance the comprehensive performance of LLOs, thus shed a light on the way for its practical application.

Mesoporous nano-microparticles lithium-rich Zn-doped Li1.2Mn0.54Co0.13Ni0.13O2 cathode materials have been synthesized by utilizing the structural characteristics of metal–organic frameworks. The electrochemical performance is improved by the substitution of an appropriate amount of Zn into the layered Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 cathode material.

Lithium-rich layered cathode materials recently arouse highly attention for the high discharge capacities over conventional cathode materials, but trapped for severe voltage decay, poor cycling stability and inferior rate performance upon cycling. In this work, introducing Cs ions into the Li layer is employed to prepare Cs+-doped cathode material Li1.2Mn0.54Ni0.13Co0.13O2 via a simple sol-gel method and a subsequent calcination process. The Cs+ − doped sample exhibits much enhanced electrochemical performances in comparison with that of pristine sample, especially the rate capability (171.1 mAh g−1 compared to 150.2 mAh g−1 at 5C). Meanwhile, the Cs-doped one reaches an initial discharge capacity of 247.4 mAh g−1 with improved initial Coulombic efficiency of 86.0% at 0.2C rate and outruns for 177.9 mAh g−1 of discharge capacity after 100 cycles at 0.5C. Additionally, it is observed that the Cs+- doped sample has a well-defined layered structure and an expanded Li slab space caused by the Cs+ accommodation, which provides facile Li+ diffusion paths and reduces the energy barrier of the Li+ insertion/extraction in the crystal lattice. More importantly, the Cs doping is in favor of stabilizing the crystal structure and meanwhile restraining the decrease of discharge voltage by alleviating the phase transition of layered to spinel structure upon cycling, thus greatly contributing to the better electrochemical performances.

Lithium-rich layered Li1.2Ni0.13Co0.13Mn0.54O2 cathode materials have been successfully fabricated by a glucose-assisted combustion method combined with a calcination treatment. The effect of the amount of glucose fuel on the properties of the prepared materials is investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements. The results show that the nano-sized cathode material obtained at a fuel ratio of φ = 1 exhibits uniform fine well-crystallized particles with the largest specific surface area, leading to excellent cyclic capability and rate performance. It delivers the highest initial discharge capacity of 280.5 mA h g−1 with a capacity retention of 84% after 50 cycles at 0.1C (25 mA g−1). Besides, after cycling at an increasing rate from 0.2C to 3C, the electrode retained 90.3% (230.2 mA h g−1) of the initial discharge capacity when the rate was recovered back to 0.2C.

N-doped porous carbon coated graphene (rGO) sheets (denoted as NPCGS) have been synthesized through a facile pyrolysis of an in situ grown zeolitic imidazolate framework (ZIF) on graphene oxide (GO). When tested as an anode material for lithium-ion batteries, the NPCGS exhibited superior electrochemical performance with a specific capacity of 1040 mA h g−1 after 200 cycles at a discharging current density of 0.5 A g−1 and excellent rate performance. The fascinating electrochemical performance of the NPCGS can be attributed to the synergistic effect of NPC and graphene in terms of N-doping, rich porosity and high electrical conductivity. The novel N-doped porous carbon coated graphene sheet material can be extended for application in sensors, electronic devices, catalysts, hydrogen storage and other systems.

Lithium-rich layered oxide cathode material Li1.2Ni0.13Co0.13Mn0.54O2 has been successfully synthesized via a self-template method followed with sol-gel reaction, microspheres consisting of three-dimensional (3D) nanothorn MnO2 are used as the template and Mn source. The as-prepared sample (denoted as LNCM-T) exhibits well-layered structure and high crystallinity, which is confirmed by XRD and HRTEM. The results of electrochemical performances show that the LNCM-T sample has excellent high-rate capability with a discharge capacity of 159.7 mA h g−1 at a current density of 1250 mA g−1. Besides, it delivers a high initial Coulombic efficiency of 84.3% with a discharge capacity of 243.8 mA h g−1 at room temperature. The remarkable cycling stability and excellent rate capability of LNCM-T sample are ascribed to the enhanced layered structural stability, short lithium-ion diffusion path and reduced charge transfer resistance.

In this study, both morphology-related factors and catalytic activity factors were taken into account simultaneously and sea urchin-like Co3O4 nanoneedles grown on nickel foam were synthesized via a facile hydrothermal strategy (grass-like Co3O4 were also prepared for comparison). Most noteworthy is that 3D open-structured sea urchin-like Co3O4 exposing more Co3+ sites with large specific surface area and abundant mesoporous structure exhibited superior electrocatalytic performance as compared to 1D structured grass-like Co3O4 and former reported 3D structured electrodes (i.e., urchin shaped, flower shaped). Pd decorated sea urchin-like Co3O4 was also prepared through a simple impregnation method. When served as binder/carbon-free catalytic cathode for Li-O2 batteries, the problems about limited capacity, large overpotential and poor cycle life were effectively improved. The catalytic electrode displayed a low overpotential of 1.12 V, high specific capacity (8819.2 mA h g−1) at a current density of 200 mA g−1 and long cycle life with the capacity limited at 500, 1500, 2500, even 3500 mA h g−1, overmatching most of the transition-metal-oxides based catalytic electrodes, which are intrinsically dependent on the characteristic design in both morphology and catalytic active sites of the electrodes.