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Lithium iron phosphate (LiFePO4) cathode materials were synthesized by the solvothermal method with the assistance of different surfactants. The influences of polyethylene glycol 2000 (PEG 2000), polyvinylpyrrolidone (PVP), and cetyltrimethyl ammonium bromide (CTAB) on the microstructure and electrochemical performance of LiFePO4 were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), electrochemical impedance spectroscopy (EIS), and charge/discharge measurements. The particle size of the LiFePO4 synthesized with the assistance of PEG was uniform and showed a flat rhombohedron-like shape. The initial discharge specific capacity is up to 122.80 mAh/g with an initial coulombic efficiency of 95.50% at 0.1C. LiFePO4 synthesized with PVP-assisted presents a porous structure with an initial discharge specific capacity of 91.01 mAh/g. LiFePO4 synthesized with CTAB-assisted shows a flower-like morphology with an initial discharge specific capacity of 100.44 mAh/g. Though the initial discharge capacities of the LiFePO4 materials prepared with the assistance of CTAB and PVP are lower than those of the LiFePO4 prepared without the assistance of surfactant, the two materials exhibited excellent cyclic stability at 0.1C.

Exploring nanostructured transition-metal sulfide anode materials with excellent electrical conductivity is the key point for high-performance alkali metal ion storage devices. Herein, we propose a powerful bottom-up strategy for the construction of a series of sandwich-structured materials by a rapid interfacial self-assembly approach. Oleylamine could act as a functional reagent to guarantee that the nanomaterials self-assemble with MXene. Benefiting from the small size of Co-NiS nanorods, excellent conductivity of MXene, and sandwiched structure of the composite, the Co-NiS/MXene composite could deliver a high discharge capacity of 911 mAh g-1 at 0.1 A g-1 for lithium-ion storage. After 200 cycles at 0.1 A g-1, a high specific capacity of 1120 mAh g-1 could be still remaining, indicating excellent cycling stability. For sodium-ion storage, the composite exhibits high specific capacity of 541 mAh g-1 at 0.1 A g-1 and excellent rate capability (263 mAh g-1 at 5 A g-1). This work offers a straightforward strategy to design and construct MXene-based anode nanomaterials with sandwiched structure for high-performance alkali metal ion storage and even in other fields.

A unique MoS2/graphene composite (MoS2/GrF) was synthesized via a facile hydrothermal method. XRD, FESEM, EDS, TEM, HRTEM, XPS, and BET analyses were performed to characterize the as-synthesized samples. The samples were demonstrated to present interesting uniform three-dimensional hierarchical heterogeneous structures where MoS2 microspheres (with an average diameter of 750 nm) penetrated the graphene layer. By the “space-confined” effect, the (002) plane of MoS2 is inhibited when grown in the interlayer of GO, which increases the interlayer spacing and improves the rate performance of the electrode. Moreover, MoS2 that grows between the graphene layers can form a good contact, reducing the contact resistance. As an anode material for lithium-ion batteries, the MoS2/GrF electrode exhibited an outstanding reversible capacity (1510 mAh g−1 at 100 mA g−1 after 200 cycles) and excellent rate performance (~990 mAh g−1 at 1000 mA g−1).

As high nickel ternary material is becoming more superior to other positive electrode material for its high-specific capacity and the characteristics of low cost, it has been widely researched recently, especially for the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material used in lithium-ion batteries, which lowers metal cobalt content in the precursors, thus greatly reduce the cost of the raw material. However, it is well known that with the increase of nickel, the “Li/Ni mixing” phenomenon becoming more and more obvious, leading to the NCM811 did very badly on electrochemical performance, especially for the cycle performance. In this paper, Mg-doped LiNi0.8−x MgxCo0.1Mn0.1O2 (x = 0, 0.01, 0.03, 0.05) material with good crystallinity and uniformed particles is synthesized by solvothermal and calcining method. The cation mixing effect was inhibited by a fact that the ionic radius of Mg2+ is closer to that of Ni2+ than that of Li+. Results showed that the first discharge specific capacity of doped material is 218 mAh·g−1 at the current of 18 mA/g(0.1 C), and the capacity retention is 87.3% after 100 cycles, which are improved at 38 mAh·g−1 and 12.3%, respectively, compared with pristine material. We attributed this improvement mechanism to the improvement of the order of layered structure in NCM811 by Mg doping, which provide the improvement of the structure in crystal dynamics.

V6O13 cathode materials have received great attention owing to its high theoretical specific capacity and energy density; however, the poor cycle stability and rate performance have constrained their development. In this experiment, the nanorod-like Co-doped V6O13 with a theoretical equation of CoxV6−xO13 was synthesized for the first time by one-step solvothermal method, and investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tests of electrochemical performances. When x = 0.03, the material shows the best electrochemical performance, the sample has the best discharge specific capacity of 377.3 mAh/g at the beginning, and the capacity retention is 54.4% after 100 cycles at 0.1 C (42 mA/g), comparing with those of the pure V6O13 only 279.4 mAh/g and 37.6% in the same condition. The increase in specific surface area and structural stability promoted the kinetics of the chemical reaction and improved the electrochemical properties of the material. The applicability of this method was further examined through a series of tests and analysis of disassembled batteries after cycle, and the evidences that proper Co doping can stable the structure of materials are provided.

LiNi0.8Co0.1Mn0.1O2 (NCM811), as one of the most promising cathode materials for lithium ion batteries, has gained a huge market with its obvious advantages of high energy density and low cost. It has become a competitive material among various cathode materials. However, in NCM811, the phenomenon of “cationic mixed discharge” is serious, resulting the cyclic performance performing badly. In addition, the thermal stability of ternary material will also be poor with the increase of nickel when temperature is high. In view of the above-mentioned situation, researchers come up with different methods to modify LiNi0.8Co0.1Mn0.1O2 by doping and coating to reduce mixing effect and improve its electrochemical performance. Here, we sketch out the structure, properties, and existing problems of NCM811 and summarize some cutting-edge modification methods. Finally, the development direction and commercial application of NCM811 cathode materials are prospected to accelerate its commercialization process.

As a lithium-ion battery cathode material with high theoretical capacity, the application of V2O5 is limited by its unstable structure and low intrinsic conductivity. In this paper, we report a Fe doped V2O5 nanowire with a layered structure of 200–300 nm diameter prepared by electrostatic spinning technique. The 3Fe-V2O5 electrode exhibited a superb capacity of 436.9 mAh g−1 in the first cycle when tested in the voltage range of 2.0–4.0 V at current density of 100 mA g–1, far exceeding its theoretical capacity (294 mAh g−1), and the high capacity of 312 mAh g−1 was still maintained after 50 cycles. The superb performance is mainly attributed to its unique layered nanowire structure and the enhanced electrical conductivity as well as optimized structure brought by Fe-doping. This work made the homogeneous doping and nanosizing of the material easily achieved through electrostatic spinning technology, leading to an increase in the initial capacity of the V2O5 cathode material and the cycling stability compared to the pure V2O5, which is an extremely meaningful exploration.

It is extremely important to develop a high energy density power source with rapid charge-discharge rate to meet people's growing needs. Hence, the development of advanced electrode materials is the top priority. Herein, a simple yet elaborate vacuum-assisted room-temperature phase transfer method is reported to transform MXene nanosheets from water into organic solution. Subsequently, an in-situ growth strategy is employed to deposit ultrathin-walled bismuth sulfide (Bi

The layered vanadium pentoxide (V2O5) application has a good development potential in lithium-ion battery cathode materials. In this paper, vanadium chloride (VCl3), terephthalic acid, and ethanol were served as crude materials to produce precursors of vanadium-based metal organic frameworks by simple solvothermal method. Porous vanadium oxides were synthesized by heat treatment at different temperatures. The results show that the vanadium pentoxide cathode material has a better electrochemical charge and discharge performance and steady cycle by heat treatment of the precursor at 600 °C. The specific capacity of first discharge of the vanadium pentoxide cathode material obtained by heat treatment at 600 °C reached to 324 mAh/g, and when the current density is 50 mA/g, the capacity retention ratio is still 50.6% after 100 cycles. The capacity retention ratio was increased by 16.6% compared to the heat treatment temperature at 400 °C.

Metal ion doping is a common modification method to improve the electrochemical properties of lithium-ion batteries. In this paper, Ga-doped V2O5 lithium-ion battery cathode material was successful...

3D flower-like Li0.36V6O13 has been fabricated via a facile solvothermal method using C2H5OH, V2O5, and LiNO3 as raw materials. The microstructure of the sample was characterized by XRD, FESEM, TEM, and XPS. The lithium storage performance of the sample was investigated by CV, EIS, and charge/discharge test. The results demonstrated that the Li0.36V6O13 sample exhibited greatly improved electrochemical performance as compared with the pristine V6O13. For example, when cycled at 0.1 C for 50 cycles, the capacity retention of the Li0.36V6O13 is 97% much higher than that (57%) of the pristine V6O13. The improvement of the cycle performance of Li0.36V6O13 is attributed to its superior structural reversibility, fewer number of phase transitions during the discharge/charge process, improved electrical conductivity, and enhanced Li+ diffusivity.

With the rapid development of electric vehicles and smart grids, exploring more advanced energy storage technology has become a key issue. Lithium-ion batteries (LIBs) have been considered as one o...

La-doped vanadium pentoxide (V2O5) was prepared by sol–gel method and subsequent heat treatment in air at 400 °C. The influence of La-doping on the crystalline structure, surface morphology, and lithium storage performance of V2O5 were investigated by XRD, SEM, CV, EIS, and discharge–charge tests. The results demonstrated that La doping did not change the phase structure of orthorhombic V2O5, but significantly refined the crystal grain of V2O5; La doping obviously improved the cycling stability and rate capability of V2O5 due to the decreased electrode polarization, smaller electron-transfer resistance, and enhanced lithium diffusivity. For example, the La-doped V2O5 delivered a reversible capacity of 131 mAh/g after 50 cycles at a current density of 200 mA/g, while the pure V2O5 showed a reversible capacity of only 63 mAh/g under the same condition. At the high rate of 500 mA/g, the La-doped V2O5 still displayed a reversible capacity of 106 mAh/g, which is two times higher than that (45 mAh/g) of pure V2O5 sample.