To develop a long cycle life and good rate capability electrode, 3D hierarchical porous α-Fe₂O₃ nanosheets are fabricated on copper foil and directly used as binder-free anode for lithium-ion batteries. This electrode exhibits a high reversible capacity and excellent rate capability. A reversible capacity up to 877.7 mAh g⁻¹ is maintained at 2 C (2.01 A g⁻¹) after 1000 cycles, and even when the current is increased to 20 C (20.1 A g⁻¹), a capacity of 433 mA h g⁻¹ is retained. The unique porous 3D hierarchical nanostructure improves electronic–ionic transport, mitigates the internal mechanical stress induced by the volume variations of the electrode upon cycling, and forms a 3D conductive network during cycling. No addition of any electrochemically inactive conductive agents or polymer binders is required. Therefore, binder-free electrodes further avoid the uneven distribution of conductive carbon on the current collector due to physical mixing and the addition of an insulator (binder), which has benefits leading to outstanding electrochemical performance.

Designed as a high-capacity, high-rate, and long-cycle life anode for sodium-ion batteries, ultrasmall Sn nanoparticles (≈8 nm) homogeneously embedded in spherical carbon network (denoted as 8-Sn@C) is prepared using an aerosol spray pyrolysis method. Instrumental analyses show that 8-Sn@C nanocomposite with 46 wt% Sn and a BET surface area of 150.43 m² g⁻¹ delivers an initial reversible capacity of ≈493.6 mA h g⁻¹ at the current density of 200 mA g⁻¹, a high-rate capacity of 349 mA h g⁻¹ even at 4000 mA g⁻¹, and a stable capacity of ≈415 mA h g⁻¹ after 500 cycles at 1000 mA g⁻¹. The remarkable electrochemical performance of 8-Sn@C is owing to the synergetic effects between the well-dispersed ultrasmall Sn nanoparticles and the conductive carbon network. This unique structure of very-fine Sn nanoparticles embedded in the porous carbon network can effectively suppress the volume fluctuation and particle aggregation of tin during prolonged sodiation/desodiation process, thus solving the major problems of pulverization, loss of electrical contact and low utilization rate facing Sn anode.

Although transition metal oxide electrodes have large lithium storage capacity, they often suffer from low rate capability, poor cycling stability, and unclear additional capacity. In this paper, CoO nanowire clusters (NWCs) composed of ultra-small nanoparticles (≈10 nm) directly grown on copper current collector are fabricated and evaluated as an anode of binder-free lithium-ion batteries, which exhibits an ultra-high capacity and good rate capability. At a rate of 1 C (716 mA g⁻¹), a reversible capacity as high as 1516.2 mA h g⁻¹ is obtained, and even when the current density is increased to 5 C, a capacity of 1330.5 mA h g⁻¹ could still be maintained. Importantly, the origins of the additional capacity are investigated in detail, with the results suggesting that pseudocapacitive charge and the higher-oxidation-state products are jointly responsible for the large additional capacity. In addition, nanoreactors for the CoO nanowires are fabricated by coating the CoO nanowires with amorphous silica shells. This hierarchical core–shell CoO@SiO₂ NWC electrode achieves an improved cycling stability without degrading the high capacity and good rate capability compared to the uncoated CoO NWCs electrode.

We report the synthesis and anode application for sodium-ion batteries (SIBs) of WS₂ nanowires (WS₂ NWs). WS₂ NWs with very thin diameter of ≈25 nm and expanded interlayer spacing of 0.83 nm were prepared by using a facile solvothermal method followed by a heat treatment. The as-prepared WS₂ NWs were evaluated as anode materials of SIBs in two potential windows of 0.01–2.5 V and 0.5–3 V. WS₂ NWs displayed a remarkable capacity (605.3 mA h g⁻¹ at 100 mA g⁻¹) but with irreversible conversion reaction in the potential window of 0.01–2.5 V. In comparison, WS₂ NWs showed a reversible intercalation mechanism in the potential window of 0.5–3 V, in which the nanowire-framework is well maintained. In the latter case, the interlayers of WS₂ are gradually expanded and exfoliated during repeated charge–discharge cycling. This not only provides more active sites and open channels for the intercalation of Na⁺ but also facilitates the electronic and ionic diffusion. Therefore, WS₂ NWs exhibited an ultra-long cycle life with high capacity and rate capability in the potential window of 0.5–3 V. This study shows that WS₂ NWs are promising as the anode materials of room-temperature SIBs.

Layered LiTi_yV_3−0.8yO₈ cathode materials with y=0, 0.04, 0.06, 0.08 were prepared by a sol-gel process following a calcination at 350°C in air for 16 h, and show differences in morphological properties (shape, particle size and specific surface area) and electrochemical properties (first charge profile, reversible capacity and rate capability). The LiTi_yV_3−0.8yO₈ powders were characterized by means of X-ray diffraction (XRD), charge/discharge cycling, cyclic voltammetry (CV), and scanning electron microscopy (SEM). LiTi_yV_3−0.8yO₈ was crystallized to a well layered structure. Its initial specific discharge capacity was higher than that of pristine material. When y=0.04, the sample showed the highest initial discharge capacity of 348.9 mAh·g⁻¹ at a current density of 60 mA·g⁻¹ in the voltage range 1.8–4.0 V, and also higher discharge capacity and better cycle ability.

A series of cathode materials for lithium ion batteries with the formula LiV₃O_8−xCl_x (x=0.00, 0.05, 0.10 and 0.15) were synthesized by a low-temperature solid-state method. The effects of Cl⁻ substitution on the structure, morphology and electrochemical properties of the cathode materials were investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), charge-discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) experiments. The results show that an enhanced cycle performance is on the Cl⁻ doped cathode materials. LiV₃O_7.90Cl_0.10 shows the best electrochemical performances with the discharge capacity remaining 198.6 mAh/g after 100 cycles, which results from a greater reversibility during cycling and decrease of particle-to-particle impedance.