Monodisperse V₂O₅ microspheres with a porous structure were synthesized by a very simple hydrolysis method and subsequent reduction/oxidation treatment at high temperatures. The porous V₂O₅ used as a cathode material for lithium-ion batteries (LIBs) shows a stable and highly reversible capacity. It also shows excellent low-temperature behavior with a reversible capacity of 102 mA h g⁻¹ at −20 °C. The excellent performance can be attributed to the porous structure of the V₂O₅ spheres, which are more electrochemically active due to a large interfacial contact area with the electrolyte. We believe the strategy of creating porosity may be extended to other electrode materials to improve the performance of lithium ion batteries.

We prepare a totally nonflammable phosphate-based electrolyte composed of 5 mol L⁻¹ (M) Li bis(fluorosulfonyl) imide (LiFSI) in a trimethyl phosphate (TMP) solvent. The concentrated 5 M LiFSI/TMP electrolyte shows good compatibility with graphite and no Al corrosion. More attractively, such a concentrated electrolyte can effectively suppress the growth of Li dendrites in Li metal batteries because of a stable LiF-rich SEI layer. Therefore, this highly concentrated electrolyte is promising for safe Li batteries.

K-ion batteries, as an emerging battery system, have attracted tremendous attention in the research community. Herein, we report a K-ion full-cell based on a nano-sized K_1.92Fe[Fe(CN)₆]_0.94·0.5H₂O cathode, dipotassium terephthalate (K₂TP)@carbon nanotube (CNT) anode and an optimized electrolyte. K_1.92Fe[Fe(CN)₆]_0.94·0.5H₂O delivers a high capacity of 133 mA h g⁻¹ with 92.8% capacity retention after 200 cycles and high coulombic efficiency of 98.5%. The side reactions of K metal with the electrolyte are suppressed in KClO₄/propylene carbonate (PC). The K₂TP nanosheets grown in situ on the CNT show a high reversible capacity of about 250 mA h g⁻¹ and an ultra-high rate capability. The full-cells based on them are well cycled in a DME-based electrolyte and show a great promise for large-scale energy storage.

Three-dimensional (3D) porous vanadium pentoxide (V₂O₅) thin films were synthesized by electrostatic spray deposition followed by annealing at 350 °C in air. The interconnected pore networks facilitate the kinetics of lithium-ion diffusion and help the porous V₂O₅ with stable capacity, high energy efficiency and excellent rate capability as a cathode material for lithium batteries.