The applications such as electric vehicles require a high energy density in lithium-ion batteries. LiNi_0.9Co_0.1O₂ has attracted much attention, which has a potential to be next-generation cathode material due to its high specific capacity and reasonable cost. However, some related issues such as Li/Ni mixing, microcracks and surface side reactions caused by H2–H3 phase transformation result in a poor cycling stability for LiNi_0.9Co_0.1O₂. In this paper, the microstructures of LiNi_0.9Co_0.1O₂ by W⁶⁺ doping were regulated by an effective method to adjust the surface energy of the primary particles and transform the disordered and irregular-shape primary particles into the well-ordered radially-aligned elongated shape particles. This microstructure feature can suppress the stress accumulation and the formation of micro-cracks in LiNi_0.9Co_0.1O₂, and provide abundant diffusion channels for Li⁺, thus improving the cycling stability and rate performance of LiNi_0.9Co_0.1O₂ cathode materials. The discharge capacities of 1% (in mole fraction) W-doped LiNi_0.9Co_0.1O₂ are 231.2 mA·h/g at 0.1 C and 213.3 mA·h/g at 0.5 C, respectively, with a high capacity retention of 93% after 150 cycles. This microstructure regulation strategy provides an effective approach for improving the cycling stability of LiNi_0.9Co_0.1O₂ Ni-rich cathode materials.

It is important for the further improvement of lithium-ion battery energy densities to develop high-specific-capacity cathode materials. Li₃V₂O₅ has attracted much attention due to its high specific capacity, even exceeding 240 mA·h/g. However, its low electrochemical cycling stability induced by the low Li⁺ transport dynamics and irreversible phase transition restricts the application of Li₃V₂O₅ cathode materials in lithium-ion batteries. In this paper, co-doped Li₃V₂O₅ nanorod cathode materials were prepared. The one-dimensional structure can relieve the accumulation of strain during charging and discharging process. Also, Co³⁺ doping can stabilize the structure of Li₃V₂O₅ by forming the more intense Co—O bonds. Furthermore, Co³⁺ doping expands the cell volume and ratio of V⁴⁺ in Li₃V₂O₅. These collectively result in the improved Li⁺ diffusion coefficient and cycling stability of Li₃V₂O₅. The 1% Co-doped Li₃V₂O₅ (i.e., 1%Co–LVO sample) has a specific discharge capacity of 256.43 mA·h/g at a current density of 50 mA/g and a capacity retention rate of 77.3% after 100 cycles, which is 28% greater than that of the pristine Li₃V₂O₅. 1%Co–LVO sample shows a superior capacity fading (i.e., 0.23%/cycle). This paper can provide an effective method for the preparation and performance regulation of high-energy-density lithium-ion cathode material (i.e., Li₃V₂O₅).

WO₃ electrochromic devices (ECDs) with the short response time and high optical contrast show great application potentials in car rearview mirrors and smart windows. With the rapid development of wearable electronics, the fabrication of flexible WO₃ films for bendable ECDs has attracted much attention. However, the fabrication of flexible crystalline WO₃ films generally requires a sophisticated vacuum vapor deposition technique, including magnetron sputtering and electron-beam deposition due to the high crystallization temperature of WO₃ and the limited endurable temperature of polymer substrates. The dense WO₃ layers on polymer substrates affect the facile access of electrolyte and fast intercalation/deintercalation of electrolyte ions. In this paper, well-crystallized WO₃·H₂O microplate powders were pre-synthesized by a chemical reflux method. Monoethanolamine was utilized to intensively dissociate WO₃·H₂O microplates into a well-dispersed colloidal solution. The flexible nanocrystalline WO_x/polyethylene terephthalate films were fabricated via spin coating deposition and assembled into the flexible ECDs. The accumulated charge repulsion provided by the intense interfacial interaction between amine group and WO₃·H₂O microplates results in their fast dissociation. The fabricated flexible crystalline WO_x electrochromic devices have short coloring and bleaching time of 5.9 s and 5.4 s, respectively, and a coloring efficiency of 146.7 cm²/C, and still exhibit the superior performance after 200 bending cycles.