Selenium-Doped Amorphous Black Phosphorus@TiO2/C Heterostructures for High-Performance Li/Na/K Ion Batteries

Metal-Organic Framework-Based Materials for Advanced Sodium Storage: Development and Anticipation

As a pioneering battery technology, even though sodium-ion batteries (SIBs) are safe, non-flammable, and capable of exhibiting better temperature endurance performance than lithium-ion batteries (LIBs), because of lower energy density and larger ionic size, they are not amicable for large-scale applications. Generally, the electrochemical storage performance of a secondary battery can be improved by monitoring the composition and morphology of electrode materials. Because more is the intricacy of a nanostructured composite electrode material, more electrochemical storage applications would be expected. Despite the conventional methods suitable for practical production, the synthesis of metal-organic frameworks (MOFs) would offer enormous opportunities for next-generation battery applications by delicately systematizing the structure and composition at the molecular level to store sodium ions with larger sizes compared with lithium ions. Here, the review comprehensively discusses the progress of nanostructured MOFs and their derivatives applied as negative and positive electrode materials for effective sodium storage in SIBs. The commercialization goal has prompted the development of MOFs and their derivatives as electrode materials, before which the synthesis and mechanism for MOF-based SIB electrodes with improved sodium storage performance are systematically discussed. Finally, the existing challenges, possible perspectives, and future opportunities will be anticipated.

3D ordered amorphous and porous TiO2 framework anode with low insertion barrier and fast kinetics for K-ion hybrid capacitors

TiO₂ is considered as a low cost, long-term stable, and safe anode for high power K-ion hybrid capacitors (KICs) due to its abundant reserve, small volume expansion rate, and sloping voltage plateau that avoids K-ion plating at high voltage polarization. However, the enhancement of its low capacity and sluggish kinetics caused by poor electroconductivity and high insertion barrier is still challenging to further develop high-performance KICs. Herein, the reduced graphene oxide (rGO) is embedded in the walls of 3D ordered macro-/mesoporous TiO₂ (termed as TiO₂@rGO framework) to create intimate TiO₂/rGO interfaces, ensuring the effectively electron transportation during potassiation/depotassiation of TiO₂ while maintaining rapid ions/electrolyte diffusion. Furthermore, the controlled amorphous TiO₂ framework can further lower the lattice insertion energies, contributing to a fast accommodation of K-ion. As expected, the amorphous TiO₂@rGO framework (TiO₂@rGO-1) exhibits a superior rate capability (148.8 mAh g^-1 at 5 A g^-1) and cycling stability (171.2 mAh g^-1 at 1 A g^-1 after 800 cycles). The assembled KICs can reach a high energy/power density of 125.2 Wh kg^-1/4267.4 W kg^-1 as well as a long-term lifespan. This tactic provides a reliable and general way to design a TiO₂-based anode with fast kinetics toward high-performance KICs.