Ultrasmall Co3O4 Nanoparticles Confined in P, N-Doped Carbon Matrices for High-Performance Supercapacitors

Co3O4 nanoparticles with smaller particle size can expose more active sites to react with electrolytes, thereby exhibiting better supercapacitive performance. However, the size of Co3O4 nanoparticles is difficult to be effectively controlled in traditional carbon matrices. Herein, P, N-codoped carbon matrices with ultrahigh surface area and abundant nanocavities are used as a novel host to confine the growth of Co3O4 nanoparticles. The Co3O4/carbon composites with high redox activities of Co3O4 are successfully obtained, in which Co(3)O(4 )nanoparticles are strongly anchored in the carbon matrices, resulting in the enhancement of the composites' capacitive performance (1310 F g(-1) at 0.5 A g(-1)). Meanwhile, the strong anchoring effect of the carbon host on Co(3)O(4 )nanoparticles because of the rich doping elements and the confinement effect of the nanocavities ensure long-term stability (92% capacitance retention after 5000 cycles). Furthermore, the assembled asymmetric supercapacitor using this composite as the cathode material and activated carbon as the anode material delivers a high energy density of 47.18 W h kg(-1) at 375 W kg(-1)

Flexible asymmetric microsupercapacitor with high energy density based on all-graphene electrode system

Flexible asymmetric microsupercapacitor with high energy density based on all-graphene electrode syste

Niobium carbide/reduced graphene oxide hybrid porous aerogel as high capacity and long-life anode material for Li-ion batteries

Niobium carbide/reduced graphene oxide hybrid porous aerogel as high capacity and long-life anode material for Li-ion batterie

Structural Design of Electrocatalyst-Decorated MXenes on Sulfur Spheres for Lithium–Sulfur Batteries

Lithium–sulfur batteries (LSBs) are known to be potential next-generation energy storage devices. Recently, our group reported an LSB cathode made using sulfur spheres that has been spherically templated by MXene nanosheets decorated with CoSe2 nanoparticles, forming a “loose-templating” configuration. It was postulated that the minimal restacking of the outer nanoparticle-decorated MXene layer helps to enable facile ionic transport. However, as the nanosheets do not adhere conformally to the internal sphere’s surface, such a configuration can be controversial, thus requiring a more systematic understanding. In this work, we report and quantify for the first time the independent and dependent variables involved in this morphology, allowing us to identify that having smaller nanoparticles resulted in better Li+ ion transport and enhanced electrochemical performances. The optimized cathode structure exhibited an initial specific capacity of 1274 mAh/g and a 0.06% decay rate per cycle at 0.5 C over 1000 cycles in LSBs

Metal–Organic-Framework-Derived 3D Hierarchical Matrixes for High-Performance Flexible Li–S Batteries

Lithium–sulfur (Li–S) batteries have shown exceptional theoretical energy densities, making them a promising candidate for next-generation energy storage systems. However, their practical application is limited by several challenging issues, such as uncontrollable Li dendrite growth, sluggish electrochemical kinetics, and the shuttling effect of lithium polysulfides (LiPSs). To overcome these issues, we designed and synthesized hierarchical matrixes on carbon cloth (CC) by using metal–organic frameworks (MOFs). ZnO nanosheet arrays were used as anode hosts (CC-ZnO) to enable stable Li plating and stripping. The symmetric cell with CC-ZnO@Li was demonstrated to have enhanced cycling stability, with a voltage hysteresis of ∼25 mV for over 800 h at 1 mA cm–2 and 1 mAh cm–2. To address the cathode challenges, we developed a multifunctional CC-NC-Co cathode host with physical confinement, chemical anchoring, and excellent electrocatalysis. The full cells with CC-ZnO@Li anodes and CC-NC-Co@S cathodes exhibited excellent electrochemical performance, with long cycling life (0.02% and 0.03% capacity decay per cycle when cycling 900 times at 0.5 C and 600 times at 1 C, respectively) and outstanding rate performance (793 mAh g–1 at 4 C). Additionally, the pouch cell based on the flexible CC-ZnO@Li anode and CC-NC-Co@S cathode showed good stability in different bending states. Overall, our study presents an effective strategy for preparing flexible Li and S hosts with hierarchical structures derived from MOF, which can pave the way for high-performance Li–S batteries