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In this work, SiO2nanoplates with opened macroporous structure on carbon layer (C-mSiO2) have been obtained by dissolving and subsequent regrowing the outer solid SiO2layer of the aerosol-based C-SiO2double-shell hollow spheres. Subsequently, triple-shell C-mSiO2-C hollow spheres were successfully prepared after coating the C-mSiO2templates by the carbon layer from the carbonization of sucrose. When being applied as the anode material for lithium-ion batteries, the C-mSiO2-C triple-shell hollow spheres deliver a high capacity of 501mA·h·g−1after 100cycles at 500mA·g−1(based on the total mass of silica and the two carbon shells), which is higher than those of C-mSiO2(391mA·h·g−1) spheres with an outer porous SiO2layer, C-SiO2-C (370mA·h·g−1) hollow spheres with a middle solid SiO2layer, and C-SiO2(319.8mA·h·g−1) spheres with an outer solid SiO2layer. In addition, the battery still delivers a high capacity of 403mA·h·g−1at a current density of 1000mA·g−1after 400cycles. The good electrochemical performance can be attributed to the high surface area (246.7m2·g−1) and pore volume (0.441cm3·g−1) of the anode materials, as well as the unique structure of the outer and inner carbon layer which not only enhances electrical conductivity, structural stability, but buffers volume change of the intermediate SiO2layer during repeated charge–discharge processes. Furthermore, the SiO2nanoplates with opened macroporous structure facilitate the electrolyte transport and electrochemical reaction.

In this article, double carbon shell hollow spheres which provide macropores (mC) for ultrasmall Fe3O4nanoparticle (10–20 nm) encapsulation individually were first prepared (Fe3O4@mC). The well-constructed Fe3O4@mC electrode materials offer the feasibility to study the volume change, aggregation, and pulverization process of the active Fe3O4nanoparticles for Li-ion storage in a confined space. Fe3O4@mC exhibits excellent electrochemical performances and delivers a high capacity of 645 mA h g–1at 2 A g–1after 1000 cycles. Even at 10 A g–1or after 1000 cycles at 2 A g–1, the porous carbon structure was well maintained and no obvious aggregation and pulverization of the Fe3O4nanoparticles was observed, although the volume of the active Fe3O4particles was expanded to 40–60 nm compared to that of the original particles (10–20 nm). This can be due to the in situ embedment of one Fe3O4nanoparticle into one macropore individually. The uniform dispersion and confinement of the Fe3O4nanoparticles in the macropores of the carbon shell could effectively accommodate severe volume variations upon cycling and prevent self-aggregation and spreading out from the carbon shell during the expansion process of the nanoscale Fe3O4particles, leading to improved capacity retention. Our work confirms the effectiveness for pulverization control by confining Fe3O4nanoparticles individually into macropores to improve its Li-ion storage properties, providing a novel strategy for the design of new-structured anode materials for Li-ion batteries.

The long-term stability of Li–S batteries is significantly compromised by the shuttle effect and insulating nature of active substance S, constraining their commercialization. Developing efficient catalysts to mitigate the shuttle effect of lithium polysulfides (LiPSs) is still a challenge. Herein, we designed and synthesized a rose-like cobalt–nickel bimetallic oxide catalyst NiCo2O4–OVenriched with oxygen vacancies (OV) and verified the controllable synthesis of different contents of OV. Introducing the OVproved to be an efficient approach for controlling the electronic structure of the electrocatalyst and managing the absorption/desorption processes on the reactant surface, thereby addressing the challenges posed by the LiPS shuttle effect and sluggish transformation kinetics in Li–S batteries. In addition, we investigated the effect of OVin NiCo2O4on the adsorption capacity of LiPSs using adsorption experiments and density functional theory (DFT) simulations. With the increase in the level of OV, the binding energy between the two is enhanced, and the adsorption effect is more obvious. NiCo2O4–OVcontributes to the decomposition of Li2S and diffusion of Li+in Li–S batteries, which promotes the kinetic process of the batteries.