Surface Free Energy‐Induced Assembly to the Synthesis of Grid‐Like Multicavity Carbon Spheres with High Level In‐Cavity Encapsulation for Lithium–Sulfur Cathode

Abstract

Carbon microcapsules with a large interior cavity and porous shell are ideal hosts for guest species, while to maximize in‐cavity volume has always been a challenge. Herein, a surface free energy‐induced assembly approach is proposed for synthesis of multicavity carbon spheres (MCC). When used as a host for lithium–sulfur cathodes, MCC are fully accessible for sulfur—with high level in‐cavity encapsulation ability of grid‐like cavities. The crucial point for this assembly approach is the employment of small sized nanoemulsions with high homogeneity as primary building blocks. Spontaneous aggregation and assembly of substructural units are processing in following hydrothermal synthesis induced by reduction of surface free energy of system. As a result, multicavity structure is formed, where the size and number of cavities can be modulated by changing size of nanoemulsion and concentration of polymer. Confined pyrolysis enables to further enlarge cavity size compared to regular pyrolysis. The carbon–sulfur cathode exhibits excellent cycling stability and rate performance, i.e., high capacity of 943 and 869 mA h g−1 after 200 cycles at current density of 0.5 and 2.0 C. The strategy has paved the way for custom‐ordered synthesis of nanostructured carbon with keen demands in high loading capacity of guest species.

Oxygen Deficiency Driven Conversion of Polysulfide by Electrocatalysis: MoO3‐x Nanobelts for an Improved Lithium‐Sulfur Battery Cathode

“…Up till now, numerous efforts have been devoted to the above limitations. Various porous carbonaceous substrates were proposed to encapsulate sulfur, such as mesoporous carbon, carbon nanotubes, and hollow carbon spheres, which could effectively improve the electric conductivity of cathodes and provide ample space to accommodate the volume fluctuation. Nevertheless, just a weak physical interaction between polar polysulfide molecules and nonpolar carbon surface still made batteries suffer a significant decay during long‐term cycling.…”

Self‐Assembly Synthesis of Mulberry‐Like Fe/N/S‐Doped Highly Porous Carbon Materials: Efficient and Stable Catalysts for Oxygen Reduction Reaction

“…In particular, controlling the size of particles smaller than 200 nm are very essential, because it contributes to the mass transportation by shortening and smoothing the diffusion pathways, resulting in high electrocatalytic activities. [39] Additionally, increasing Fe ions to 2.52% had no effect on the morphology of NCMs ( Figure S1, SEM image of Fe-3/N/S doped NCMs).…”

“…Adding ammonia, the Fe/DA complexes polymerized into Fe/PDA and interacted with F127 micelles to form the Fe/PDA/F127 composite micelles. After further reaction and curing, the assembled Fe/PDA/F127 mulberry‐like structures were formed, likely driven by the reduction of surface free energy of the system, and were finally carbonized into Fe/N/S doped NCMs.…”

3-D Edge-Oriented Electrocatalytic NiCo 2 S 4 Nanoflakes on Vertical Graphene for Li-S Batteries

“…Numerous methods have been investigated to address the polysulfide shuttle effect from different aspects in terms of sulfur host [9], binder [10], separator [11], and electrolyte [12]. Among those electrode engineering strategies, physically blocking the free diffusion of polysulfides by using a mesoporous conductive carbon host [13][14][15] or encapsulating sulfur in a hollow carbon sphere [16][17][18] has been widely reported. Chemically binding and stabilizing LiPSs on a polar host surface is more effective in reducing the shuttle effect.…”