Outer Carbon Shell Research Articles

Watermelon‐Like Structured SiOx–TiO2@C Nanocomposite as a High‐Performance Lithium‐Ion Battery Anode

AbstractA unique watermelon‐like structured SiOx–TiO2@C nanocomposite is synthesized by a scalable sol–gel method combined with carbon coating process. Ultrafine TiO2 nanocrystals are uniformly embedded inside SiOx particles, forming SiOx–TiO2 dual‐phase cores, which are coated with outer carbon shells. The incorporation of TiO2 component can effectively enhance the electronic and lithium ionic conductivities inside the SiOx particles, release the structure stress caused by alloying/dealloying of Si component and maximize the capacity utilization by modifying the Si–O bond feature and decreasing the O/Si ratio (x‐value). The synergetic combination of these advantages enables the synthesized SiOx–TiO2@C nanocomposite to have excellent electrochemical performances, including high specific capacity, excellent rate capability, and stable long‐term cycleability. A stable specific capacity of ≈910 mAh g−1 is achieved after 200 cycles at the current density of 0.1 A g−1 and ≈700 mAh g−1 at 1 A g−1 for over 600 cycles. These results suggest a great promise of the proposed particle architecture, which may have potential applications in the improvement of various energy storage materials.

Superparamagnetic Iron Oxide@Carbon Core–Shell Nanoparticles as Advanced Adsorbent for Efficient Removal of As(V) Ions From Wastewater

In this paper, we have employed the facile one-pot process to synthesize superparamagnetic iron oxide@carbon (Fe3O4@C) core–shell nanoparticles by using ferrocene and acetone as a precursor. The Fe3O4@C nanoparticles were successfully produced by using a solvothermal reaction at 200 °C for 24 h. Effects of synthetic conditions such as amount of ferrocene, solvothermal temperature, and reaction time on the microstructure and formation of Fe3O4@C nanoparticles were optimized. The adsorption activity of arsenic(V) ions on the Fe3O4@C nanoparticles was evaluated and compared with pure Fe3O4 nanoparticles. The adsorption kinetics process of Fe3O4@C nanoparticles was fit well with the Langmuir isotherm model. The adsorption efficiency of the Fe3O4@C core–shell nanoparticles showed better performance of 2.3 times than that of pure Fe3O4 nanoparticles. The adsorption mechanism studies suggest that the enhancement of removal efficiency of Fe3O4@C core–shell nanoparticles was due to improved electrostatic interactions between functional groups presented in outer carbon shell and arsenic(V) ions and therefore increasing adsorption efficiency. With exhibited advantages of low-cost, high-purity, and large-specific surface, the solvothermal-synthesized Fe3O4@C core–shell nanoparticles can be a promising candidate as magnetically separable adsorbent for advanced wastewater treatment applications.

Double-shelled hollow carbon sphere with microporous outer shell towards high performance lithium-sulfur battery

To suppress the dissolution of polysulfides and maintain a high sulfur utilization of lithium-sulfur (Li-S) batteries, double-shelled hollow carbon sphere with a microporous outer carbon shell (m-DSHCS) is designed and fabricated as an efficient sulfur host. Specially, the m-DSHCS with an outer microporous carbon shell and foam-like conductive carbon links is an ideal sulfur host. The foam-like carbon links between the shells and inside the hollow structure can not only provide enough space for sulfur loading and volume expansion, but also facilitate fast electron transfer and Li+ diffusion. Additionally, the outer microporous carbon shell can also serve as an efficient physical barrier to suppress the diffusion of sulfur species derived from inner hollow carbon sphere. When used as cathode material for Li-S batteries, the m-DSHCS/S electrode delivered an outstanding reversible capacities (capacity fading of 0.16% per cycle at 0.2C after 200 cycles and 0.07% per cycle at 1C after 1000 cycles) and superior high-rate capabilities (900 mAh g−1 at 1C and 800 mAh g−1 at 2C) than that of graphene wrapped hollow carbon sphere/sulfur (rGO@HCS/S) electrode (100 cycles at 0.2C with 0.54% capacity fading per cycle, 670 mAh g−1 at 1C and 540 mAh g−1 at 2C).

Cr2O3 ultrasmall nanoparticles filled carbon nanocapsules deriving from Cr(VI) for enhanced lithium storage

Based on the considerations in environmental and economic benefits, Cr2O72− as the major chromium pollutant is employed for applications in energy storage. A novel Cr2O3 ultrasmall nanoparticles (NPs) (<5 nm) filled carbon nanocapsule configuration is achieved through a surfactant-free solvothermal route with renewable furfural as the carbon source. The confinement effect that Cr2O3 NPs are restrained in the outer robust carbon shell and the plenty space among Cr2O3 NPs result in substantially enhanced Li-storage performances, such as stable capacity of 568 mAh g−1 at 100 mA g−1 after more than 200 cycles and high capacity retention at large current density.

Core-Shell Structured SiOx-TiO2@C Nanocomposites As High-Rate and Long-Cycle Anode for Lithium Ion Batteries

Silicon suboxide (SiOx, 0˂x˂2) is one of the promising anode materials for lithium-ion batteries (LIBs) due to its high specific capacity, low operating voltage (˂0.4 V) and rich abundance [1]. SiOx produces inert components (lithium oxide and lithium silicate) and nano-Si particles during initial lithiation/delithiation process. The former can act as buffer matrix to significantly reduce the volume change of nano-sized Si. Therefore, compared to pure Si, SiOx electrode shows relatively good cycling stability and thus appears promising for high energy density Li-ion batteries. Nevertheless, the poor intrinsic electronic and ionic conductivity of SiOx often leads to a low specific capacity and inferior rate capability [2]. In addition, the SiOx electrode cannot withstand long-period cycling due to the inevitable volume variation of SiOx. In this work, we prepared core-shell SiOx-TiO2/C nanoparticles with unique watermelon-like structured by a simple sol-gel combined with a following carbon coating process. Ultrafine TiO2 nanocrystals are homogeneously distributed inside SiOx particles, forming SiOx-TiO2 dual-phase cores, which are coated with outer carbon shells. The incorporation of TiO2 component can effectively enhance the electronic and lithium ionic conductivities, release the structure stress caused by alloying/dealloying of Si component and maximize the capacity utilization by decreasing the O/Si ratio (x value). The synergetic combination of these advantages enables the synthesized SiOx-TiO2@C nanocomposite to have outstanding electrochemical performances, including high specific capacity, excellent rate capability and stable long term cycleability. A stable specific capacity of ~910 mAh g-1 is achieved after 200 cycles at the current density of 0.1 A g-1 . These results suggest the synthesized SiOx-TiO2/C composite is a promising high performance anode material for lithium ion batteries.

Mesoporous Hollow Sb/ZnS@C Core–Shell Heterostructures as Anodes for High‐Performance Sodium‐Ion Batteries

Combining the advantage of metal, metal sulfide, and carbon, mesoporous hollow core-shell Sb/ZnS@C hybrid heterostructures composed of Sb/ZnS inner core and carbon outer shell are rationally designed based on a robust template of ZnS nanosphere, as anodes for high-performance sodium-ion batteries (SIBs). A partial cation exchange reaction based on the solubility difference between Sb2 S3 and ZnS can transform mesoporous ZnS to Sb2 S3 /ZnS heterostructure. To get a stable structure, a thin contiguous resorcinol-formaldehyde (RF) layer is introduced on the surface of Sb2 S3 /ZnS heterostructure. The effectively protective carbon layer from RF can be designed as the reducing agent to convert Sb2 S3 to metallic Sb to obtain core-shell Sb/ZnS@C hybrid heterostructures. Simultaneously, the carbon outer shell is beneficial to the charge transfer kinetics, and can maintain the structure stability during the repeated sodiation/desodiation process. Owing to its unique stable architecture and synergistic effects between the components, the core-shell porous Sb/ZnS@C hybrid heterostructure SIB anode shows a high reversible capacity, good rate capability, and excellent cycling stability by turning the optimized voltage range. This novel strategy to prepare carbon-layer-protected metal/metal sulfide core-shell heterostructure can be further extended to design other novel nanostructured systems for high-performance energy storage devices.

Carbon-shell-constrained silicon cluster derived from Al-Si alloy as long-cycling life lithium ion batteries anode

Although silicon is the most promising anode material for Li-ion batteries, large volume expansion during lithiation and delithiation is the main obstacle limiting the commercial application of silicon anodes. There are two ways to alleviate volume expansion and prevent further pulverization of a Si anode: fabrication of a rational nanostructure possessing void spaces and uniform distribution of the conducting sites, without a good balance effect in mitigating the limiting factors and enhancing battery performance. In this paper, we propose a novel nanostructure — a carbon-shell-constrained Si cluster (Si/C shell) with both adequate void space and good distribution of electrical contact sites to guarantee homogeneous lithiation in the initial cycle. Benefiting from the ability to maintain electrical conductivity of the outer carbon shell, even after cluster fragmentation, the Si/C shell synthesized from low-cost commercial Al-Si alloy spheres can deliver 0.03% capacity loss from 100th to 1000th cycles at a current density of 1 A g−1. The Si/C shell sample with the dual functional structure mentioned above can also maintain its own nanostructure during cycling and deliver excellent rate performance. It is a concise and scalable strategy which can simplify the preparation of other alloy anode materials for Li-ion batteries.

Functional Differentiation of Three Pores for Effective Sulfur Confinement in Li-S Battery.

Shuttle effect of the dissolved intermediates is regarded as the primary cause that leads to fast capacity degradation of Li-S battery. Herein, a microporous carbon-coated sulfur composite with novel rambutan shape (R-S@MPC) is synthesized from microporous carbon-coated rambutan-like zinc sulfide (R-ZnS@MPC), via an in situ oxidation process. The R-ZnS is employed as both template and sulfur precursor. The carbon frame of R-S@MPC composite possesses three kinds of pores that are distinctly separated from each other in space and are endowed with the exclusive functions. The central macropore serves as buffer pool to accommodate the dissolved lithium polysulfides (LPSs) and volumetric variation during cycling. The marginal straight-through mesoporous, connected with the central macropore, takes the responsibility of sulfur storage. The micropores, evenly distributed in the outer carbon shell of the as-synthesized R-S@MPC, enable the blockage of LPSs. These pores are expected to perform their respective single function, and collaborate synergistically to suppress the sulfur loss. Therefore, it delivers an outstanding cycling stability, decay rate of 0.013% cycle-1 after 500 cycles at 1 C, when the sulfur loading is kept at 4 mg cm-2 .

Green Fabrication of Silkworm Cocoon-like Silicon-Based Composite for High-Performance Li-Ion Batteries.

Designing yolk-shell nanostructures is an effective way of addressing the huge volume expansion issue for large-capacity anode and cathode materials in Li-ion batteries (LIBs). Previous studies mainly focused on adopting a SiO2 template through HF etching to create yolk-shell nanostructures. However, HF etching is highly corrosive and may result in a significant reduction of Si content in the composite. Herein, a silkworm cocoon-like silicon-based composite is prepared through a green approach in which Al2O3 was selected as a sacrificial template. The void space between the outer nitrogen-doped carbon (NC) shell formed by chemical vapor deposition using a pyridine precursor and the inside porous silicon nanorods (p-Si NRs) synthesized by magnesiothermic reduction of ordered mesoporous silica nanorods can be generated by etching Al2O3 with diluted HCl. The obtained p-Si NRs@void@NC composite is utilized as an anode material for LIBs, which exhibits a large initial discharge capacity of 3161 mAh g-1 at 0.5 A g-1, excellent cycling behavior up to 300 cycles, and super rate performance. Furthermore, a deep understanding of the mechanism for the yolk-shell nanostructure during the Li-alloying process is revealed by in situ transmission electron microscopy and finite element simulation.

Promotional role of Li 4 Ti 5 O 12 as polysulfide adsorbent and fast Li + conductor on electrochemical performances of sulfur cathode

Abstract Lithium-sulfur (Li-S) batteries attract much attention due to its high specific capacity and energy density compared to lithium-ion batteries (LiBs). Herein, a novel composite named as (void/nano-Li 4 Ti 5 O 12 pieces)@C [(v/n-L)@C] was designed and prepared as a sulfur host. Spinel Li 4 Ti 5 O 12 here as a multifunctional additive played as polysulfide adsorbent agent and fast Li + conductor, and carbon shell was designed as electronic conductor, as well as volume barrier to limit the volume expansion caused by sulfur. As-prepared (S/nano-Li 4 Ti 5 O 12 pieces)@C [(S/n-L)@C] are core-shell spheres, which are about 200 nm in size. Nano-Li 4 Ti 5 O 12 and sulfur were coated by the outer carbon shell with a thickness of about 20 nm. The experimental results show that electrochemical performances of (S/n-L)@C cathode were enhanced effectively compared to S@C cathode. At 0.5C and 1C, the discharge capacity of (S/n-L)@C was 33.5% and 40.1% higher than that of S@C at 500 th cycle. Even at 2C, its capacity reached 600.9 mAh g −1 at 1000 th cycle. Li + conductivity of (S/n-L)@C was one order of magnitude higher than that of S@C, which was reach to 2.55 × 10 −8 S cm −1 . The experiment results indicate Li 4 Ti 5 O 12 plays a promotional role on electrochemical performances of sulfur cathode, especially for stable cycling performance and high rate performance.

In-depth nanocrystallization enhanced Li-ions batteries performance with nitrogen-doped carbon coated Fe3O4 yolk−shell nanocapsules

Abstract In this paper nitrogen-doped carbon-encapsulation Fe3O4 yolk−shell magnetic nanocapsules (Fe3O4@C-N nanocapsules) have been successfully constructed though a facile hydrothermal method and subsequent annealing process. Fe3O4 nanoparticles are completely enclosed in nitrogen-doped carbon shells with void space between the nanoparticle and the shell. The yolk−shell structure allows Fe3O4 nanoparticles to expand freely without breaking the outer carbon shell during the lithiation/delithiation processes. The volume expansion of Fe3O4 results in the in-depth nanocrystallization. Fortunately, the new generated small nanoparticles can increase the capability with the cycle increase due to the unique confinement effect and excellent electronic conductivity of the nitrogen-doped carbon shells. Hence, after 150 cycles, the discharge capacity of Fe3O4@C-N-700 nanocapsules still remained 832 mA h g−1 at 500 mA g−1, which corresponds to 116.7% of the lowest capacity (713 mA h g−1) at the 16th cycle. We believe that the yolk−shell structure is conducive to enhance the capacity of easy pulverization metal oxidation during the charge/discharge processes.

Synthesis of core-shell-like ZnS/C nanocomposite as improved anode material for lithium ion batteries

ZnS/C nanoparticles with core/shell structure are prepared by a simple solvothermal process followed by an annealing process. The core consists of a quite amount of ultrasmall ZnS nanocrystals (∼10nm) dispersing in in situ formed carbon matrix, which is covered by an outer carbon shell with ∼4nm thickness. The nano-sized ZnS crystals effectively shorten the lithium ion diffusion paths, while the uniform carbon shell, together with the inner amorphous carbon matrix not only provide fast electron conduction, but also act as a buffer matrix to accommodate volume change occurring on electrochemical cycling. Such hierarchical-type microstructure is beneficial concerning electrochemical performance of the proposed composite. When evaluated as an anode material for rechargeable lithium ion batteries, the ZnS/C nanocomposite shows a high specific capacity of 741mAhg−1 at a current density of 0.1Ag−1 after 300 cycles. Even at 5Ag−1, a high reversible capacity of 538mAhg−1 can be still achieved. The lithium diffusion coefficient of ZnS/C electrode is estimated as 6.1×10−11cm2s−1, contributing to the excellent rate performance of the material.

Core–shell reduced graphene oxide/MnOx@carbon hollow nanospheres for high performance supercapacitor electrodes

We demonstrate a novel and efficient approach to fabricate reduced graphene oxide (RGO)/MnOx@carbon hollow nanospheres (HCNs) nanohybrids for high performance supercapacitor application. Mn2+ ions can bind with negatively charged O atoms on graphene oxide (GO) via electrostatic forces to generate RGO/MnOx (x⩽2) under hydrothermal condition. This process was utilized to grow MnOx layers on the surfaces of RGO, and the RGO/MnOx was encapsulated within the outer carbon shell to obtain RGO/MnOx@HCNs. RGO/MnOx@HCNs have a regular hollow structure with uniform outer shells (∼10nm) and inner spherical pores (∼150nm), high surface areas (493–668m2g−1), and high contents of MnO2 (12.2–19.6wt%). As-designed ternary core–shell 3D nanoarchitecture prevents the leaching of loaded manganese oxides and avoids the aggregation of RGO within the carbon shell, which effectively guarantees the electrochemical activity of each electroactive components. Consequently, a typical RGO/MnOx@HCNs as a supercapacitor electrode exhibits a high specific capacitance (355 and 270Fg−1 in a three-electrode and two-electrode system at 1.0Ag−1, respectively) in 6M KOH electrolyte. Besides, the electrode shows a high rate charge–discharge capability (20.0Ag−1), and good electrochemical stability (88% capacitance retention after 5000 cycles at 0.5Ag−1). The results suggest that the core–shell RGO/MnOx@HCNs nanostructures provide promising prospects for electrochemical energy storage applications.

Polydopamine derived porous N-doped carbon nanofibers for lithium ion storage

Porous N-doped carbon nanofibers derived from polydopamine are fabricated by a facile carbonized technique and a subsequent template-removing process. Superior to the other porous carbon nanomaterials that voids are directly exposed in the electrolyte, the nanopores in our designed nanofibers are confined by the inner carbon walls and outer carbon shells. The prepared porous N-doped carbon nanofibers electrode shows high reversible capacities of 1324mAhg−1 after 150 cycles at 0.2Ag−1 and 780mAhg−1 after 500 cycles at 1Ag−1.

Sulfur-Infiltrated Hierarchical Porous Carbon (HPC) Cathodes for Lithium-Sulfur Batteries

Lithium sulfur (Li-S) batteries have been considered as promising candidates for next-generation battery applications because of its high theoretical capacity (1675 mAh/g is 5 times higher than those of traditional cathode materials based on transition metal oxides or phosphates), abundance, safety, low cost, and eco-friendliness. However, the practical implementation of Li-S batteries is greatly hindered by the high resistance of sulfur (5 x 10-30 S cm-1 at 25 oC) and dissolution of soluble long-chain lithium polysulfides (Li2Sn, 4≤n≤8) in the polar organic electrolytes, and volume expansion of sulfur during discharge process, resulting in an insufficient cycle life. To this end, a number of studies have focused mainly on the development of carbon-sulfur composite with the intention to improve the cycle stability. Many types of mesoporous carbon materials have been studied as the electrically conducting host materials for improving the electrical conductivity of sulfur and preventing dissolution of soluble long-chain lithium polysulfides, which are intermediates formed as reaction in both discharge and charge processes in the electrolytes. Those approaches improve the electrical conductivity of sulfur, but are associated with inherent limitation of the dissolution of polysulfides due to the limitation of physical adsorption of the polysulfides by mesopores, which tends to limit the electrochemical performance of carbon-sulfur composite cathode materials. Recently, to overcome these problems, microporous carbon materials have been designed. Although the characterization of sulfur confined in micropores is not completely determined, the micropores have indeed turned out to be efficacious in mitigation of the soluble lithium polysulfides via various mechanisms: (1) strong adsorption of soluble polysulfides, (2) construction of solvent-free environment, and (3) formation of insoluble small S2-4 molecules. Because of these attributes, the microporous carbon-sulfur composites show outstanding cycling performance and rate capability. Additionally, Manthiram et al. reported a novel Li-S cell configuration having carbon interlayers with micropores between the separator and the regular sulfur electrodes. This interlayer works as polysulfide stockroom to maintain the cycle stability. Based on these micropore approaches, we combined sulfur encapsulation and micropores into a single electrode component by developing a hierarchical porous carbon (HPC) structure. In the HPC structure prepared by spray pyrolysis process, the inner meso- and macro- pores are surrounded by outer carbon shell with micropores. Hence, stable cycling was achieved by the outer micropores that shut dissolution of lithium polysulfides down, while most of active sulfur was loaded in the larger inner pores.

Fabrication of voids-involved SnO2@C nanofibers electrodes with highly reversible Sn/SnO2 conversion and much enhanced coulombic efficiency for lithium-ion batteries

Despite their potential application in lithium-ion battery electrodes, one apparent disadvantage for SnO2-based materials is that the electrodes suffer low coulombic efficiency especially for the initial cycle, which originates from the irreversible conversion of SnO2 to Sn, the formation of solid electrolyte interphase and the other possible side reactions. Here we design a novel nanofiber structure in which SnO2 nanoparticles are well separated and confined by inner porous carbon framework and then hooped by outer carbon shell. The resultant SnO2/[email protected] nanofibers electrode displays not only a high reversible capacity of 986 mAh g−1 at 200 mA g−1 after 200 cycles, but also a high initial coulombic efficiency of 73.5%. It has been shown that such a rational design can efficiently reduce the side reactions and promote the reversible conversion of Sn to SnO2 for both half and full cells.

Graphitic cage transformation by electron-beam-induced catalysis with alkali-halide nanocrystals

We found that alkali-halide nanocrystals, such as KCl and NaCl, have strong catalytic capability to form graphitic carbon cages from amorphous carbon shells under electron beam irradiation. In addition to the electron beam irradiation strongly inducing the decomposition of alkali-halide nanocrystals, graphene fragments were formed and linked together to form the final product of thin graphitic carbon cages after the evaporation of alkali-halide nanocrystals. The required electron dose was approximately 1 to 20 C/cm2 at 120 keV at room temperature, which was about two orders of magnitude smaller than that required for conventional beam-induced graphitization. The “knock-on” effect of primary electrons strongly induced the decomposition of the alkali-halide crystal inside the amorphous carbon shell. However, the strong ionic cohesion quickly reformed the crystal into thin layers inside the amorphous shell. The bond excitation induced by the electron beam irradiation seemed to enhance strongly the graphitization at the interface between the outer amorphous carbon shell and the inner alkali-halide crystal.

Co@Co3 O4 @PPD Core@bishell Nanoparticle-Based Composite as an Efficient Electrocatalyst for Oxygen Reduction Reaction.

Durable electrocatalysts with high catalytic activity toward oxygen reduction reaction (ORR) are crucial to high-performance primary zinc-air batteries (ZnABs) and direct methanol fuel cells (DMFCs). An efficient composite electrocatalyst, Co@Co3 O4 core@shell nanoparticles (NPs) embedded in pyrolyzed polydopamine (PPD) is reported, i.e., in Co@Co3 O4 @PPD core@bishell structure, obtained via a three-step sequential process involving hydrothermal synthesis, high temperature calcination under nitrogen atmosphere, and gentle heating in air. With Co@Co3 O4 NPs encapsulated by ultrathin highly graphitized N-doped carbon, the catalyst exhibits excellent stability in aqueous alkaline solution over extended period and good tolerance to methanol crossover effect. The integration of N-doped graphitic carbon outer shell and ultrathin nanocrystalline Co3 O4 inner shell enable high ORR activity of the core@bishell NPs, as evidenced by ZnABs using catalyst of Co@Co3 O4 @PPD in air-cathode which delivers a stable voltage profile over 40 h at a discharge current density of as high as 20 mA cm(-2) .

A Green and Facile Way to Prepare Granadilla‐Like Silicon‐Based Anode Materials for Li‐Ion Batteries

A yolk‐shell‐structured carbon@void@silicon (CVS) anode material in which a void space is created between the inside silicon nanoparticle and the outer carbon shell is considered as a promising candidate for Li‐ion cells. Untill now, all the previous yolk‐shell composites were fabricated through a templating method, wherein the SiO2 layer acts as a sacrificial layer and creates a void by a selective etching method using toxic hydrofluoric acid. However, this method is complex and toxic. Here, a green and facile synthesis of granadilla‐like outer carbon coating encapsulated silicon/carbon microspheres which are composed of interconnected carbon framework supported CVS nanobeads is reported. The silicon granadillas are prepared via a modified templating method in which calcium carbonate was selected as a sacrificial layer and acetylene as a carbon precursor. Therefore, the void space inside and among these CVS nanobeads can be formed by removing CaCO3 with diluted hydrochloric acid. As prepared, silicon granadillas having 30% silicon content deliver a reversible capacity of around 1100 mAh g−1 at a current density of 250 mA g−1 after 200 cycles. Besides, this composite exhibits an excellent rate performance of about 830 and 700 mAh g−1 at the current densities of 1000 and 2000 mA g−1, respectively.

Hollow-in-hollow carbon spheres with hollow foam-like cores for lithium–sulfur batteries

Lithium-sulfur batteries have attracted increasing attention because of their high theoretical capacity. Using sulfur/carbon composites as the cathode materials has been demonstrated as an effective strategy to optimize sulfur utilization and enhance cycle stability as well. In this work, hollow-in-hollow carbon spheres with hollow foam-like cores (HCSF@C) are prepared to improve both capability and cycling stability of lithium–sulfur batteries. With high surface area and large pore volumes, the loading of sulfur in HCSF@C reaches up to 70 wt.%. In the resulting S/HCSF@C composites, the outer carbon shell serves as an effective protection layer to trap the soluble polysulfide intermediates derived from the inner component. Consequently, the S/HCSF@C cathode retains a high capacity of 780 mAh/g after 300 cycles at a high charge/discharge rate of 1 A/g.