Silicon-based (Si-based) materials with high specific capacity are driving the electric vehicle industry and the power storage market. However, poor electrical conductivity and volume expansion during cycling limit its further application. Rational structural designs and specific material selections can be used to create robust volume buffer structures and conductive networks, which consequently contribute to the electrochemical performance of Si materials. Herein, Si particles were encapsulated in the hollow tubular carbon fiber (HT). Further, the porous carbon layer and SnS2 nanosheets were hierarchically assembled on the surface of fibers to create free-standing films with a yolk@multi-shell structure. The unique yolk@multi-shell structure provides sufficient reserved cavities, porous structure, and multiple buffers to significantly resist volume changes. The final electrode is endowed with a multi-dimensional integrated conductive structure by HT and SnS2 nanosheets, which greatly improves the poor conductivity of Si- based electrodes. Finally, the free-standing films can be used directly as anodes, achieving a high specific capacity of 1513.6 mAh g-1 after 100 cycles at 0.1 A g-1 . Additionally, the assembled full cell showed 331.4 mAh g-1 after 100 cycles at 0.2 A g-1 , which contributes significantly to the advancement of power electronics technology. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Silicon based (Si-based) materials are considered to be the most promising anode materials for lithium-ion batteries (LIBs) due to their high specific capacity. However, the issues of poor electrical conductivity and volume expansion during cycling have not been effectively addressed. The optimum remedy is to select specific materials to establish an exceptional conductive and volume buffer structure to assist the Si materials to develop its excellent lithium storage properties. Here, Si particles were encapsulated into porous carbon fibers containing ultrafine Co particles (CP) to obtained Si-x@CP-y film. Among them, the addition of Si particles and the void structure was precisely regulated to achieve a superior electrode with a high specific capacity. Subsequently, the two-dimensional conductive material reduced graphene oxide (rGO) nanosheets were further incorporated to obtain Si-2@CP-2@rGO films with core@multi-shell structure. The final electrode was equipped with one-, two-, and three-dimensional electronic pathways to allow rapid electron transport, and featured with multi-layer buffer structure and reserved pores that could effectively mitigate volume changes. As expected, the free-standing Si-2@CP-2@rGO electrode delivered a high specific capacity of 1221.2 mAh/g after 100 cycles at 0.1 A/g in a half cell, and the assembled full cell showed 249.0 mAh/g after 200 cycles at 0.2 A/g, which fulfilled the lightweight requirement for new energy storage devices.

In view of the growing number of new energy electric vehicles and portable electronic products, the demand for high energy density lithium-ion batteries is crucial. SiO materials have attracted much attention due to their high theoretical specific capacity, but problems of large volume expansion and low conductivity have hindered their practical application in lithium-ion batteries (LIBs). In view of these problems, a SiO@Co9S8 carbon fiber (CF) yolk-shell structured composite electrode was designed in this paper. Among them, the hollow Co9S8 particles have excellent lithium storage capacity and abundant active sites, and the encapsulation effect of SiO nanoparticles (NPs) is better, which can alleviate the problem of excessive volume expansion to a large extent, the SiO@Co9S8 particles are perfectly embedded in CF, which further alleviates the volume expansion of the SiO and Co9S8 materials during cycling, and the one-dimensional CF provides an effective electron transfer channel for electron transfer, which can promote the electrochemical performance of the composite electrode. Thanks to the Co9S8 and CF materials as two protective layers, the stability of the electrode structure is strengthened, and the obtained electrode material has a stable cycle life. As an anode for lithium-ion batteries, SiO@Co9S8 CF exhibits high reversible capacity and good rate performance.

Silicon-based (Si-based) materials offer more possibilities for generating new portable electronic devices due to their high specific capacities. However, their inferior electrical conductivity and volume expansion during cycling seriously limit their development. The optimum solution is to select specific materials to establish an exceptionally conductive and volume buffer structure, which can assist Si materials in developing their excellent lithium storage properties. In this study, Si particles were confined in TiO2 carbon fibers (TiO2 CFs) via electrospinning, after which they were encapsulated with MXene and Co-MoS2 (CMS) nanosheets to fabricate hierarchical ST-2@MXene@CMS films. TiO2 CF, MXene and CMS were employed to establish a coherent conductive network with one-, two- and three-dimensional electronic pathways to permit the unimpeded flow of electrons inside the electrode material. TiO2 CF, MXene and CMS acted precisely as multilayered buffers to ameliorate the volume change of Si particles during cycling. In addition, the CMS nanosheets were involved in lithium storage, contributing to the final electrochemical performance. Ultimately, the ST-2@MXene@CMS films served as free-standing electrodes, avoiding the impact of inactive interfaces on the electrochemical performance and fulfilling the lightweight requirement for new energy storage devices.

CNF-2S has good cycling performance in sodium ion half/full batteries.

Silicon-based(Si-based) materials have attracted considerableattention due to their extremely high specific capacity, while thehuge volume change up to 400% during cycling severely limits theirwidespread use. Silicon-oxygen (SiO x )anode materials, belonging to silicon-based materials, are consideredto be more promising anode materials for practical applications dueto their lower volume expansion without losing the high capacity.However, the existence of the volume expansion and the poor electricalconductivity of SiO x anode materials cannotbe ignored. The encapsulation of SiO x particlesby introducing a conductive carbon layer can greatly alleviate thevolume expansion issue and improve the conductivity of the composites.In addition, to further boost the lithium storage capacity of thecomposites, the SiO x @C@CoO compositeswere obtained by an electrostatic self-assembly of CoO nanosheetsonto the surface of SiO x @C materials.The introduction of CoO nanosheets increased the specific surfacearea of the composites, thereby enlarging the contact area with activeLi(+) and reducing the ion/electron transport radius, whichin turn improved the lithium storage capacity of the composites. Thefinal SiO x @C@CoO composite has an excellentelectrochemical performance, with a reversible capacity of 1120 mAhg(-1) after 100 cycles at 0.2 A g(-1).

Silicon-based (Si-based) materials have aroused extensive attention owing to their ultra-high theoretical specific capacity, while the huge volume expansion and inferior electronic conductivity have impeded their practical application in lithium-ion batteries (LIBs). Rational structural design has been regarded as a fascinating strategy, especially for yolk-shell structures. Herein, Si nanoparticles (Si NPs) were encapsulated in ZIF-67 metal–organic frameworks to obtain Si@ZIF-67 particles, which were wrapped in one-dimensional carbon fibers (CFs) by simple processes of electrospinning, vulcanization and carbonization to obtain a free-standing Si@Co9S8 CF electrode. The yolk-shelled Si@Co9S8 particles could remarkably ameliorate the volume variation of Si materials during the lithiation/de-lithiation cycling and the introduction of CFs endowed an efficient one-dimensional electronic pathway accurately to improve the conductivity of composite materials. In addition, it was not negligible that the as-obtained Si@Co9S8 CF films could be as a self-supporting electrode, which avoided the traditional cumbersome procedure of the electrode preparation. The resulting composite electrodes possess an excellent rate performance and an ultra-stable cycling lifespan. We hope this work can provide some novel insights for the development of the self-supporting Si-based electrode materials.

Rational structure design and regulation are of paramount importance for obtaining electrode materials with desirable electrochemical performance. Here, a novel binder-free electrode with the hollow Co9 S 8 core@multi-shell structure (CS-x@MXene@Bi2O3) derived from metal-organic frameworks (MOFs) precursor is well designed by the electrospinning, sulfuration, carbonization, and hydrothermal processes. In this architecture, the concentration of Co9S8 (CS-x) is optimized for an ideal flexible substrate, which alleviates the dimensional variation for long cycle life. The unique cores and the MXene flakes engineered by Bi2O3 multiple shells can be responsible for the superior characteristics, including a fast electronic pathway, large specific surface area, enhanced electrical conductivity, and improved electrochemical performance. As expected, the obtained CS-2@MXene@Bi2O3 binder-free electrode exhibits a high discharge capacitance of 646.1 F g -1 (1 A g -1 ). Two binder-free electrodes can be assembled into a solid-state super capacitor with desirable energy and power density, and long-term cyclic stability is demonstrated through 50 0 0 cycles. Given these advantages, the CS-2@MXene@Bi2O3 is selected as the electrode in a foldable supercapacitor. More importantly, the specific capacitance is reserved after various deformations. Therefore, it is expected that binder-free electrode materials with the unique core@shell structure design could be applied in wearable and portable energy conversion devices.(c) 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Silicon-based (Si-based) materials have been highlighted for their high specific capacity and abundant reserves. However, the limited electrical conductivity and the large volume expansion are critical barriers to their extensive application. The most targeted remedy is the incorporation of selected conductive materials and the tailored design of electrode structures. Herein, carbon-MXene (C-MXene) and poly(3,4-ethylenedioxythiophene) (PEDOT) were employed to decorate Si cores to obtain Si-x@C-MXene@PEDOT particles. Among them, the content of Si was regulated for an optimal electrochemical performance. More significantly, given that the common single-layer core-shell structure was inherently inadequate in resisting the volume change, the corebishell structure offered a robust buffer layer that consisted of a hard inorganic C-MXene and an organic PEDOT coating with an elastic conductive network, which collaboratively addressed the volume expansion issue. The resulting Si-2@C-MXene@PEDOT also possessed an excellent conductivity-promoting layer consisting of CMXene and PEDOT, which facilitated the rapid transport of electrons, thus significantly boosting the electrochemical performance of the final electrodes. Also, the core-bishell structure assisted in the formation of a thinner solid electrolyte interface (SEI) film, which avoided the massive consumption of Li+ and enhanced the lithium storage capability. This work was expected to open up possibilities for larger-scale applications of Sibased materials.

The design of the core@multi-shell metal sulfide hollow tube is of great importance for various supercapacitor electrodes. Herein, a hollow carbon tube (HCT) core@multi-shell with rich pores is developed for constructing the binder-free flexible electrodes (HCT-x@Co3O4@SnS2). The inner core-shell is derived from the zeolitic imidazole framework (ZIF)-8@ZIF-67 porous carbon tube and is engineered with vertically aligned SnS2 nanosheets. The unique inner core-shell and the outer-shell SnS2 contribute to the excellent characteristics, including abundant pores and channels for the rapid ion transport and storage, high specific surface area, improved electrical conductivity, and additional electroactive sites for the faradaic reaction. Thanks to the synergies between the unique 1D porous hollow structure and the different components, the as-fabricated HCT2@Co3O4@SnS2 electrode exhibits a high specific capacitance of 439 F/g at 1 A/g. Moreover, the assembled flexible supercapacitor also demonstrates a remarkable energy density of 40.22 Wh kg- 1, the corresponding power densities of 750.22 W kg- 1, and long cycle life. In addition, no structural deformation and capacitance loss are observed in the bended devices. The developed approach provides a facile structure design route for the flexible binder-free electrode preparation of flexible energy storage applications.

The large volume expansion effect and unstable solid electrolyte interface films of SiOx-based anode materials have hindered their commercial development. It has been shown that composite doping is a general strategy to solve critical problems. In this study, TiO2-doped core-shell SiOx/ TiO2@C composites were created using the sol-gel method. On the one hand, the uniformly dispersed TiO2 nanoparticles can alleviate the volume expansion of the SiOx active material during the lithiation process. On the other hand, they can react with Li+ to form LixTiO2, thereby increasing the ion diffusion rate in the composite material. The outer carbon shell acts as a protective layer that not only alleviates the volume expansion of the composite, but also improve the electron migration rate of the composite. The prepared SiOx/TiO2@C composite has a reversible capacity of 828.2 mA h g(-1) (0.2 A g(-1) 100 cycles). After 500 cycles, it still maintains a reversible capacity of 500 mA h g(-1) even at a high current density of 2 A g(-1). These findings suggest that SiOx/TiO2@C composites have a bright future in applications.

A flexible Si@CNFs@1T/2H MoS2 film exhibits excellent rate capability and cycling performance with a high initial Coulombic efficiency of 94.5%, which indicates it can be used as a self-supporting electrode for lithium–ion batteries.

Carbon nanofibers (CNFs) have been playing an essential role in addressing the challenges of the flexibility in energy storage devices. However, the unsatisfactory electrochemical performance and poor electrical conductivity are often caused by insufficient physical contact points of CNFs. The design and implementation of unique electrodes are expected to overcome these issues. Here, the N-doped hierarchical porous carbon nanofibers (NCNFs) hollow framework derived from metal-organic frameworks (MOFs) is fabricated, which is decorated with high conductive reduced graphene oxide rGO and single-crystal ZnO nanorod for engineering the binder -free flexible electrodes NCNF@rGO-x@ZnO. The obtained NCNF@rGO-7@ZnO electrode exhibits the desired specific capacitance of 473 F g(-1). An assembled hybrid supercapacitor exhibits the high energy density of 35.16 Wh kg(-1) at the power density of 747.2 W kg(-1), and superior cycling life. Given these advantages, the NCNF@rGO-7@ZnO is selected as the electrode in a flexible and foldable supercapacitor. There is exceptional flexibility and no visible capacitance loss when the supercapacitor bending at different angles. Furthermore, a timer is suc-cessfully driven by two supercapacitor devices connected in series. Hence, a flexible binder-free electrode with excellent electrochemical performance can be obtained by engineering the structure into a hollow interconnected architecture and the rational design of materials.

Hierarchical structural design has been proved to be a new strategy for fabricating high-performance microwave absorbers, so some researchers use low-dimensional components to construct continuous networks for better performance. In this work, the novel hierarchical carbon fibers@ZIF-67@MoS2 film with tunable and efficient electromagnetic wave (EMW) absorption performance was obtained by the electrostatic spinning of ZIF-67 in the interior of carbon fibers and subsequent hydrothermal of MoS2. By the synergistic effects from the ZIF-67 particles increasing the magnetic loss and MoS2 at the outer layer improving the impendence matching, the absorption property of CPZM-1 could be summarized as follow: the optimal reflection loss(RL) was 72.7 dB with a thickness of 2.6 mm at 10.0 GHz and the corresponding effective absorption bandwidth (EAB) of 9.8 GHz covered whole X and Ku band. Moreover, by adjusting the load of ZIF-67, CPZM-5 achieved the maximum EAB of 12.5 GHz.