In Situ Pyrolysis Concerted Formation of Si/C Hybrids during Molten Salt Electrolysis of SiO2@Polydopamine

Modified SiO2@cinnamaldehyde/nanocellulose coating film for loquat preservation

Although cinnamaldehyde (CA) is an excellent antimicrobial agent, its application in the food industry was limited by its volatility and lack of antimicrobial persistence. Herein, aminated hollow mesoporous silica (NH2-HMSN) was prepared by selective etching and amino-modified. Subsequently, long-acting antibacterials with regulated release (NH2-HMSN@CA) were obtained by using NH2-HMSN as cinnamaldehyde carrier. NH2-HMSN@CA can effectively regulate the release of CA, and has 100 % inhibition effect on the growth of E. coli, S. aureus and C. acutatum. In addition, nanocellulose/NH2-HMSN@CA (CHA) coating film was prepared for postharvest preservation of loquat. The coating film effectively improved the storage quality and shelf life of loquat, and delayed the postharvest decay of loquat. The prepared coating film active packaging for long-term preservation is expected to provide a scheme for promoting sustainable preservation of postharvest loquat.

MXene-NH2/chitosan hemostatic sponges for rapid wound healing

Effective control of wound bleeding and sustained promotion of wound healing remain a major challenge for hemostatic materials. In this study, the hemostatic sponge with controllable antibacterial and adjustable continuous promotion of wound healing (CMNCu) was prepared by chitosan, aminated MXene and copper ion. Interestingly, the internal topological point-line-surface interaction endowed the CMN-Cu sponge longitudinal staggered tubular porous microstructure, combined with the lipophilic properties obtained by modified MXene, which greatly improved its flexibility, wet elasticity and blood enrichment capacity. In addition, the sponge achieved controlled release of active ingredients, which made it present highly effective antibacterial activity and long-lasting ability to promote wound healing. In vitro and in vivo experiments confirmed that CMN-Cu sponge presented high-efficient hemostatic performance. Last but not least, a series of cell experiments showed that the CMN-Cu sponge had excellent safety as a hemostatic material.

Activating biomass carbon with metallurgical slag by pyrolysis in molten salt for high-performance supercapacitors

Pyrolysis of sustainable biomass to advanced carbon materials for energy storage is key-enabling in energy and environmental sustainability. However, obtaining carbon materials with well-defined microstructure and composition for high-performance energy storage is extremely challenging. Herein, efficient activation of biomass carbon is realized by introducing extra metallurgical slag during pyrolysis of coconut shell in Na₂CO₃-K₂CO₃ molten salt. The molten salt guides the formation of carbon with a hierarchical honeycomb-like nanostructure, while the metallurgical slag facilitates enhanced doping of the heteroatom species, conjointly contributing to the increase of the specific surface area of carbon materials from 424 m² g^-1 to 1451 m² g^-1 and the extension of the single N dopant to multiple dopants of N, P, Zn and Co. Such adequate tuning of the microstructure and composition in the pyrolysis product increases the capacitance for supercapacitors from 30 F g^-1 to 135 F g^-1 at 0.5 A g^-1. The results can provide new insights for the controllable upgradation of both biomass and waste industrial slag toward enhanced energy storage.

Electrolysis Synthesis of Carbides and Carbon Dioxide Capture in Molten Salts

The application of carbides in catalysis, batteries, aerospace fields, etc. has been continuously expanded and deepened, which is attributed to the diversified physicochemical properties of carbides via a tune-up of their morphology, composition, and microstructure. The emergence of MAX phases and high entropy carbides with unparalleled application potential undoubtedly further stimulates the research upsurge of carbides. The traditional pyrometallurgical or hydrometallurgical synthesis of carbides inevitably faces the shortcomings of complex process, unacceptable energy consumption, extreme environmental pollution, and beyond. The molten salt electrolysis synthesis method with the superiorities of straightforward route, high efficiency, and environmental friendliness has demonstrated its validity in the synthesis of various carbides, which naturally initiates more research. In particular, the process can achieve CO₂ capture while synthesizing carbides based on the excellent CO₂ capture capability of some molten salts, which is of great significance for carbon neutralization. In this paper, the synthesis mechanism of carbide by molten salt electrolysis, the process of CO₂ capture and carbides conversion, the latest research progress in the synthesis of binary, ternary, multi-component, and composite carbides are reviewed. Finally, the challenges, development perspectives, and research directions of electrolysis synthesis of carbides in molten salts are featured.

Recent Advances in Electrochemical-Based Silicon Production Technologies with Reduced Carbon Emission

Sustainable and low-carbon-emission silicon production is currently one of the main focuses for the metallurgical and materials science communities. Electrochemistry, considered a promising strategy, has been explored to produce silicon due to prominent advantages: (a) high electricity utilization efficiency; (b) low-cost silica as a raw material; and (c) tunable morphologies and structures, including films, nanowires, and nanotubes. This review begins with a summary of early research on the extraction of silicon by electrochemistry. Emphasis has been placed on the electro-deoxidation and dissolution-electrodeposition of silica in chloride molten salts since the 21st century, including the basic reaction mechanisms, the fabrication of photoactive Si films for solar cells, the design and production of nano-Si and various silicon components for energy conversion, as well as storage applications. Besides, the feasibility of silicon electrodeposition in room-temperature ionic liquids and its unique opportunities are evaluated. On this basis, the challenges and future research directions for silicon electrochemical production strategies are proposed and discussed, which are essential to achieve large-scale sustainable production of silicon by electrochemistry.

Extending Ag Nanoparticles as Colorimetric Sensor to Industrial Zinc Electrolyte for Cobalt Ion Detection

The direct and rapid determination of trace cobalt ion (Co²⁺) in the electrolyte of zinc smelting plants is urgently needed but is impeded by the severe interference of extremely high-concentration zinc ions in the solution. Herein, colorimetric detection of Co²⁺ by the polyvinylpyrrolidone functionalized silver nanoparticles (PVP-AgNPs) is realized in solutions with the Zn/Co ratio being high, up to (0.8-5) × 10⁴, which is located within the ratio range in industrial solution. The high concentration of Zn²⁺ induces a strong attenuation of Co²⁺-related signals in ultraviolet-visible (UV-vis) extinction spectra; nevertheless, a good linear range for detecting 1-6 mg/L Co²⁺ in 50 g/L Zn²⁺ solution is still acquired. The strong anti-interference toward other metal ions and the mechanism understanding for trace Co²⁺ detection in such a high-concentration Zn²⁺ solution are also revealed by systematic analysis techniques. The results extend the AgNPs as colorimetric sensors to industrial solutions, providing a new strategy for detecting trace-metal ions in industrial plants.

Silicate-Mediated Electrolytic Silicon Nanotube from Silica in Molten Salts

Electrochemical preparation/processing of functional silicon from abundant silica is an ideal protocol to promote sustainability of energy sectors. Such an imperative task is challenged by poor electrical conductivity of Si/SiO₂ and inadequate mass diffusion of bulk silicon. Herein, a template-free and one-step preparation of silicon nanotubes (Si-NT) from electrochemical reduction of silica in molten salts is reported. An in situ oriented growth of silicate nanorods (NRs) from silica is clarified as the key step to direct a self-template evolution of Si-NT from silica. The silicate-mediated construction of Si-based NT is versatile and successfully extended to prepare Si-NT/graphite and Ti_x Si_y -NT. Benefitting from fast longitudinal motorways for fast transport of electrons and ions along/inside NTs, an energy consumption 30% lower than industrial silicon production is achieved. When evaluated as anode of lithium ion battery, the Si-NT-based electrodes show outstanding initial Coulombic efficiency and high reversible capacity. The silicate-mediated construction of Si-based NT integrates straightforward preparation and intriguing functionality of Si-based materials, bridging a closed-loop Si-based energy infrastructure.

Scalable Synthesis of Pore-Rich Si/C@C Core-Shell-Structured Microspheres for Practical Long-Life Lithium-Ion Battery Anodes

Silicon/carbon (Si/C) composites have rightfully earned the attention as anode candidates for high-energy-density lithium-ion batteries (LIBs) owing to their advantageous capacity and superior cycling stability, yet their practical application remains a significant challenge. In this study, we report the large-scale synthesis of an intriguing micro/nanostructured pore-rich Si/C microsphere consisting of Si nanoparticles tightly immobilized onto a micron-sized cross-linked C matrix that is coated by a thin C layer (denoted P-Si/C@C) using a low-cost spray-drying approach and a chemical vapor deposition process with inorganic salts as pore-forming agents. The as-obtained P-Si/C@C composite has high porosity that provides sufficient inner voids to alleviate the huge volume expansion of Si. The outer smooth and robust C shells strengthen the stability of the entire structure and the solid-electrolyte interphase. Si nanoparticles embedded in a microsized cross-linked C matrix show excellent electrical conductivity and superior structural stability. By virtue of structural advantages, the as-fabricated P-Si/C@C anode displays a high initial Coulombic efficiency of 89.8%, a high reversible capacity of 1269.6 mAh g^-1 at 100 mA g^-1, and excellent cycle performance with a capacity of 708.6 mAh g^-1 and 87.1% capacity retention after 820 cycles at 1000 mA g^-1, outperforming the reported results of Si/C composite anodes. Furthermore, a low electrode swelling of 18.1% at a high areal capacity of 3.8 mAh cm^-2 can be obtained. When assembled into a practical 3.2 Ah cylindrical cell, extraordinary long cycling life with a capacity retention of 81.4% even after 1200 cycles at 1C (3.2 A) and excellent rate performance are achieved, indicating significant advantages for long-life power batteries in electric vehicles.

Nitrogen-Doped Carbon Networks with Consecutive Conductive Pathways from a Facile Competitive Carbonization-Etching Strategy for High-Performance Energy Storage

Recently, new carbonization strategies for synthesizing structure-controlled and high-performance carbon electrode materials have attracted great attentions in the field of energy storage and conversion. Here a competitive carbonization-etching strategy to prepare nitrogen-doped carbon polyhedron@carbon nanosheet (NCP@CNS) hybrids derived from zeolitic imidazolate framework-8 is presented. Consecutive conductive networks are constructed in the NCP@CNS hybrids during a unique carbonization-etching pyrolysis, where a competition between the formation of NCPs and CNSs exists. When the NCP@CNS hybrids are employed as supercapacitor electrodes, their hierarchically porous NCPs serve as ion-buffering reservoirs for offering fast ion transport channels, and the CNSs within hybrids not only link the NCPs together to build electron transfer pathways but also restrict the volume fluctuation of electrodes during charging and discharging process. As a result, the as-fabricated NCP@CNS electrode displays excellent electrochemical performances including a superior specific capacitance of 320 F g^-1 , a high energy density of 22.2 W h kg^-1 (5.6 W h kg^-1 for symmetric device), and a long cycle life with capacitance retention of ≈101.8% after 5000 cycles. This study opens an encouraging avenue toward the tailored synthesis of metal-organic frameworks (MOFs)-derived carbon electrodes for renewable energy storage applications and devices.

A surface-engineering-assisted method to synthesize recycled silicon-based anodes with a uniform carbon shell-protective layer for lithium-ion batteries

Yolk-shell silicon/carbon composite encapsulated by uniform carbon shell (Si@C) are becoming an effective method to mitigate volume-related issues of Si-based anodes and maintain an excellent performance for lithium-ion batteries (LIBs). However, a uniform carbon shell in Si@C is difficult to guarantee. Herein, a facile surface-engineering-assisted strategy is described to prepare Si@C composite with low-cost modified recycled waste silicon powders (RWSi) as core coated by a uniform carbon shell-protective layer derived from the pyrolysis of poly (methyl methacrylate) (PMMA) as carbon source (m-RWSi@PMMA-C). In this process, surface-engineering is performed with silane coupling agent kh550 to functionalize the RWSi particles via a silanization reaction, guaranteeing a uniform PMMA coating which will be transformed into carbon shell-protective layer after carbonization. The m-RWSi@PMMA-C electrode delivers an optimal discharge capacity of 1083 mAhg^-1 at 200 mAg^-1 after 200 cycles with an initial capacity of 3176.2 mAhg^-1 and a high initial Coulombic efficiency (ICE) of 75.6%. Based on these results, the recycled silicon-based anode with a uniform carbon shell-protective layer displays great application potential and it also brings a new perspective on silicon-based anodes via surface-engineering method for LIBs.

Stable Interface between a NaCl-AlCl3 Melt and a Liquid Ga Negative Electrode for a Long-Life Stationary Al-Ion Energy Storage Battery

Intermediate temperature NaCl-AlCl₃-based Al-ion batteries are considered as a promising stationary energy storage system due to their low cost, high safety, etc. However, such a cheap electrolyte has a critical feature, i.e., strong corrosion, which results in the short cycle life of the conventional Al-metal anode and also limits the development of the NaCl-AlCl₃-based Al-ion batteries. A noncorrosive electrolyte may be a good choice for addressing the above challenge, while it is difficult to obtain the electrolyte that has advantages of both noncorrosion and low cost. Therefore, here, we report a Ga-metal anode in the affordable NaCl-AlCl₃ electrolyte for constructing a long-life stationary Al-ion energy storage system. This featured liquid metal anode shows good alloying and dealloying processes between metallic Ga and Al, as well as renders superior stability of the interface between the electrolyte and the anode (e.g., smoothly running for over 580 h at 2 mA cm^-2). No-corrosion and no-pulverization problems appear in this novel liquid/liquid interface. Those advantages demonstrate that the liquid Ga-metal anode has a great promise for the improvement of the NaCl-AlCl₃-based Al-ion batteries for large-scale stationary energy storage applications.

Engineering Carbon Distribution in Silicon-Based Anodes at Multiple Scales

The successful commercialization of promising silicon-based anode materials has been hampered by their poor cycling stability caused by the huge volume change. Integration of the carbon matrix with silicon-based (C/Si-based) anode materials has been demonstrated to be a powerful solution to achieve satisfactory electrochemical performance. This minireview aims to outline recent developments on C/Si-based composites, with the emphasis on the importance of carbon distribution at multiple scales. In addition, the forms of the carbon framework (carbon sources and doping of heteroatoms) have been summarized. Particularly, a novel C/Si-based hybrid with carbon distributed at the atomic scale has been highlighted.

One-pot solution synthesis of carbon-coated silicon nanoparticles as an anode material for lithium-ion batteries

Carbon-coated silicon nanoparticles were synthesized via a one-pot solution method, delivering excellent performance in lithium ion batteries.

Synthesis of Porous Si/C Composite Nanosheets from Vermiculite with a Hierarchical Structure as a High-Performance Anode for Lithium-Ion Battery

Silicon nanosheets are fascinating anode materials for lithium-ion batteries because of their high specific capacities, structural stability, and fast kinetics in alloying/dealloying with Li. The nanosheets can be synthesized through chemical vapor deposition (CVD), topochemical reaction, and templating method. After coating with a carbon nanolayer, they exhibit enhanced electrochemical performance. However, it is challenging to synthesize ultrathin carbon-coated silicon nanosheets. In this work, porous silicon/carbon (pSi/C) composite nanosheets are synthesized by reducing the carbon-coated expanded vermiculite with metallic Al in the molten salts. The as-prepared pSi/C nanosheets retain the layered nanostructure of vermiculite, with a thickness of less than 50 nm. The carbon nanolayer serves as the diffusion barrier and mechanical support for the growth of mesoporous silicon nanosheets. The anode of pSi/C nanosheets achieves remarkable electrochemical performance, exhibiting a reversible capacity of 1837 mA h g^-1 at 4 A g^-1 and retaining 71.5% of the initial capacity after 500 cycles. The process can be extended to the synthesis of the pSi/C composite nanotube by using other carbon-coated silicate templates such as halloysite.