Highlights
The hierarchically porous nitrogen-doped carbon (SHPNC) was fabricated by biorenewable carbon sources.
The SHPNC electrode exhibited a high specific capacity, excellent cyclic stability, ...and superior rate capability.
The asymmetric potassium-ion hybrid capacitors delivered a maximum energy density of 135 Wh kg
−1
, long lifespan with excellent capacity retention, and outstanding ultrafast charge/slow discharge performance.
Potassium-ion hybrid capacitors (KIHCs) have attracted increasing research interest because of the virtues of potassium-ion batteries and supercapacitors. The development of KIHCs is subject to the investigation of applicable K
+
storage materials which are able to accommodate the relatively large size and high activity of potassium. Here, we report a cocoon silk chemistry strategy to synthesize a hierarchically porous nitrogen-doped carbon (SHPNC). The as-prepared SHPNC with high surface area and rich N-doping not only offers highly efficient channels for the fast transport of electrons and K ions during cycling, but also provides sufficient void space to relieve volume expansion of electrode and improves its stability. Therefore, KIHCs with SHPNC anode and activated carbon cathode afford high energy of 135 Wh kg
−1
(calculated based on the total mass of anode and cathode), long lifespan, and ultrafast charge/slow discharge performance. This study defines that the KIHCs show great application prospect in the field of high-performance energy storage devices.
Highlights
The large-sheet holey graphene framework/SiO (LHGF/SiO) composite displays notably high recoverable strain, suggesting considerably improved mechanical flexibility and robustness
The ...LHGF/SiO anode with a mass loading of 44 mg cm
−2
delivers a high areal capacity of 35.4 mAh cm
−2
at current density of 8.8 mA cm
−2
and retains a capacity of 10.6 mAh cm
−2
at 17.6 mA cm
−2
The LHGF/SiO anode with an ultra-high mass loading of 94 mg cm
−2
delivers an extraordinary areal capacity up to 140.8 mAh cm
−2
, about 1–2 order of magnitude higher than those in typical commercial devices
Silicon monoxide (SiO) is an attractive anode material for next-generation lithium-ion batteries for its ultra-high theoretical capacity of 2680 mAh g
−1
. The studies to date have been limited to electrodes with a relatively low mass loading (< 3.5 mg cm
−2
), which has seriously restricted the areal capacity and its potential in practical devices. Maximizing areal capacity with such high-capacity materials is critical for capitalizing their potential in practical technologies. Herein, we report a monolithic three-dimensional (3D) large-sheet holey graphene framework/SiO (LHGF/SiO) composite for high-mass-loading electrode. By specifically using large-sheet holey graphene building blocks, we construct LHGF with super-elasticity and exceptional mechanical robustness, which is essential for accommodating the large volume change of SiO and ensuring the structure integrity even at ultrahigh mass loading. Additionally, the 3D porous graphene network structure in LHGF ensures excellent electron and ion transport. By systematically tailoring microstructure design, we show the LHGF/SiO anode with a mass loading of 44 mg cm
−2
delivers a high areal capacity of 35.4 mAh cm
−2
at a current of 8.8 mA cm
−2
and retains a capacity of 10.6 mAh cm
−2
at 17.6 mA cm
−2
, greatly exceeding those of the state-of-the-art commercial or research devices. Furthermore, we show an LHGF/SiO anode with an ultra-high mass loading of 94 mg cm
−2
delivers an unprecedented areal capacity up to 140.8 mAh cm
−2
. The achievement of such high areal capacities marks a critical step toward realizing the full potential of high-capacity alloy-type electrode materials in practical lithium-ion batteries.
Potassium-ion batteries (PIBs) are of academic and economic significance, but still limited by the lack of highly active electrode materials for de-/intercalation of large-radius K ions. Herein, an ...interconnected nitrogen/sulfur co-doped carbon nanosheep bundle (N/S-CSB) was proposed as the potassium ions storage material. The rich co-doping of nitrogen/sulfur of N/S-CNB with three-dimensional hierarchical bundled array structure yields distensible interlayer spaces to buffer the volume expansion during K
+
insertion/extraction, offers more electrochemical active sites to obtain a high specific capacity, and provides efficient channels for fast ion/electron transports. Therefore, the N/S-CSB anode achieved high reversible specific capacity of 365 mAh/g obtained at 50 mA/g after 200 cycles with a coulombic efficiency (CE) close to 100%, high rate performance and long cycle stability. Moreover, the
in-situ
Raman spectra indicated outstanding reaction kinetics of as-prepared N/S-CSB anode.
Potassium-ion hybrid capacitors (KIHCs) have attracted growing attention due to the natural abundance and low cost of potassium. However, KIHCs are still limited by sluggish redox reaction kinetics ...in electrodes during the accommodation of large-sized K+. Herein, a starch-derived hierarchically porous nitrogen-doped carbon (SHPNC) anode and active carbon cathode were rationally designed for dual-carbon electrode-based KIHCs with high energy density. The hierarchical structure and rich doped nitrogen in the SHPNC anode result in a distensible interlayer space to buffer volume expansion during K+ insertion/extraction, offers more electrochemical active sites to achieve high specific capacity, and has highly efficient channels for fast ion/electron transports. The in situ Raman and ex situ TEM demonstrated a reversible electrochemical behavior of the SHPNC anode. Thus, the SHPNC anode delivers superior cycling stability and a high reversible capacity (310 mA h g–1 at 50 mA g–1). In particular, the KIHCs assembled by the SHPNC anode and commercial active carbon cathode can deliver a high energy density of 165 W h kg–1 at a current density of 50 mA g–1 and an ultra-long cycle life of 10,000 cycles at 1 A g–1 (calculated based on the total mass of the anode and cathode).
•PEO of Zircaloy-2 is investigated in different concentrations of aluminate.•“Soft” sparks enhance the growth of the inner coating layer in dilute aluminate.•Coatings with superior wear resistance ...are formed in concentrated aluminate.•Large amount of Al2O3 besides t-ZrO2 provides the superior wear resistance.
Plasma electrolytic oxidation of Zircaloy-2 has been investigated in dilute and concentrated aluminate electrolytes, under a pulsed-bipolar current regime, in order to develop coatings of high wear resistance. Coating growth kinetics, cell potential-time responses and discharging behaviours depend significantly on the electrolyte concentration. The coatings formed in dilute aluminate electrolyte reveal a three-layered structure, with pancake structures at the coating surfaces. “Soft sparks” occur during PEO in dilute aluminate electrolyte, causing a relatively fast growth of the inner layer and resulting in a large amount of alumina-enriched material beneath the pancake structures, and hence an increased wear resistance of the coating. In contrast, more homogenous coatings, free of pancakes, result with the concentrated electrolyte. The main phase in the coatings is t-ZrO2, with γ-Al2O3 also present in coatings formed in the latter electrolyte. The coatings formed in the concentrated electrolyte display a high wear resistance, even for thin coatings formed for short times, which is attributed to the relatively high alumina content of the coatings.
This study mainly investigated the effects of silicate concentration at the range of (16g/L to 56g/L) on the plasma electrolytic oxidation of Zircaloy-2 in potassium hydroxide/sodium silicate ...electrolytes in detail, including the growth behavior, wear and corrosion resistance of as-obtained ZrO2/SiO2 alloyed coatings. It was found that the coating thickness increased continuously on increasing the silicate concentration in electrolyte. Besides, the amount of t-ZrO2 in the coatings increased with increase of silicate concentration in electrolyte, while the amount of m-ZrO2 decreased. Comparative studies have shown that the coatings formed in electrolyte with high silicate concentration possessed superior wear and corrosion performance, which could be ascribed to heavy silica deposition associated with the presence of t-ZrO2 stabilized by SiO2. The results may provide guidance for obtaining high performance of ZrO2/SiO2 alloyed coatings. Besides, it is believed that the presence of Si species in zirconia endows the coatings with enhanced bioactivity like bioactive glasses and ceramics coatings and we envision that the as-prepared ZrO2/SiO2 alloyed coatings have great potential for biological applications.
Este estudio investigó en detalle los efectos de la concentración de silicato en el rango de (16 a 56g/l), en la oxidación electrolítica por plasma de Zircaloy-2 en electrolitos de hidróxido de potasio/silicato de sodio, incluido el modo de crecimiento y la resistencia al desgaste y a la corrosión de los recubrimientos de aleaciones de ZrO2/SiO2 obtenidos. Se descubrió que el espesor del recubrimiento aumentaba continuamente al aumentar la concentración de silicato en el electrolito. Además, la cantidad de t-ZrO2 en los recubrimientos aumentó con el aumento de la concentración de silicato en el electrolito, mientras que el contenido de m-ZrO2 disminuía. Estudios comparativos han demostrado que los recubrimientos formados en electrolito con alta concentración de silicato poseían mayor resistencia al desgaste y a la corrosión, que podría atribuirse a una fuerte deposición de sílice asociada con la presencia de t-ZrO2 estabilizado por SiO2. Los resultados pueden proporcionar guía para obtener un alto rendimiento de los recubrimientos con aleaciones ZrO2/SiO2. Además, se cree que la presencia de especies de Si en la circona dota a los recubrimientos con una bioactividad mejorada como recubrimientos cerámicos o vítreos bioactivos, y prevemos que los recubrimientos de aleaciones ZrO2/SiO2 preparados tienen un gran potencial para aplicaciones biológicas.
Exploring electrode materials with attractive specific capacity and prominent cyclic durability is of the essence for promoting lithium ion batteries (LIBs). In2O3 has shown an extraordinary promise ...for LIBs with advantageous gravimetric capacity (theoretically 965 mA h g−1) and low working voltage. However, In2O3 still suffers from the inherent weaknesses of metal oxides in practical application, especially low conductivity and incorrigible volume expansion upon the cycling process. Here, we demonstrate the architecture of metal–organic framework (MOF)‐derived In2O3 nanocrystals/hierarchically porous nitrogen‐doped carbon composite (In2O3/HPNC) for ultra‐stable LIBs anode. This hierarchically porous structure (micro/meso/macro‐pores) with nitrogen doping not only ensures exceptional mechanical strength and accommodates the volume expansion of In2O3 nanocrystals, but also offers electrons and lithium ions efficient interpenetrating pathways to migrate rapidly during charge/discharge processes. Thus, In2O3/HPNC exhibits excellent cyclic stability with a high specific capacity of 623 mA h g−1 over 2000 cycles at 1000 mA g−1, corresponding to an ultra‐low specific capacity decay of 0.017% per cycle (the best among the In2O3‐based anode for LIBs), and outstanding rate performance, suggesting a critical step toward achieving long‐life and high‐rate LIBs in practical devices.
The In2O3 nanocrystals/hierarchically porous nitrogen‐doped carbon was derived from indium‐based MOF. As anode for LIBs, the unique hierarchical structure and porous carbon with nitrogen doping accommodates the volume expansion of In2O3 nanocrystals and ensures the rapid migration of electrons and lithium ions, thus can further guarantee excellent cyclic stability and outstanding rate performance.
Commercial Cu and Al current collectors for lithium‐ion batteries (LIBs) possess high electrical conductivity, suitable chemical and electrochemical stability. However, the relatively flat surface of ...traditional current collectors causes weak bonding strength and poor electrochemical contact between current collectors and electrode materials, resulting in potential detachment of active materials and rapid capacity degradation during extended cycling. Here, we report an ultrafast femtosecond laser strategy to manufacture hierarchical micro/nanostructures on commercial Al and Cu foils as current collectors for high‐performance LIBs. The hierarchically micro/nanostructured current collectors (HMNCCs) with high surface area and roughness offer strong adhesion to active materials, fast electronic delivery of entire electrodes, significantly improving reversible capacities and cyclic stability of HMNCCs based LIBs. Consequently, LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode with Al HMNCC generated a high reversible capacity after 200 cycles (25% higher than that of cathode with Al CC). Besides, graphite anode with Cu HMNCC also maintained prominent reversible capacity even after 600 cycles. Moreover, the full cell assembled by graphite anode with Cu HMNCC and NCM523 cathode with Al HMNCC achieved high reversible capacity and remarkable cycling stability under industrial‐grade mass loading. This study provides promising candidate for achieving high‐performance LIBs current collectors.
The hierarchically micro/nanostructured Al/Cu current collectors (Al/Cu HMNCCs) were obtained from ultrafast femtosecond laser strategy. As positive and negative current collectors for LIBs, the unique hierarchical structures with high surface area and roughness offer strong adhesion to active materials and ensure fast electronic delivery of entire electrodes, and thus can further guarantee excellent cycling stability under industrial‐grade mass loading.
Plasma electrolytic oxidation (PEO) of AZ31 magnesium alloy under pulsed bipolar constant current regimes has been carried out in a silicate–hexametaphosphate electrolyte without and with the ...suspension of SiC nanoparticles. The coatings were characterized by eddy current method, X-ray diffraction (XRD), scanning electron microscopy (SEM), dry sliding wear and electrochemical tests. Higher growth rates were found for the coatings formed with the presence of nanoparticles. The incorporation of SiC nanoparticles into the coatings has been verified by XRD and SEM, and the incorporated particles were found to distribute relatively uniformly along the coating depth. “Weak sites” existed in the SiC free coatings, which significantly lowered the wear performance of the coatings. In contrast, “weak sites” are not found in the coatings with the incorporation of SiC nanoparticles, resulting in an excellent wear performance of the coatings. The applied current densities of the PEO processes also affect the performance of the coatings, with higher wear rates for the coating prepared under higher current densities. All the coatings show improved corrosion resistances.
•PEO of AZ31 magnesium alloy without and with the incorporation of SiC nanoparticles•Thicker coatings are formed in electrolytes with the presence of SiC nanoparticles.•SiC nanoparticles incorporated relatively uniformly along the coating depth.•Weak points in the SiC free coatings drastically reduced their wear resistance.•The incorporation of nanoparticles greatly improved wear resistance of the coatings.
The fate of volatile organic compounds (VOC) vapors in the unsaturated zone is the basis for evaluating the natural attenuation potential and vapor intrusion risk. Microcosm and column experiments ...were conducted to study the effects chemical speciation and soil types/properties on the fate of petroleum VOCs in unsaturated zone. The biodegradation and total attenuation rates of the seven VOCs obtained by microcosm experiments in black soil and yellow earth were also generally higher than those in floodplain soil, lateritic red earth, and quartz sand. The VOC vapors in floodplain soil, lateritic red earth, and quartz sand showed slow total attenuation rates (<0.3 d−1). N-pentane, methylcyclopentane, and methylcyclohexane showed lower biodegradation rates than octane and three monoaromatic hydrocarbons. Volatilization into the atmosphere and biodegradation are two important natural attenuation paths for VOCs in unsaturated soil columns. The volatilization loss fractions of different volatile hydrocarbons in all five unsaturated soils were generally in the order: n-pentane (93.5%–97.8%) > methylcyclopentane (77.2%–85.5%) > methylcyclohexane (53.5%–69.2%) > benzene (17.1%–73.3%) > toluene (0–45.7%) > octane (1.9%–34.2%) > m-xylene (0–5.7%). The fractions by volatilization into the atmosphere of all seven hydrocarbons in quartz sand, lateritic red earth, and floodplain soil were close and higher compared to the yellow earth and black soil. Overall, this study illustrated the important roles chemical speciation and soil properties in determining the vapor-phase transport and natural attenuation of VOCs in the unsaturated zone.
Display omitted
•Volatilization and biodegradation are two main vapor natural attenuation pathways.•Soil texture and SOM content affect vapor fate and attenuation in the vadose zone.•Hydrocarbons with less carbon atoms have stronger volatilization loss.•Strong sorption and biodegradation enhanced vapor mass loss.
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