Solution-synthesized thermoelectric nanostructured materials have the potential to have lower cost and higher performance than materials synthesized by solid-state methods. Herein we present the ...synthesis of ultrathin PbTe nanowires, which are compressed by spark plasma sintering at various temperatures in the range of 405–500 °C. The resulting discs possess grains with sizes of 5–30 μm as well as grains with sizes on the order of the original 12 nm diameter PbTe nanowires. This micro- and nanostructure leads to a significantly reduced thermal conductivity compared to bulk PbTe. Careful electron transport analysis shows suppressed electrical conductivity due to increased short-range and ionized defect scatterings, while the Seebeck coefficient remains comparable to the bulk value. The PbTe nanowire samples are found unintentionally p-type doped to hole concentrations of 2.16–2.59 × 1018 cm–3. The maximum figure of merit achieved in the unintentionally doped spark plasma sintered PbTe nanowires is 0.33 at 350 K, which is among the highest reported for unintentionally doped PbTe at low temperatures.
Sodium‐ion batteries are considered as the most promising candidates for grid‐level energy storage applications due to its unique features of much lower cost and comparable energy density to lithium ...ion batteries. However, searching for suitable cathode materials with high capacity and good cycling stability are still the bottleneck issues due to the involved unmanageable phase transitions and difficult morphology control. Herein, unique fullerene‐like hollow polyhedrons of P2‐type Na0.67Ni0.15Mn0.85O2 cathode were successfully synthesized via a facile and scalable self‐template strategy, where largely enhanced electrochemical properties can be achieved compared to its bulk counterpart. It can deliver a high specific capacity of 101 mAh g−1 after 120 cycles at a rate of 100 mA g−1, reaching an excellent capacity retention of 96.8 %. The possible origins of the enhanced performance were further analyzed to be the synergistic effect of hollow interior and novel morphology of the polyhedron, leading to well exposed (002) planes, shorter diffusion path and better structural robust. Importantly, the full battery without pre‐sodiation treatment could deliver a high energy density of 133.1 Wh kg−1 based on the total mass of cathode and anode, which sheds a new light for designing high energy density sodium‐ion full batteries.
Ready for the grid: Unique fullerene‐like hollow polyhedrons of P2‐type Na0.67Ni0.15Mn0.85O2 cathode is synthesized via a facile and scalable self‐templated strategy with largely enhanced electrochemical performance originated from the synergistic effect of hollow interior and unique morphology of faceted polyhedron. More importantly, the sodium‐ion full battery based on NNMO‐FHP without pre‐sodiation treatment can deliver a high energy density of 133.1 Wh kg−1, demonstrating its great potential for grid‐level applications.
P2‐type Na0.67Ni0.33Mn0.67O2 is a promising cathode for sodium‐ion batteries with features of high specific capacity and air resistance, whereas its cycling stability and rate performance are ...dissatisfactory suffering from the disastrous P2‐O2 phase transition and Na+/vacancy ordering during sodium‐ion de/intercalation, which makes it an obstruction for future practical applications. Herein, a delicate multicomponent modulation strategy is proposed to tackle these two issues simultaneously, in which Li+ and Ti4+ are introduced to replace the Ni2+ and Mn4+, respectively, whereas the Na+ content is also designed according to the principle of charge balance. Consequently, the designed cathode (Na0.72Ni0.28Li0.05Mn0.57Ti0.10O2) can deliver an enchanting cycling stability of 80% at 1 C after 200 cycles along with a considerable rate performance of 82.7 mAh g−1 at 5 C. In situ X‐ray diffraction measurement demonstrates the destructive P2‐O2 phase transition is suppressed and converted into a P2‐Z phase transition with superior reversibility as well as smooth charge/discharge curves with better Na+/vacancy disordering. In addition, the full cell matched with hard carbon anode delivers an excellent energy density of 263.4 Wh kg−1 at 37.3 W kg−1, exhibiting great practicality. Our work presents a mean to rationally design the component of layered oxide cathode and achieve fabulous performance for sodium ion batteries.
A delicate multicomponent modulation strategy is employed on P2‐Na0.67Ni0.33Mn0.67O2 to address the P2‐O2 phase transition and Na+/vacancy ordering problems simultaneously. and Thanks to the multicomponent modulation strategy, the modified cathode Na0.72Ni0.28Li0.05Mn0.57Ti0.10O2 can show enhanced electrochemical performance in half and full cell.
The production of high-demand syngas with tunable ratios by CO2 electroreduction has attracted considerable research interest. However, it is challenging to balance the evolution performance of H2 ...and CO with wide H2/CO ratios, while maintaining high efficiency. Herein, nitrogen-coordinated hierarchical porous carbon spheres with varying phosphorus content (PxNC-T) are assembled to regulate syngas production performance. The precise introduction of P modulates the local charge distribution of nitrogen-coordinated carbons, thereby accelerating the protonation process of ∗CO2-to-∗COOH and promoting moderate H∗ adsorption. Specifically, syngas with wide H2/CO ratios (0.60–4.98) is obtained over a low potential range (−0.46 to −0.86 V vs. RHE). As a representative, P1.0NC-900 presents a remarkable current density (−152 mA cm−2) at −1.0 V vs. RHE in flow cells and delivers a decent peak power density (1.93 mW cm−2) in reversible Zn-CO2 batteries. Our work provides valuable insights into the rational design of carbon-based catalysts for CO2 reduction.
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•N-coordinated porous carbon spheres with varying P content are assembled•Precise introduction of P can modulate the local electronic properties of N-C•Syngas with wide H2/CO ratios is obtained over a low potential range•Impressive performance is achieved in both flow cells and Zn-CO2 batteries
Materials chemistry; Surface science
Bismuth sulfide (Bi2S3) is a dominant anode material for sodium-ion batteries due to its high theoretical capacity. However, extreme volume fluctuations as well as low electrical conductivity and ...reaction kinetics still limit its practical applications. Herein, we construct an abundant heterointerface of Bi/Bi2S3 by engineering the structure of Bi nanoparticles embedded on Bi2S3 nanorods (denoted as Bi–Bi2S3 NRs) to effectively solve the abovementioned obstacles. Theoretical and systematic characterization results reveal that the constructed heterointerface of Bi/Bi2S3 has a built-in electric field, significantly boosts the electrical conductivity, enhances the Na+ diffusion kinetics, and buffers the volume variation. With this modification, it can deliver long cycling life, with an ultra-high capacity of 500 mAh g−1 over 500 cycles at 1 A g−1, and outstanding rate capability, with a capacity of 456 mAh g−1 even at 15 A g−1. Moreover, a full cell can achieve a high energy density of 180 Wh kg−1 at a power density of 40 W kg−1. Our research opens up a fresh path for improving the dynamics and structural stability of metal sulfide-based electrode materials for SIBs.
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•A unique heterostructure of Bi nanoparticles embedded on Bi2S3 nanorods (NRs) is prepared via a simple strategy.•This Bi–Bi2S3 NRs heterostructure creates a powerful built-in electric field by regulating the energy band structure.•The heterostructure delivers excellent electrochemical performance in terms of cycling stability and rate capability.•A full cell assembled with a Na3V2(PO4)3/C cathode and a Bi–Bi2S3 NRs anode provides a high energy density of 180 Wh kg−1.
Owing to the specific merits of low cost, abundant sources, and high physicochemical stability, carbonaceous materials are promising anode candidates for K+/Na+ storage, whereas their limited ...specific capacity and unfavorable rate capability remain challenging for future applications. Herein, the sulfur implantation in N‐coordinated hard carbon hollow spheres (SN‐CHS) has been realized for evoking a surface‐driven capacitive process, which greatly improves K+/Na+ storage performance. Specifically, the SN‐CHS electrodes deliver a high specific capacity of 480.5/460.9 mAh g−1 at 0.1 A g−1, preferred rate performance of 316.8/237.4 mAh g−1 at 5 A g−1, and high‐rate cycling stability of 87.9%/87.2% capacity retention after 2500/1500 cycles at 2 A g−1 for K+/Na+ storage, respectively. The underlying ion storage mechanisms are studied by systematical experimental data combined with theoretical simulation results, where the multiple active sites, improved electronic conductivity, and fast ion absorption/diffusion kinetics are major contributors. More importantly, the potassium ion hybrid capacitor consisting of SN‐CHS anode and activated carbon cathode deliver an outstanding energy/power density (189.8 Wh kg−1 at 213.5 W kg−1 and 9495 W kg−1 with 53.9 Wh kg−1 retained) and remarkable cycling stability. This contribution not only flourishes the prospective synthesis strategies for advanced hard carbons but also facilitates the upgrading of next‐generation stationary power applications.
The sulfur implantation in N‐coordinated hard carbon hollow spheres (denoted as SN‐CHS) has been realized by using 2‐mercaptopyridine as S/N sources and pore swelling agent, which greatly enhances the surface‐driven capacitive process for improved K+/Na+ storage performance.
Sodium iron phosphate (NaFePO4) has attracted significant attention because of its high theoretical capacity (155 mA h g−1), remarkable structural stability, and abundant elemental composition. ...However, the electrochemical reversibility of maricite NaFePO4 is generally considered inactive. Herein, a nanoengineering strategy to activate the electrochemical activity of maricite NaFePO4 is presented. This approach involves the construction of ultrasmall maricite NaFePO4 nanoparticles encapsulated within an ultrathin carbon layer (denoted as m‐NFP@C), which greatly improves the electrochemical properties of the material. Notably, the optimized m‐NFP@C nanoparticles exhibit an impressive reversible capacity of 101.4 mA h g−1 after 100 cycles at a current density of 20 mA g−1, demonstrating a remarkable capacity retention of 90.5%. Furthermore, when coupled with the bismuth–carbon microfoam‐like compound (Bi@NC‐MF) anode, the fabricated sodium‐ion full cell exhibits exceptional cycling stability with a capacity retention of 90.6% over 250 cycles. The remarkable electrochemical performance of this material can be attributed to its excellent structural stability, ultrafine nanostructure, and uniform carbon coating, which effectively shorten the Na+ diffusion pathways, prevent the aggregation and fragmentation of nanoparticles, and enhance electronic conductivity. This work is anticipated to open up a new route for activating maricite NaFePO4 and advancing the development of polyanion‐type electrode materials.
Carbon‐coated maricite NaFePO4 nanoparticles (denoted as m‐NFP@C) are synthesized through a facile sol–gel method followed by carbonization treatment, exhibiting superior sodium‐ion storage performance. The assembled NFP‐1.8//Bi@NC‐MF full‐cell also delivers an extraordinary cycling life.
The size and shape control of amorphous nanomaterials has long been a bottleneck restricting their further development. Here, we present a general approach to synthesize more than twenty kinds of ...amorphous metal oxide nanosheets. The amorphous state of the nanosheets is determined using aberration-corrected high-resolution transmission electron microscopy and X-ray diffraction. By using extended X-ray absorption fine structure analysis, we demonstrate that amorphous nanosheets have a larger interatomic distance and a looser packing characteristic compared with crystalline counterparts. The as-prepared amorphous FeOx nanosheets are used as sodium-ion batteries anode materials, exhibiting notable performance with a specific capacity of 263.4 mAh g−1 at 100 mA g−1 and long-term cyclic stability. Significantly, a reversible amorphous-crystalline-amorphous structure transformation phenomenon during the cycling test is observed at the atomic scale.
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A general approach to synthesize >20 types of amorphous metal oxide nanosheetsThe FeOx nanosheets exhibit excellent electrochemical properties for SIB anodesA reversible amorphous-crystalline-amorphous structure transformation is observed
The size and shape control of amorphous nanomaterials has long been a bottleneck restricting further development. Here, Sun et al. present a universal and straightforward methodology for fabricating a library of amorphous metal oxide nanosheets. As anode materials for sodium-ion batteries, the FeOx nanosheets exhibit superior specific capacity and long-term cyclic stability. A reversible amorphous-crystalline-amorphous structure transformation is observed during cycling.
Lithium ion batteries (LIBs) have dominated the markets of portable electronics due to the merits of a low self‐discharge rate, high voltage platform, environmental friendliness, and portability. ...However, the limited theoretical capacity of the current commercial anode material causes unsatisfied energy density of LIBs, which falls behind the ever‐increasing demands of society. Herein, a hierarchical porous carbon nanosheet assembly is successfully constructed with simultaneous SiOx incorporation and nitrogen doping (denoted as HPCNA‐(N, Si)) through a supramolecular assembly–based one‐pot strategy followed by a calcination process. Benefitting from the unique morphology, highly porous feature, and the synergy of SiOx incorporation and nitrogen doping, the HPCNA‐(N, Si) exhibits largely enhanced Li+ storage performance when evaluated as anode material for LIBs. Specifically, it can deliver a high specific capacity of 583.0 mA h g−1 at 500 mA g−1 with a stable cycling capability (700 cycles with an average attenuation rate of 0.32% at 1000 mA g−1). The possible origins of the promising Li+ storage behavior for HPCNA‐(N, Si) are unraveled based on the cyclic voltammetry (CV) curves, where a fair capacitive contribution of 63.6% at 0.9 mV s−1 could imply fast ion transfer kinetics for superior rate and cycling performance.
Herein, a hierarchical porous carbon nanosheet assembly is reported with SiOx incorporation and nitrogen doping (denoted as HPCNA‐(N, Si)) through a supramolecular assembly–based one‐pot strategy followed by a calcination process, which exhibits enhanced Li+ storage performance as anode material.
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