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Fullerene (C70) molecules are assembled into microrods, and calcination breaks the carbon cages into defect-rich porous carbon microrods that show excellent ORR performance, comparable to commercial Pt/C.

Phosphorus doping Ni83 exhibits an extraordinary capacity retention of 80.2% after 500 cycles between 2.7 and 4.3 V at 1C under 60 °C.

Tungsten carbide (W2C) has emerged as a potential alternative to noble-metal catalysts toward hydrogen evolution reaction (HER) owing to its Pt-like electronic configuration. However, unsatisfactory activity, dilatory electron transfer, and inefficient synthesizing methods, especially for nanoscale particles, have severely hindered its large-scale applications. Herein, a novel heterostructure composed of W2C and tungsten phosphide (WP) embedded in nitrogen-decorated carbon (W2C/WP@NC) was constructed as an efficient HER electrocatalyst. The as-prepared W2C/WP@NC catalyst exhibits remarkable electrocatalytic activity and robust durability toward HER both in acids and bases. More notably, the W2C/WP@NC catalyst demonstrates low overpotentials of 116.37 and 196.2 mV to afford a current density of 10 mA cm-2 and reveals slight potential decays of about 6.4 and 7.64% over 12 h continuous operation in bases and acids, respectively. The overall water-splitting performance was further evaluated using the W2C/WP@NC catalyst as the cathode and commercial RuO2 as the anode in an electrolyzer, which can realize an overall current density of 10 mA cm-2 and maintain long durability of more than 12 h with a small cell voltage of 1.723 V. This work opens up new opportunities for exploring cost-efficient electrocatalysts in sustainable energy conversion.

Developing large capacity electrode with fast charging capability has always been our goal for high-energy Li-ion batteries. To design a superior electrode, large enough capacity, suitable voltage plateau and good ionic/electronic conductivity need to be taken into account at the same time. Herein, by fusing the semiconductor Ge into nonmetal P, a novel metallic GexP60-x solid solution with wide range tuneable region is proposed, which is proved a kind of Ge-P binary alloy instead of typical ionic/covalent compound. The synthesized GexP60-x is not a metal phophide, which is in contradictory to our conventional view. Attributed from its unique phosphorus-like layered structure, those GexP60-x alloys possess a high conductivity (∼2.4 × 106 S/m). More specially, the Ge-P interaction is not a strong covalent bond like metal phosphides and thereby, the conversion reaction process based on chemical bond breaking in metal phosphides would not take place in those GexP60-x alloys, being replaced by alloying-type mechanism only. Therefore, such GexP60-x alloys are the first ones which can simultaneously exhibit both large capacity (>1800 mAh/g), unexpected high reversibility (ICE>90%) and suitable voltage plateau (∼0.5 V), delivering 770 mAh/g within 15 min with low yet safe voltage for fast-charging battery. This discovery that nonmetallic and semiconductor elements can form conductive alloys based on solid solution chemistry injects fresh blood into high-performanced anode families and offers a new strategy for material design toward advanced fast charging electrodes for energy storage.

Fe-N-C represents the most promising non-precious metal catalysts (NPMCs) for the oxygen reduction reaction (ORR) in fuel cells, but often suffers from poor stability in acid due to the dissolution of metal sites and the poor oxidation resistance of carbon substrates. In this work, silicon-doped iron-nitrogen-carbon (Si/Fe-N-C) catalysts were developed by in situ silicon doping and metal-polymer coordination. It was found that Si doping could not only promote the density of Fe-N

As two important aspects in creativity, creative performance and evaluation are influenced by many individual and contextual factors. One of such factors is feedback. Past research has also found t...

Aqueous zinc-ion batteries (ZIBs) with cost-effective and safe features are highly competitive in grid energy storage applications, but plagued by the sluggish Zn2+ diffusion kinetics and poor cyclability of cathodes. Herein, a one-stone-two-birds strategy of La3+ incorporation (La-V2O5) is developed to motivate Zn2+ insertion/extraction kinetics and stabilize vanadium species for V2O5. Theoretical and experimental studies reveal the incorporated La3+ ions in V2O5 can not only serve as pillars to expand the interlayer distance (11.77 A) and lower the Zn2+ migration energy barrier (0.82 eV) but also offer intermediated level and narrower band gap (0.54 eV), thus accelerating the electron/ion diffusion kinetics. Importantly, the steadily doped La3+ ions effectively stabilize the V-O bonds by shortening the bond length, thereby inhibiting vanadium species dissolution. Therefore, the resulting La-V2O5-ZIBs deliver an exceptional rate capacity of 405 mA h g-1 (0.1 A g-1), long-term stability with 93.8% retention after 5000 cycles (10 A g-1), and extraordinary energy density of 289.3 W h kg-1, outperforming various metal-ions-doped V2O5 cathodes. Moreover, the La-V2O5 pouch cell presents excellent electrochemical performance and impressive flexibility and integration ability. The strategies of incorporating rare-earth-metal ions provide guidance to other well-established aqueous ZIBs cathodes and other advanced electrochemical devices.

Structurally ordered L10-PtM (M = Fe, Co, Ni, etc) intermetallic nanocrystals (iNCs), benefiting from the chemically ordered structure and higher stability, are one of the best electrocatalysts used for PEMFC. However, their practical development is greatly plagued by the challenge that high-temperature annealing (> 700 °C) has to be used for realizing disorder-order phase transition (DOPT) due to the high activation barrier (Ea), which always leads to severe particle sintering, morphology change, and makes it highly challenging for gram-scale preparation of desirable PtM iNCs. Here, we report a general low-melting-point metal induced bond strength weakening strategy to promote DOPT of PtM (M = Ni, Fe, Cu, Zn) alloy catalysts. We demonstrate that the introduction of Sn can reduce DOPT temperature to a record-low temperature (≤ 450 °C), which enables ten-gram-scale preparation of high-performance L10-PtM iNCs. X-ray spectroscopic studies, in-situ electron microscopy and theoretical calculations reveal that the Sn-facilitated DOPT mechanism at record-low temperature involves the weakened bond strength and reduced Ea via Sn doping, the formation and fast diffusion of low coordinated surface free atom, and subsequent L10 nucleation. Most importantly, the 15% Sn-doped L10-PtNi iNCs display outstanding performance in H2-air fuel cells with a high peak power density of 1.45 W cm-2 for Pt alloy catalysts and less than 25% activity loss after 30000 cycles at a quite low cathode Pt loading amount of 0.12 mg¬Pt cm-2, representing as one of the most efficient cathodic electrocatalyst for PEMFCs.

The small energy density and chemomechanical degradation of layered manganese oxide limit practical application to sodium-ion batteries (SIBs). Typically, Na

The LiNi

Due to climate variation and global warming, utilization of renewable energy becomes increasingly imperative. Rechargeable potassium-ion batteries (PIBs) have lately attracted much attention due to their earth-abundance and cost-effectiveness. Because soft carbon materials are cheap, abundant, and safe, extensive feasible research studies have indicated that they could become promising anode materials for PIBs. In spite of gaining achievements, fundamental questions regarding effects of the basic structure unit inside soft carbon on potassium storage potential have not been sufficiently addressed yet. Here, a series of soft carbon pyrolyzed from 900 to 2900 °C were systematically and quantitatively characterized by combining Raman spectroscopy, near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, X-ray pair distribution function analysis, and advanced evaluation of wide-angle X-ray scattering data. All these characterizations reveal structural details of soft carbon with increasing pyrolysis temperature. Our results show that the potassium storage behavior, especially the potential plateau is closely correlated to non-uniformity in interlayer distance and defect concentration in soft carbon, which is further confirmed by reverse Monte Carlo (RMC) modeling and density functional theory calculation. On the basis of these results, optimizing strategies are discussed to design an advanced soft carbon anode. This work provides significant insights into the structure engineering of soft carbon for high-performance rechargeable PIBs.

Lithium-sulfur (Li-S) batteries have been regarded as an important candidate for next-generation energy storage devices due to their low cost and high theoretical energy density. However, several f...

For reaching high-performance of electrode materials, it is generally believed that understanding the structure evolution and heterogeneous alignment effect is the key. Presently, a very simple and universally applicable self-healing method is investigated to prepare defect-free Prussian blue analogs (PBAs) that reach their theoretical capacity as cathode materials for sodium-ion batteries (SIBs). For direct imaging of the local structure and the dynamic process at the atomic scale, we deliver a fast ion-conductive nickel-based PBA that enables rapid Na+ extraction/insertion within 3 minutes and a capacity retention of nearly 100% over 4000 cycles. This guest-ion disordered and quasi-zero-strain nonequilibrium solid–solution reaction mechanism provides an effective guarantee for realizing long-cycle life and high-rate capability electrode materials that operate via reversible two-phase transition reaction. Unconventional materials and mechanisms that enable reversible insertion/extraction of ions in low-cost metal–organic frameworks (MOFs) within minutes have implications for fast-charging devices, grid-scale energy storage applications, material discovery, and tailored modification.

Ni-rich ternary layered oxides represent the most promising cathodes for lithium ion batteries (LIBs) due to their relatively large specific capacities and high energy/power densities. Unfortunately, their inherent chemical instability and surface side reactions during the charge/discharge processes lead to rapid capacity fading and poor cycling life, which seriously restrict their practical applications. Herein, we report a simple dual-modification strategy for preparing LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode materials by Li2SnO3 surface coating and Sn4+ gradient doping. The gradient Sn doping stabilizes the layered structure due to the strong Sn–O covalent bond and relieves the Li+/Ni2+ cation disorder by the partial oxidation of Ni2+ to Ni3+. Besides, the ionic and electronic conductive Li2SnO3 coating serves as a protective layer to eliminate the side reactions with electrolyte/air. In LIB testing, the dual-modified NCM622 cathode with 2% Sn delivers an enhanced cycling performance with 88.31% capacity retention after 100 cycles from 3.0 to 4.5 V at 1C compared to the bare NCM622. Meanwhile, the dual-modified NCM622 shows an improved reversible capacity of 136.2 mA h g−1 at 5C and enhanced electrode kinetics. The dual-modification strategy may enable a new approach to simultaneously relieve the interfacial instability and bulk structure degradation of Ni-rich cathode materials for high energy density LIBs.

The rational design of the electronic properties and geometric structure of the carbon matrix is an effective strategy to develop high-performance carbon-based electrocatalysts toward the oxygen-reduction reaction (ORR). Herein, hollow carbon nanospheres are synthesized using fullerene (C60) and ethylenediamine, which then form nitrogen and sulfur co-doped porous hollow carbon nanospheres (N,S-PHCNSs) via direct pyrolysis in the presence of sulfur. The decomposition of fullerenes provides carbon matrix defects, and the use of sulfur effectively modifies the contents and the configurations of the N species in the N,S-PHCNSs along with successful sulfur doping. The optimal N,S-PHCNSs exhibit an excellent ORR performance that is comparable to commercial Pt/C, which is further confirmed by Zn–air batteries. Theoretical calculations suggest that graphitic-N and thiophene-S co-doped pentagon defects can greatly elevate the ORR activity. This work not only presents a facile and effective strategy to regulate the electronic properties of the carbon matrix but also provides useful guidance for the rational design of advanced carbon-based electrocatalysts.

The development of highly efficient metal-free electrocatalysts for the oxygen reduction reaction (ORR) has attracted great attention for the creation of electrochemical energy devices. In this study, one-dimensional (1 D) fullerene nanofibers prepared from liquid-liquid interfacial precipitation are first fabricated into fullerene-derived carbon nanofiber films (FCNFs) through a simple filtration procedure. Then, pyrolysis of the FCNFs in the presence of ammonia and sulfur produces N- and S-co-doped porous carbon nanofiber films (N,S-PCNFs). As excellent metal-free electrocatalysts for the ORR, N,S-PCNFs exhibit remarkable catalytic activity, superior stability, and excellent methanol tolerance in both alkaline and acidic solution. Such a high ORR performance benefits from the robust porous nanofiber network structure with high concentrations of active N- and S- groups and abundant defects. Notably, upon practical use of N,S-PCNFs as catalysts in Zn-air batteries, a high power density and a large operating voltage are achieved, with a performance comparable to that of the commercial Pt/C catalyst. This work presents a facile strategy for the creation of a new class of energy nanomaterials based on fullerenes, demonstrating their practical uses in electrocatalytic ORR processes and Zn-air batteries.

Prussian Blue Analogs (PBAs) such as copper hexacyanoferrate (CuHCF) are traditional intercalation cathodes for rechargeable Na-ion batteries. However, the electrochemical performance of these PBAs suffers from insufficient activation and sharp performance deterioration. Here, the insufficient electrochemical activity and frame deformation issues in the CuHCF cathodes were investigated to enhance their specific capacity and improve their cycling stability. The high-crystallinity CuHCF nanosheets (CuHCF-P) with low-water-content were synthesized by a pyrophosphate-assistant co-precipitation method. It has a highly reversible 1.5-Na insertion/desertion capability with a specific capacity of ~120 mAh g−1 at 0.1 C, which is the highest among all the CuHCF cathodes reported. First-principle study and XPS detection demonstrate that both Cu and Fe are redox-active centers in CuHCF-P cathode, which facilitates a high Na+ storage capability. And the decrease of water content in CuHCF framework increases Fe/Cu 3d-orbital occupy-sites, which activates both of the transition-metals. Furthermore, the full cells fabricated with as-prepared CuHCF-P cathode and commercial hard carbon anode exhibit excellent performances with a reversible capacity of 109 mAh g−1 at 0.1 C over 200 cycles.

Solid-state electrolytes (SSEs) with high ionic conductivities are the key components in solid-state batteries, and the ionic conductivities of SSEs are strongly related to their underlying crystal...

Morphology and crystal facet controlled Cu2O nanocrystals (NCs) including cubic Cu2O (c-Cu2O) NCs with {100} facets, rhombic dodecahedral Cu2O (d-Cu2O) NCs with {110} facets, and concave octahedral...

P2-type Na2/3Ni1/3Mn2/3O2 (P2-NaNM) is a promising cathode material for practical applications in Na-ion batteries due to its high capacity. However, the rearrangement of Na+/vacancy order and cathodic charge order across the Na extraction/intercalation and structural rearrangements of P2-NaNM at high voltages result in rapid capacity fading and insufficient rate capability. Here, a combined structural modulation strategy was presented to solve these challenges via reducing the Na layers spacing through substituting Na sites by Mg ions while simultaneously stabilizing the transition metal (TM) layers through Mg/Ti co-doping. Benefited from the symbiotic effect, P2-NaNM exhibits a significantly enhanced cycling stability and rate capability in the voltage range of 3.0–4.4 ​V. We further revealed that Mn remains Mn4+ while Ni2+ becomes Ni3+ at the surface of Mg/Ti co-substituted P2-NaNM upon charge/discharge process.

The sluggish kinetics of lithium polysulfides (LiPS) transformation is recognized as the main obstacle against the practical applications of the lithium-sulfur (Li-S) battery. Inspired by molybdoenzymes in biological catalysis with stable Mo-S bonds, porous Mo-N-C nanosheets with atomically dispersed Mo-N2/C sites are developed as a S cathode to boost the LiPS adsorption and conversion for Li-S batteries. Thanks to its high intrinsic activity and the Mo-N2/C coordination structure, the rate capability and cycling stability of S/Mo-N-C are greatly improved compared with S/N-C due to the accelerated kinetics and suppressed shuttle effect. The S/Mo-N-C delivers a high reversible capacity of 743.9 mAh g-1 at 5 C rate and an extremely low capacity decay rate of 0.018% per cycle after 550 cycles at 2 C rate, outperforming most of the reported cathode materials. Density functional theory calculations suggest that the Mo-N2/C sites can bifunctionally lower the activation energy for Li2S4 to Li2S conversion and the decomposition barrier of Li2S, accounting for its inherently high activity toward LiPS transformation.