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The in situ generated Li22Sn5 nanoparticles exposed in the holes after Li stripping can guide the stripped Li to deposit back onto the previous stripping sites by regulating the local current density of the electrode surface.

To inhibit the agglomeration of tin-based nanomaterials and simplify the complicated synthesis process, a facile and eco-friendly self-formed template method is reported to synthesize tin submicron spheres dispersed in nitrogen-doped porous carbon (Sn/NPC) by pyrolysis of a mixture of disodium stannous citrate and urea. The vital point of this strategy is the formation of Na2CO3 templates during pyrolysis. This self-formed Na2CO3 acts as porous templates to support the formation of NPC. The obtained NPC provides good electronic conductivity, ample defects, and more active sites. Serving as anode for Li-ion batteries, the Sn/NPC electrode obtains a stable discharge capacity of 674.1 mAh/g after 150 cycles at 0.1 A/g. Especially, a high discharge capacity of 331.2 mAh/g can be achieved after 1100 cycles at 3 A/g. Additionally, a full cell coupled with LiCoO2 as cathode yields a discharge capacity of 524.8 mAh/g after 150 cycles at 0.1 A/g. In-situ XRD is implemented to investigate the alloying/dealloying reaction mechanisms. Density functional theory calculation ulteriorly explicates that NPC heightens intrinsic electronic conductivity, and NPC especially pyrrolic-N and pyridinic-N doping facilitates the Li-adsorption ability. Climbing image nudged elastic band method reveals low Li+ diffusion energy barrier in presence of N atoms, which accounts for the terrific electrochemical properties of Sn/NPC electrode.

The main obstacles to the development of manganese-based oxide anode materials for lithium-ion batteries (LIBs) are inherently low conductivity and sluggish electrochemical kinetics. In this work, we propose a strategy of introducing oxygen vacancies (Vo) on the surface of nanostructure at room temperature and atmospheric pressure to improve the electrochemical performance of anode materials. Porous MnO2 spheroids with 11.2% Vo are fabricated by a ball milling method using commercial electrolytic MnO2. The as-synthesized MnO2 is composed of 20–30 nm nanoparticles. The optimized MnO2 shows an excellent rate capability of 350 mAh g−1 at 6.4 A g−1 and high specific capacity of 1200 mAh g−1 after 650 cycles under 2 A g−1. The boosted electrochemical performance is attributed to the porous hierarchical structure and the appropriate Vo concentration involved in the MnO2. In addition, the enhanced Li+ diffusion coefficient is demonstrated through the kinetics analysis. The approach provides a facile route via tunable Vo concentration for improving the electrochemical performance of manganese-based oxide anode materials for LIBs. • The porous MnO2 spheroids with tunable Vo concentrate were synthesized by a ball milling method. • The MnO2 spheroids are composed of 20-30 nm nanoparticles. • The MnO2 spheroids exhibit an excellent rate performance and cycling stability. • The ball mill is facile, environmentally friendly, economical for the mass industrial scale.

To break the stereotype that silica can only be reduced via a magnesiothermic and aluminothermic method at low-temperature condition, the novel strategy for converting silica to SiO

The introduction of structural water in cathode materials of zinc-ion batteries can reduce electrostatic interactions to promote zinc-ion diffusion. However, it is difficult to introduce structural...

Exploring metal-free ultrabroad-band electromagnetic absorption materials is of great significance in practical application and theoretical research, which is, however, still challenging. Constructing hierarchical structures and seeking metal-free magnetic materials could be feasible ways to realizing stable, lightweight and metal-free ultrabroad-band electromagnetic absorption. In this work, pomegranate like polypyrrole/nanodiamond hierarchical structures, which could achieve metal-free ultrabroad-band electromagnetic absorptions, are synthesized through in situ polymerization. The optimal reflection loss peak reaches −53 dB at 10.5 GHz and the effective bandwidth below −10 dB could achieve 12.2 GHz, realizing 5.8–18 GHz full-coverage at a single thickness of 4.2 mm. The ultrabroad-band electromagnetic absorption results mainly from the π-p hybridization induced nanodiamond surface defect state, the multiple polarizations and interfaces, as well as the biomimetic pomegranate like hierarchical structures leading to the synergistic magnetic and dielectric dissipations. This work provides referencing path for designing metal-free ultrabroad-band electromagnetic absorption materials.

Amorphization is considered to be an effective way to enhance the electrochemical performances of electrode materials due to the existence of isotropy and numerous defects. Herein, an amorphous hierarchically structured MnO2/acetylene black (a-MnO2/AB) composite is successfully fabricated via a redox method and subsequent mechanical ball milling. The a-MnO2/AB composite is composed of approximately 300 nm flower-like amorphous MnO2 submicron spheres and acetylene black particles with a diameter of about 50 nm. The a-MnO2/AB electrode exhibits an initial coulombic efficiency of 73.2%, excellent rate capabilities of 318 mA h g-1 at 9.6 A g-1, and high specific capacity retention of 1300 mA h g-1 after 300 cycles at 1 A g-1. The amorphous structure can provide more channels for rapid lithium-ion transmission due to the disorder and defects, and the ion-diffusion coefficient (∼5 × 10-7 cm2 s-1) is higher than those of crystalline materials. Due to the strong interactions (Mn-O-C bonds) between MnO2 and AB as a result of the ball milling, the composite shows low charge transport resistance and small volume changes during the discharging/charging process. This work provides a facile route for the construction of amorphous hierarchically structured Mn-based oxides as anodes for lithium-ion batteries (LIBs).

Pseudocapacitive lithium storage is an effective way to promote the improvement of electrochemical performance for lithium ion batteries. However, the intrinsically sluggish lithium ionic diffusion and the low electronic conductivity of TiO2 limit its capability of pseudocapacitive behavior with fast surface redox reaction. In this work, TiO2 quantum dots confined in 3-dimensional carbon framework have been synthesized by a facile process of reverse microemulsion method combined with heat treatment. The obtained composites effectively combine electrochemical redox with surface pseudocapacitive, showing excellent electrochemical properties. An ultra-high discharge capacity of 370.5 mAh/g can be retained after 200 cycles at a current density of 0.1 A/g. Ultra-long life extends to 10,000 cycles with an average capacity loss of as low as 0.00314% per cycle can be obtained at a high current density of 5.0 A/g, due to the high pesudocapacitance contribution of fast surface redox reaction. Furthermore, the practice application of the obtained electrode is also investigated in a full cell with LiCoO2 as the cathode and a high capacity retention of 93.5% is maintained after 100 cycles at the current density of 0.1 A/g.

Controlling lithium dendrites growth and alleviating the volume expansion of lithium metal anodes are two key factors to develop high energy density lithium metal batteries. In this work, a planar Cu collector was modified by coating carbonized ZIF-67 as the bottom layer and ZIF-67 as the top layer to form an insulating–conductive double-layer configuration of the electrode (denoted as ICDL/Cu). Due to the insulating properties and high specific surface area of ZIF-67, lithium can be homogeneously deposited on the bottom layer through the top layer. The bottom layer carbonized ZIF-67 with lithiophilic Co nanoparticles and porous polyhedron are conducive to homogeneous deposition of lithium with reduced local current density. Such a porous structure ensures a low volume expansion during the lithium plating/stripping process. The symmetrical cell of ICDL/Cu–Li achieves a long cycling lifetime (more than 1100 h) with a low voltage hysteresis (11 mV) at 1 mA cm−2 for a plating/stripping capacity of 1 mA h cm−2. As a proof of concept, full cells based on ICDL/Cu–Li‖LiFePO4 deliver excellent rate performance and cycling stability compared with the bare Li‖LiFePO4 one, indicating that the unique ICDL configuration is promising for practical applications.

Green synthesis of porous anode materials with high performance and low cost remains a great challenge for the lithium-ion battery industry at present. Herein, we propose a green strategy to synthesize Sn submicron spheres/porous carbon (denoted as Sn/PC) composites by the direct carbonization of disodium stannous citrate, which is composed of Sn submicron spheres supported by porous carbon. Self-generated Na2CO3 during carbonization serves as the template to support the formation of porous carbon. The obtained porous carbon can efficaciously constrain the aggregation of Sn and prevent the volume expansion of Sn submicron spheres. Such particular structural characteristics endow the Sn/PC electrode with high discharge capacity (588 mA h g−1 after 200 cycles at 100 mA g−1) and long cycle life (431.8 mA h g−1 after 2000 cycles at 1200 mA g−1). Meanwhile, the full cell paired with the LiCoO2 cathode affords a high discharge capacity of 511.4 mA h g−1. The in-depth insights into the lithium storage mechanisms of the electrode are investigated by in situ XRD technique. The conductivity performance for the heterointerface of Sn and C is systematically studied by density functional theory calculations. This green strategy can initiate new horizons for fabricating other anode materials with conspicuous volume expansion.

TiO2 as the promising anode material candidate of sodium-ion battery suffers from poor conductivity and slow ion diffusion rate, which severely hampers its development. Highly compacted TiO2/C microspheres without inner pores/tunnels are synthesized by a very facile one-pot rapid processing method based on novel in-situ surface-confined inter-growth mechanism. This highly compacted TiO2/C microspheres exhibit an excellent electrochemical performance of reversible Na+ storage despite with relatively large particle/aggregation size from submicrometer to micrometer. An outstanding cycling stability extending to 10,000 cycles is gained with a high retention capacity of 140.5 mAh g−1 at a current rate of 2 A g−1. An ultra-high reversible capacity of 362 mAh g−1 close to its theoretic specific capacity is obtained at a current rate of 0.05 A g−1. The successful combination of highly compacted structure with large particle size, excellent electrochemical performance as well as rapid cost-effective preparing process might provide a potential industrial approach for efficiently synthesizing electrode materials for Na ion batteries.

Single-crystal precursor of hybrid oxides NiO–MnCo2O4–Ni6MnO8 (SCNCM) is synthesized via an improved continuous two-step spray pyrolysis system (CTSP). This kind of mixed oxide is to be regarded as an ideal precursor for the single-crystal Ni-rich Li[Ni[Formula: see text]Co[Formula: see text]Mn[Formula: see text]]O2 cathode materials (SCLNCM). The new pilot plant (30 t/a), method, and chlorate in this work could extremely improve the lengthy process, reducing segregation of metal element, excessive sintering temperature, high water consumption, non-polluting, and production efficiency of the SCLNCM. The resulting SCLNCM powders have a type of fine particle size and porous structure with a typical [Formula: see text]-NaFeO2 lamellar structure. It also has a type of better cyclic stability, safety, rate capability, crystallinity, and surface area than polycrystalline cathode materials. It delivers an initial discharge capacity of 184 mAh/g at 0.1 C (18 mA/g) with a capacity retention of 91% after 100 cycles in the voltage window of 2.8–4.3 V.

Aqueous zinc-ion batteries (ZIBs) have shown great potential in large-scale energy storage systems due to their economic efficiency and environmental friendliness. However, cathodes for aqueous ZIBs are affected by the slow Zn[Formula: see text] diffusion kinetics and limited capacity. Herein, Mg[Formula: see text]V2O[Formula: see text]H2O (MgVO) nanobelt cathode with a large interlayer spacing of 13.0 Å is prepared via a one-step hydrothermal approach. Furthermore, the pre-intercalated Mg[Formula: see text] can stabilize the crystal structure and prevent Zn[Formula: see text] from being trapped in the lattice. As a result, MgVO cathode delivers a high capacity of 386 mAh g[Formula: see text] at 0.1 A g[Formula: see text], and impressive long-term cycling stability with a capacity retention of 91% after 1500 cycles at 5 A g[Formula: see text]. Moreover, the Zn/[Formula: see text]/MgVO battery can provide a high-energy density of 269 W h kg[Formula: see text] at 0.1 A g[Formula: see text] and a high-power density of 2701 W kg[Formula: see text] at 5 A g[Formula: see text]. The simple preparation and low cost make this cathode show great potential in the applications of large-scale energy storage.

In this work, we prepare Sn@NC (N-doped cotton-like carbon) materials using a fast method based on high-energy ball milling and subsequent heat treatments. The effects of milling time and heat treatment on the microstructural and electrochemical properties of the obtained powder are investigated. Compared with other electrodes, the sample milled for 90 min exhibited superior cycle stability, with a high capacity of 1207.9 mAh g[Formula: see text] over 100 cycles. In addition, at a current density of 500 mA g[Formula: see text], the electrode exhibited a capacity of 894.7 mAh g[Formula: see text] after 100 cycles.

The corrosion properties of AISI316L stainless steel (316 L SS) as bipolar plates are investigated under aqueous acid methanol solutions (0.05 M H2SO4 + 2 ppm HF + 10 M HCOOH + x M CH3OH (x = 0, 3, 6 and 9) solutions at 70 °C) to simulate the varied anodic operating conditions of direct formic acid fuel cells (DFAFCs). When the methanol content is higher, the potentiodynamic, potentiostatic polarisation and EIS tests of the 316 L SS bipolar plates all show excellent corrosion resistance. The surface morphology and the glow discharge mass spectrometer (GDMS) illustrate that the surface corrosion on 316 L SS bipolar plates is slowed down when the methanol concentration is increased. These results indicate the methanol plays the role in retarding the corrosion rate of the 316 L SS in simulated DFAFCs anodic operating conditions by restricting the proton conductivity in the test solutions. The sample tested in higher content methanol solution has smoother corroded surface and thinner passivation film, which contributes to a lower interfacial contact resistances (ICR) value.

Cu−0.5wt.%Cr alloy with high strength and high conductivity was processed by cryorolling (CR) and room temperature rolling (RTR), respectively. The microstructure, mechanical property and electrical conductivity of Cu−0.5Cr alloy after CR/RTR and aging treatment were investigated. The results indicate that obvious dislocation entanglement can be observed in matrix of CR alloy. The Cr particles in the alloy after CR and aging treatment possess finer particle size and exhibit dispersive distribution. The peak hardness of CR alloy is HV 167.4, significantly higher than that of RTR alloy. The optimum mechanical property of CR alloy is obtained after aging at 450 °C for 120 min. The conductivity of CR Cu−0.5Cr alloy reaches 92.5% IACS after aging at 450 °C for 120 min, which is slightly higher than that of RTR alloy.

Improving mechanical properties and maintaining shape precisions are both significant for the further developments of aluminum alloy profiles. A new kind of ECAP with rubber mandrels can be innovatively used to form these alloy profiles in recent years. The profiles can be maintained as their initial shapes after pressing through the channel. At the same time, their mechanical properties can be improved. In this paper, analytical method is firstly used to find the mechanical mechanism during this process. Both finite element simulation and physical experiment are used to verify these results obtained by the analytical model. Except for the head and tail parts of the profiles, the shape of middle parts can be maintained well. Based on the stress delivered, severe plastic deformation can be applied in forming process of complex profiles. Better mechanical properties and good shape precisions can be creatively realized in complex profiles at the same time.

A nitrogen expanded austenite (γN) layer with a thickness of 3 μm was prepared by plasma nitriding of 2205 duplex stainless steel (DSS) at 460°C for 1 h with hollow cathode discharge assistance. Th...