Nitrogen/sulfur co-doped disordered porous biocarbon as high performance anode materials of lithium/sodium ion batteries

Nitrogen/sulfur co-doped disordered porous biocarbon was facilely synthesized and applied as anode materials for lithium/sodium ion batteries. Benefiting from high nitrogen (3.38 wt%) and sulfur (9.75 wt%) doping, NS_1-1 as anode materials showed a high reversible capacity of 1010.4 mA h g⁻¹ at 0.1 A g⁻¹ in lithium ion batteries. In addition, it also exhibited excellent cycling stability, which can maintain at 412 mAh g^-1 after 1000 cycles at 5 A g⁻¹. As anode materials of sodium ion batteries, NS_1-1 can still reach 745.2 mA h g⁻¹ at 100 mAg^-1 after 100 cycles. At a high current density (5 A g^-1), the reversible capacity is 272.5 mA h g⁻¹ after 1000 cycles, which exhibits excellent electrochemical performance and cycle stability. The preeminent electrochemical performance can be attributed to three effects: (1) the high level of sulfur and nitrogen; (2) the synergic effect of dual-doping heteroatoms; (3) the large quantity of edge defects and abundant micropores and mesopores, providing extra Li/Na storage regions. This disordered porous biocarbon co-doped with nitrogen/sulfur exhibits unique features, which is very suitable for anode materials of lithium/sodium ion batteries.     

ZnSe/CoSe/NCDPH composites as anode materials for lithium ion batteries with high capacity and long cycle

In this paper, dopamine hydrochloride (DPH) is introduced to synthesize ZIF-8@ZIF-67@DPH in the preparation of ZIF-8@ZIF-67. ZnSe/CoSe/NC_DPH (N-doped carbon) composites are calcined in a high-temperature inert atmosphere with ZIF-8@ZIF-67@DPH as the precursor, selenium powder as the selenium source. ZnSe/CoSe/NC_DPH has high discharge specific capacity, good cycle stability and outstanding rate performance. The first discharge capacity of ZnSe/CoSe/NC_DPH is 1616.6 mAh g⁻¹ at the current density of 0.1 A g⁻¹, and the reversible capacity remains at 1214.2 mAh g⁻¹ after 100 cycles, the reversible capacity is 416.7 mAh g⁻¹ after 1000 cycles at 1 A g⁻¹. Therefore, ZnSe/CoSe/NC_DPH composites provide a new step for the research and synthesis of new stable, high-capacity, and safe high-performance lithium ion batteries. The bimetallic selenide composites not only have bimetallic active sites, but also can form synergistic effect between different metal phases, which can effectively reduce the capacity attenuation caused by volume expansion and reactive stress enrichment during lithium storage of metal oxide anode materials. Meanwhile, N-doped carbon can improve the conductivity and provide more active sites to store lithium, thus improving its lithium storage capacity.     

Bio-enzymatic synthesis of nitrogen-doped porous carbon/SnO2/carbon microspheres as high-performance composite materials for lithium-ion and sodium-ion batteries

In this study, a nitrogen-doped 3D porous starch-derived carbon/SnO₂/carbon (PSC/SnO₂/C) composite is synthesized with porous starch as a carbon source by biological enzymatic hydrolysis. Compared with the traditional complex acid-base reagent method, the biological enzymatic method is more environmentally friendly and economical, and it can also naturally introduce nitrogen sources and dope the carbon layer. Many mesoporous nanostructures provide enough buffer space and promote the ions' and electrons’ transmission rate. The formation of the Sn–O–C bond between SnO₂ and carbon ensures the stability of the structure. As a result, the PSC/SnO₂/C composite exhibits a high initial discharge capacity (1802 mAhg⁻¹ at 0.2 A g⁻¹ for LIBs and 549 mAh g⁻¹ at 0.1 A g⁻¹ for SIBs) and good cycle stability (701 mAh g⁻¹ at 0.2 A g⁻¹ after 100 cycles for LIBs and 271 mAh g⁻¹ at 0.1 A g⁻¹ after 100 cycles for SIBs). This synthesis method can prepare other energy storage systems such as fuel cells, supercapacitors, and metal ion batteries.     

Micro-nano Cu2Se as a stable and ultralong cycle life anode material for sodium-ion batteries

Transition metal selenides have received great attention as promising anode materials for sodium-ion batteries (SIBs). However, it still faces the change of volume and structure, which reduces the rate performance and cycle stability in cycle process. The design of micro-nano hierarchical structure is an important method to improve the structural stability and reaction kinetics in discharge-charge process. In this study, the micro-nano Cu₂Se is synthesized using a simple solvothermal and annealing treatment method, and it shows excellent electrochemical performance as anode material for SIBs. It exhibits excellent rate capacity (373.8 mAh g^?1 at 0.1 A g^?1 and 303.48 mAh g^?1 when the current density is increased to 10 A g^?1) and cycling stability (250.3 mAh g^?1 after 4000 cycles at 5 A g^?1, achieving 85.80% for retention rate). In addition, the deep reaction mechanism of Cu₂Se has been explored through ex situ XRD and HRTEM.     

Porphyrin-based conjugated microporous polymers with dual active sites as anode materials for lithium-organic batteries

Conjugated microporous polymers have been regarded as ideal electrode materials for green lithium-ion batteries (LIBs) considering their advantages such as insolubility, adjustable structure and porosity. Herein, we synthesize porphyrin-based CMPs (Co-PCMPs) with dual active sites composed of metal-N4 conjugated macrocycle and conjugated carbonyl groups through the condensation polymerization. In view of the rational design and unique organic skeleton, when used as the anode material for LIBs, Co-PCMPs show a high capacity (700 mAh g^?1 at 0.05 A g^?1) and excellent rate capability (400 mAh g^?1 at 1.0 A g^?1). Meanwhile, theoretical calculations are used to further study the lithium storage mechanism of Co-PCMPs as the anode material for LIBs. In addition, a full cell is also assembled by using LiCoO₂ as the cathode material and Co-PCMPs as the anode material, which also shows a high capacity (212 mAh g^?1 at 0.05 A g^?1) and good rate capability (116 mAh g^?1 at 0.2 A g^?1), implying the possibility of practical applications of this type of conjugated microporous polymers.     

New strategy to prepare nitrogen self-doped graphene nanosheets by magnesiothermic reduction and its application in lithium ion batteries

Nitrogen self-doped graphene (N/G) nanosheets were prepared through magnesiothermic reduction of melamine. The obtained N/G features porous structure consisting of multi-layer nanosheets. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectra and X-ray diffraction (XRD). As anode of lithium ion batteries (LIBs), it exhibits excellent reversible specific capacity of 1753 mAh g⁻¹ at 0.1 A g^-1 after 200 cycles. The reversible capacity can maintain at 1322 mAh g⁻¹ after 500 cycles at 2 A g⁻¹. At the same time, all results indicate remarkable cycle stability and rate performance as anode materials. Furthermore, this study demonstrates an economical, clean and facile strategy to synthesize N/G nanosheets from cheap chemicals with excellent electrochemical performance in LIBs.     

Fabrication of CoFe/N-doped mesoporous carbon hybrids from Prussian blue analogous as high performance cathodes for lithium-sulfur batteries

CoFe/N-doped mesoporous carbon hybrids are synthesized by a simple pyrolysis of Prussian blue analogue (PBA) and melamine, in which the structure is rationally designed by controlling the weight ratio of PBA/melamine and annealing temperature. By applying the composite as the cathode material for lithium-sulfur batteries, it demonstrates outstanding electrochemical performances including a high reversible capacity (1315 mAh g⁻¹ at 0.2 C), excellent rate capability (724 and 496 mAh g⁻¹ at 2 and 5 C rates, respectively) and superior cycling stability (528 and 367 mAh g⁻¹ at 2 and 5C after 500 cycles, respectively). The synergetic effect of the mesoporous carbon matrix, uniform sized CoFe nanoparticles and N heteroatoms simultaneously contributes to the confinement of sulfur species. The presence of abundant mesopores and micropores can physically confine sulfur species. The formed CoFe-N_x moieties can not only improve the electronic conductivity of the as-prepared composites, but also offer highly effective active sites for chemical absorption and catalytic transformation of polysulfides to suppress any shuttle effect. In addition, the mesoporous structure can effectively alleviate the volume changes resulted from charge–discharge process. The strategy developed in this work proposes an alternative way to obtain N-doped mesoporous carbon matrix modified with CoFe nanoparticles for high performance cathode materials of lithium-sulfur batteries.     

Wet-chemistry synthesis of Li4Ti5O12 as anode materials rendering high-rate Li-ion storage

Compared with traditional anode materials, spinel-structured Li₄Ti₅O₁₂ (LTO) with “zero-strain” characteristic offers better cycling stability. In this work, by a wet-chemistry synthesis method, LTO anode materials have been successfully synthesized by using CH₃COOLi·2H₂O and C₁₆H₃₆O₄Ti as raw materials. The results show that sintering conditions significantly affect purity, uniformity of particle sizes, and electrochemical properties of as-prepared LTO materials. The optimized LTO product calcined at 650°C for 20 hours demonstrates small particle sizes and excellent electrochemical performances. It delivers an initial discharge capacity of 242.3 mAh g⁻¹ and remains at 117.4 mAh g⁻¹ over 500 cycles at the current density of 60 mA g⁻¹ in the voltage range of 1.0 to 3.0 V. When current density is increased to 1200 mA g⁻¹, its discharge capacity reaches 115.6 mAh g⁻¹ at the first cycle and remains at 64.6 mAh g⁻¹ after 2500 cycles. The excellent electrochemical performances of LTO can be attributed to the introduction of rutile TiO₂ phase and small particle sizes, which increases electrical conductivity and electrode kinetics of LTO. Therefore, as-synthesized LTO in this study can be regarded as a promising anode candidate material for lithium-ion batteries.     

Well-dispersed Sb2O3 nanoparticles encapsulated in multi-channel-carbon nanofibers as high-performance anode materials for Li/dual-ion batteries

Reasonable design and construction of electrode materials with high-performance and low-cost are essential for Li-ion batteries (LIBs) and dual-ion batteries (DIBs). Herein, an eco-friendly and facile strategy is proposed to encapsulate Sb₂O₃ nanoparticles in one-dimensional (1D) multi-nanochannel-containing carbon nanofibers (Sb₂O₃@MCNF) using the electrospinning method as well as the subsequent calcination. Such unique construction not only effectively reduces the large volume variation during cycling, but also achieves the fast Li⁺/e^? transportation. As a result, the optimized sample with the precursor triphenylantimony (III) content of 0.35 g (Sb₂O₃@MCNF-0.35) exhibits superior electrochemical performance as anode materials for LIBs and Li-based DIBs (LDIBs), including high reversible capacity (~333.5 mAh g^?1 at 1 A g^?1 for LIBs and 233.5 mAh g^?1 at 0.2 A g^?1 for LDIBs) and favorable cycling stability (over 800 cycles for LIBs and 100 cycles for LDIBs). These results demonstrate that the well-designed Sb₂O₃@MCNF-0.35 can availably boost the electrochemical performance, which provides vast potential for applications in the field of high-performance energy storage equipment.     

Multiporous core-shell structured MnO@N-Doped carbon towards high-performance lithium-ion batteries

It is imminently to seek for high energy density in addition to a sensational lifetime of lithium-ion batteries (LIBs) to meet growing requisition in the energy storage application. Anode containing metal oxide composite is being thoroughly investigated for their higher capacity than that of the commercial graphite. A multiporous core-shell structured metal oxide composite anode possessing the excellent capacity and superb lifespan for LIBs is designed. In detail, metal oxide (i.e., MnO) is encapsulated in N-doped carbon shell (MnO@N–C) via coprecipitation-annealing technique. During annealing, abundant void space among MnO cores/between MnO cores and N–C shells is obtained. This space can efficaciously buffer volume changes of MnO upon cycles. Benefiting from the unique structure and heteroatom doping, the capacity of MnO@N–C microcube anode exhibits 576 mAh g⁻¹ at 5 A g⁻¹ with an ultra-long lifespan more than 3500 cycles. The connection between the electrode characteristics and structure is concurrently examined by adopting kinetic analysis. Finally, a full lithium-ion battery is presented, applying the MnO@N–C (anode) and Nick-rich layered oxide (cathode). It is believed that structural designing with heteroatom doping can be utilized in vaster fields for superior capabilities.     

Uniform carbon coating drastically enhances the electrochemical performance of a Fe3O4 electrode for alkaline nickel–iron rechargeable batteries

Fe₃O₄@C composites for use in alkaline nickel-iron rechargeable batteries are synthesized via a spray drying method. SEM and TEM confirm that the Fe₃O₄@C composite is a secondary particle microsphere formed by many primary particles uniformly coated with carbon. The particles aggregate with each other, which is equivalent to forming a three-dimensional conductive mesh. The electrochemical properties of the bare Fe₃O₄ and Fe₃O₄@C composites as anode materials for alkaline nickel-iron batteries are investigated. The results show that the Fe₃O₄@C composite synthesized by spray drying exhibits considerably high discharge capacities and an excellent rate capability. The specific discharge capacity of the Fe₃O₄@C composite reaches 693.7 mAh g⁻¹ at a current density of 300 mA g⁻¹, with a charging efficiency of 92.5%. Moreover, the Fe₃O₄@C composite exhibits an admirable cycling stability with a superior capacity retention of 92.0% for 100 cycles at a current density of 300 mA g⁻¹. In addition, discharge capacities of 556.7 and 420.1 mAh g⁻¹ are achieved at high current densities of 1200 and 2400 mA g⁻¹, respectively.     

Aligned nickel–cobalt oxide nanosheet arrays for lithium ion battery applications

Aligned nickel–cobalt nanosheet arrays are deposited on nickel foam substrates by means of chemical bath deposition technique. The nanosheet arrays are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The electrochemical performances as anode materials of lithium ion batteries are investigated by galvanostatic charge–discharge cycle and cyclic voltammetry (CV) tests. The results show that the nickel–cobalt oxide film prepared from the solution in which Ni/Co = 3/1 has the best performance. Its initial charge capacity at 0.1 A g⁻¹ is 798 mAh g⁻¹. When cycled at higher current densities of 0.5 and 1.0 A g⁻¹, the initial charge capacities are 570 and 500 mAh g⁻¹, and 84% and 86% can be retained after 50 cycles, respectively. It is believed that the interconnected nanosheet-array structure and the nickel–cobalt binary composition play important roles in their electrochemical performances.     

Low temperature synthesis of flower-like ZnMn2O4 superstructures with enhanced electrochemical lithium storage

In this communication, flower-like tetragonal ZnMn₂O₄ superstructures are synthesized by a facile low temperature solvothermal process. Characterizations show that these ZnMn₂O₄ superstructures are well crystallized and of high purity. The product exhibits an initial electrochemical capacity of 763 mAh g⁻¹ and retains stable capacity of 626 mAh g⁻¹ after 50 cycles. Its stable capacity is significantly higher than that of nanocrystalline ZnMn₂O₄ synthesized by a polymer-pyrolysis method. It is found that the higher capacity retention can be attributed to three-dimensional superstructural nature of the as-prepared flower-like ZnMn₂O₄ material. This study suggests that the solvothermally synthesized flower-like ZnMn₂O₄ is a promising anode material for lithium-ion batteries.     

A layered porous Ni structure contributes to superior low-temperature performance of hydrogen storage alloys

The poor low-temperature performance of negative electrode materials— hydrogen storage alloys (HSAs) has impeded applications of nickel metal hydride batteries in new energy vehicles. Here, we propose a simple and effective strategy to improve low-temperature properties of the commercial HSA with HCl etching and heat treatment. The layered porous Ni surface structure formed during this process improves the electrochemical reaction kinetics, and thus results in a larger discharge capacity of 102.63 mAh g⁻¹ at 233 K compared with those of bare (11.52 mAh g⁻¹) and acid-corroded (43.00 mAh g⁻¹) alloys. This method could be extended to enhance the low-temperature performance of other HSA systems.     

Amorphous ATO and amorphous ATO based composite anodes for Li-ion batteries

In this study, amorphous antimony doped tin oxide (ATO) coatings on Cr coated stainless steel and multiwall carbon nanotube (MWCNT) buckypaper substrates were prepared using a radio frequency (RF) magnetron sputtering process as anode materials in lithium-ion batteries. The MWCNT anode, amorphous SnO₂:Sb anode and amorphous SnO₂:Sb-MWCNT nanocomposite anode have shown first discharge capacities of 446 mA h g⁻¹, 1064 mA h g⁻¹ and 1462 mA h g⁻¹, respectively. The best cycling performance were observed for amorphous SnO₂:Sb-MWCNT nanocomposite anode.     

Facile synthesis of mesoporous TiNb2O7/C microspheres as long-life and high-power anodes for lithium-ion batteries

The unique ReO₃ crystallographic shear structure of TiNb₂O₇ has enabled its application as anode material for lithium-ion batteries, in which the lattice parameter and volume change of TiNb₂O₇ are often negligible during lithium-ion insertion/extraction. However, several intrinsic problems of TiNb₂O₇, including low electronic and ionic conductivity, can restrict its application significantly. In this study, carbon-coated mesoporous TiNb₂O₇ microspheres are fabricated through a simple solvothermal reaction. By combining the advantages of both the amorphous carbon and mesoporous structure, TiNb₂O₇/C composite exhibits superior lithium storage performance, with higher rate capability (200 mAh g⁻¹ at 30 C) and cyclability (191 mAh g⁻¹ at 10 C after 500 cycles). The improved performance is due mainly to the high pseudocapacitance and low charge transfer resistance obtained from the mesoporous structure and amorphous carbon layer. The study provides a new way of constructing TiNb₂O₇ for ultra-fast storage devices, demonstrating great potential for application in power batteries.     

Facile controlled synthesis of coral-like nanostructured Sb2O3@Sb anode materials for high performance sodium-ion batteries

Sb₂O₃@Sb composites consisting of a coral-like nano-Sb skeleton with surface decorated Sb₂O₃ nanoparticles were synthesized and evaluated as sodium-ion battery anodes. The facile synthesis route involves etching of elemental Al from a Sb₅Al₉₅ alloy to obtain the coral-like nano-Sb, which was then subjected to mild oxidization in air to introduce Sb₂O₃. The optimal elemental and phase composition was achieved by tuning and controlling the preparation parameters. The Sb₂O₃ on the surface synergistically reduces anode volume changes to stabilize the composite structure whilst significantly accelerates the electrochemical kinetics. The three-dimensional network in Sb₂O₃@Sb composite also possesses a uniform porous structure that effectively relieves the volume changes and provides fast Na⁺ transportation channels. The best Sb₂O₃@Sb composite from this study shows the significantly improved specific capacity of 724.3 mAh g⁻¹ at 1000 mA g⁻¹ current density, with 526.2 mAh g⁻¹ of specific capacity remained after 150 charge-discharge cycles. A high specific capacity of 497.3 mAh g⁻¹ was achieved at 3000 mA g⁻¹, which to our knowledge performs the best among most Sb-based anodes reported in the literature. This on top of its facile synthesis makes the Sb₂O₃@Sb composite a viable anode candidate for future sodium-ion batteries.     

Electrochemically converting Sb2S3/CNTs to Sb/CNTs composite anodes for sodium-ion batteries

Facile synthesis methods and rich-reserve feedstocks are the keys to accelerating the scale commercial use of Sb-based anodes for sodium-ion batteries (SIBs). In this paper, we synthesize Sb/carbon nanotubes (CNTs) composite anodes by a straightforward electrochemical approach using stibnite and CNTs as feedstocks. The concentrated sodium hydrate solution profits the formation of antimony and electrons enables the solid-state electrochemical desulfurization. The low-cost stibnite can be directly obtained from the earth's crust avoiding the intermediate processes and pollution of preparing the common-used raw materials SbCl₃ and metallic Sb. CNTs provides a network for both electron and ion transport, thereby resulting in producing Sb particles anchored in the CNTs network as well as restraining the cluster of electrolytic Sb particles. The electrolytic Sb-0.5CNTs anode delivers a decent capacity of 510 mAh g^?1 at 0.1 A g^?1 after 200 cycles and even 425 mAh g^?1 at 1 A g^?1 over 100 cycles. The excellent sodium-storage performances are attributed to the unique structure of the electrolytic Sb/CNTs composite. This electrochemical desulfurization method can be expanded to prepare other metal-carbon type anodes from metal sulfides ores and carbon materials composites.     

Microstructure controlled ZnCo2O4/C microhydrangea nanocomposites as highly reliable anodes for lithium-ion batteries

ZnCo₂O₄/C microhydrangeas with controllable microstructure are successfully synthesized through a simple citrate-guided solvothermal method and following thermal decomposition. The experimental results reveal that the citrate-directed self-regulation of Zn-Co-EG agglomerates play a critical role in the formation of the hydrangea-like precursors. When applied as anode material in lithium ion batteries (LIBs), ZnCo₂O₄/C microhydrangeas exhibited high available capacities of 964.6 mAh g⁻¹ at 1 A g⁻¹ after 200 cycles and 704.4 mAh g⁻¹ at 4 A g⁻¹ over 1000 cycles. The excellent reliability is attributed to the superior microstructure that provides many benefits including enhanced electron or ion transport and improved structure stability, etc.     

In-situ synthesis of two-dimensional sheet-like MoO2/NPC@rGO as advanced anode for alkali metal ion batteries

MoO₂ anode displays excellent potential in the alkali ion batteries owing to its large capacity, high conductivity and stability. However, exploiting the stable and high performance MoO₂ anode endowed with triple roles for the storage of lithium/sodium/potassium ions is still a challenge. Herein, a two-dimensional sheet-like MoO₂/NPC@rGO composites were in-situ synthesized and utilized as anode materials for alkali metal ion batteries. Applied as an anode in lithium ion batteries (LIBs), superior cycling capability and rate performance were obtained, which kept a large reversible capacity of 1233.1 mAh/g in the 200th cycle at 100 mA/g. Impressively, it displayed superior long cycling performance over 1000 cycles with a 249.5 mAh/g capacity at a high current density of 10 A/g. Simultaneously, MoO₂/NPC@rGO displayed enhanced electrochemical performance both in sodium and potassium ion batteries (NIBs/KIBs). Furthermore, the ex-situ X-ray photoelectron spectroscopy results verified the reversible reaction during Li⁺ insertion-extraction process. The improved energy storage properties were attributed to the typical two dimensional structure and synergistic effects between various constituents, which suppressed the volume change, created more active sites, increased the conductivity and facilitated reaction kinetics. More significantly, our design provides a simple and green route to synthesize transition metal oxide anode and promote their applications in energy storage devices.