First-principles study of C3N nanoribbons as anode materials for Li-ion batteries

The potential of C₃N nanoribbons used as anode material for lithium-ion batteries has been systematically investigated through first-principles calculations. The results suggest that C₃N nanoribbons have excellent mechanical properties (stiffness ranging from 286.28 to 412.69 N m⁻¹) and good electronic conductivity (with a bandgap of 0-0.31 eV). Further studies reveal that the H-passivated C₃N nanoribbons have high Li insertion capacity (708.60 mA h g⁻¹) and significantly enhanced Li binding strength (0.21-2.11 eV) without the sacrifice of Li mobility. The high stiffness, superior cycle performance, good electronic conductivity, and excellent Li migration capability indicate the great potential of C₃N nanoribbons to be an anode material. The calculated results provide the valuable insights for the development of high-performance C₃N nanoribbons electrode materials in lithium-ion batteries.     

Si/polyaniline-based porous carbon composites with an enhanced electrochemical performance as anode materials for Li-ion batteries

Silicon/polyaniline-based porous carbon (Si/PANI-AC) composites have been prepared by a three-step method: coating polyaniline on Si particles using in situ polymerization, carbonizing, and further activating by steam. The morphology and structure of Si/PANI-AC composites have been characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectra, respectively. The content and pore structure of the carbon coating layer in Si/PANI-AC have been measured by thermogravimetric analysis and N₂ adsorption-desorption isotherm, respectively. The results indicate some micropores about 1~2 nm in the carbon layer appear during activation and that crystal structure and morphology of Si particles can be retained during preparation. Si/PANI-AC composites exhibit high discharge capacity about 1000 mAh g^?1 at 1.5 A g^?1; moreover, when the current density returns to 0.2 A g^?1, the discharge capacity is still 1692 mAh g^?1 and remains 1453 mAh g^?1 after 70 cycles. The results indicate that the porous carbon coating layer in composites plays an important role in the improvement of the electrochemical performance of pure Si.     

Li2MnSiO4/carbon nanofiber cathodes for Li-ion batteries

Pure single-phase Li₂MnSiO₄ nanoparticle-embedded carbon nanofibers have been prepared for the first time via a simple sol-gel and electrospinning technique. They exhibit an improved electrochemical performance over conventional carbon-coated Li₂MnSiO₄ nanoparticle electrodes, including a high discharge capacity of ～200 mAh g^?1, at a C/20 rate, with the retention of 77 % over 20 cycles and a 1.6-fold higher discharge capacity at a 1 C rate.     

Hierarchical hollow urchin-like structured MnO2 microsphere/carbon nanofiber composites as anode materials for Li-ion batteries

In this work, novel hollow urchin-like MnO₂ microspheres (u-MnO₂), consisting of a hollow core with nanotubes, are synthesized by a simple hydrothermal process. The morphology of the MnO₂ structures could be tuned from round particles to a hierarchical hollow urchin structure by controlling the hydrothermal reaction time, with no need for surfactant or templates. The nanostructures of the obtained u-MnO₂ are characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The X-ray diffraction (XRD) pattern of the u-MnO₂ reveals a tetragonal structure of α-MnO₂. The carbon nanofibers (CNFs) are uniformly deposited on u-MnO₂ to improve the electrical conductivity and to utilize the hierarchical architecture of u-MnO₂. As the anode electrode of Li-ion batteries, the u-MnO₂/CNFs nanocomposites exhibit discharge capacity of 988 mAh·g⁻¹ after 100 cycles with a good rate capability. The superior electrochemical performances of the u-MnO₂/CNFs nanocomposites can be attributed to the hierarchical urchin-like structures and the superior electrical conductivity of the nanocomposites, which can facilitate fast electron and ion transport and accommodate a large volume change during charge/discharge.     

Synthesis of nanosized Si composite anode material for Li-ion batteries

A simple method was proposed to prepare nanosized Si composite anode materials for lithium-ion (Li-ion) batteries. The preparation started with the shock-type ball milling of silicon in liquid media of polyacrylonitrile (PAN)/dimethylformamide (DMF) solution, forming slurry where the nano-Si particles were uniformly dispersed, followed by the drying of the slurry to remove DMF. The nanosized Si composite anode material was obtained after the pyrolysis of the mixture at 300 °C where the pyrolyzed PAN provided a conductive matrix to relieve the morphological change of Si during cycling. As-prepared composite presented good cyclability for lithium storage. The proposed process paves an effective way to prepare high performance Si, Sn, Sb and their alloys based composite anode materials for Li-ion batteries.     

Hard carbon derived from corn straw piths as anode materials for sodium ion batteries

Hard carbon is considered as the most promising anode material for practical sodium ion batteries. Herein, we report biomass-derived hard carbon made from corn straw piths through a simple carbonization process. X-ray diffraction patterns and Raman spectra elucidated highly disordered structures, and high-resolution transmission electron microscopy confirmed that the hard carbons have many local ordered structures containing turbostratic nanodomains and more nanovoids surround the turbostratic nanodomains. The electrochemical performances of the hard carbons were systematically investigated in sodium ion batteries. By optimizing the carbonization temperature, the sample carbonized at 1400 °C (HC1400) exhibited high reversible capacity of 310 mAh g^?1 and good cycling stability; the capacity can still retain 274 mAh g^?1 after 100 cycles. More importantly, HC1400 can deliver reversible capacity of 206 mAh g^?1 with 79% retention rate after 700 cycles measured at a current density of 200 mA g^?1, which is much better than those in most previous reports. This study provides a way to develop inexpensive, renewable, and recyclable materials from biomasses towards next-generation energy storage applications.     

Silicon/carbon nanocomposites used as anode materials for lithium-ion batteries

Silicon/carbon nanocomposites are prepared by dispersing nano-sized silicon in mesophase pitch and a subsequent pyrolysis process. In the nanocomposites, silicon nanoparticles are homogeneously distributed in the carbon networks derived from the mesophase pitch. The silicon/carbon nanocomposite delivers a high reversible capacity of 841 mAh g^?1 at the current density of 100 mA g^?1 at the first cycle, high capacity retention of 98 % over 30 cycles, and good rate performance. The superior electrochemical performance of nanocomposite is attributed to the carbon networks with turbostratic structure, which enhance the conductivity and alleviate the volume change of silicon.     

Theoretical prediction of honeycomb carbon as Li-ion batteries anode material

First principles calculations are performed to study the electronic properties and Li storage capability of honeycomb carbon. We find its right model consistent with the experimental result, the honeycomb carbon and its Li-intercalated configurations are all metallic which is beneficial to the electrode materials for lithium-ion batteries. The model 1 configuration shows fast Li diffusion and theoretical Li storage capacity of 319 mAh/g. Moreover, the average intercalation potentials for honeycomb carbon material is calculated to be low relatively. Our results suggest that the honeycomb carbon would be a new promising pure carbon anode material for Li-ion batteries.     

Template-free synthesis of hierarchical NiO microtubes as high performance anode materials for Li-ion batteries

Hierarchical nanostructured NiO (h-NiO) microtubes were prepared by a simple wet-chemical synthesis without the use of template or surfactant, followed by the calcination of α-Ni(OH)₂ precursor. The structural characterization of the h-NiO microtubes were performed by scanning microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), the results of which indicated that the obtained h-NiO microtubes are covered by the nanosheet grown perpendicularly on the tube surface. The unique hierarchical nanostructure of h-NiO microtubes with high surface area and many voids facilitates the electrochemical reaction as well as the short ion and electron transport pathway. Therefore, as anode electrode of Li-ion batteries, the h-NiO microtubes deliver largely enhanced cycle capacity of 770 mAh·g⁻¹ at a current density of 0.5 C after 200 cycles with high columbic efficiency, compared to the NiO rods. These results suggest that the h-NiO microtubes can be a promising anode material for Li-ion batteries.     

Hard carbons derived from pine nut shells as anode materials for Na-ion batteries

Hard carbons as promising anode materials for Na-ion batteries(NIBs) have captured extensive attention because of their low operation voltage, easy synthesis process, and competitive specific capacity. However, there are still several disadvantages, such as high cost and low initial coulombic efficiency, which limit their large-scale commercial applications.Herein, pine nut shells(PNSs), a low-cost biomass waste, are used as precursors to prepare hard carbon materials. Via a series of washing and heat treatment procedures, a pine nut shell hard carbon(PNSHC)-1400 sample has been obtained and delivers a reversible capacity of around 300 mAh/g, a high initial coulombic efficiency of 84%, and good cycling performance. These excellent Na storage properties indicate that PNSHC is one of the most promising candidates of hard carbon anodes for NIBs.     

Graphene-Co/CoO shaddock peel-derived carbon foam hybrid as anode materials for lithium-ion batteries

A novel graphene (G)-Co/CoO shaddock peel-derived carbon foam (SPDCF) hybrid was fabricated as anode materials for lithium-ion batteries. The preparation of G-Co/CoO SPDCF was according to the following two steps. Firstly, the dried shaddock peels were immersed into the mixture of Co(NO₃)₂/graphene oxide for about 12 h. Then, the shaddock peels were taken out and heated at 800 °C for 2 h under N₂ atmosphere. The strategy is simple, low-cost, and environmentally friendly because the shaddock peel is abundant and renewable. The obtained G-Co/CoO SPDCF hybrid were carefully characterized by SEM, EDS, XPS, XRD, TGA, BET, TEM, and electrochemical techniques. The results showed that the carbonized shaddock peels had hierarchical porous nanoflakes structures and graphene was uniformly dispersed into the SPDCF. The nanosized Co/CoO was formed on the G-SPDCF. The resulted G-Co/CoO SPDCF hybrid could maintain a high capacity of 600 mA h g^?1 at 0.2 A g^?1 after 80 cycles, which was much higher than that of commercial graphite (372 mA h g^?1). The enhanced performance might be ascribed to the existence of lots of uniform Co/CoO and the hierarchical G-SPDCF alleviating the mechanical stress during the process of lithiation/delithiation.     

Two-dimensional MnN utilized as high-capacity anode for Li-ion batteries

When developing high performance lithium-ion batteries,high capacity is one of the key indicators.In the last decade,the progress of two-dimensional(2 D) materials has provided new opportunities for boosting the storage capacity.Here,based on first-principles calculation method,we predict that MnN monolayer,a recently proposed 2 D nodal-loop halfmetal containing the metallic element Mn,can be used as a super high-capacity lithium-ion batteries anode.Its theoretical capacity is above 1554 mA-h/g,more than four times that of graphite.Meanwhile,it also satisfies other requirements for a good anode material.Specifically,we demonstrate that MnN is mechanically,dynamically,and thermodynamically stable.The configurations before and after lithium adsorption exhibit good electrical conductivity.The study of Li diffusion on its surface reveals a very low diffusion barrier(～ 0.12 eV),indicating excellent rate performance.The calculated average open-circuit voltage of the corresponding half-cell at full charge is also very low(～0.22 V),which facilitates higher operating voltage.In addition,the lattice changes of the material during lithium intercalation are very small(～ 1.2%-～4.8%),which implies good cycling performance.These results suggest that 2 D MnN can be a very promising anode material for lithium-ion batteries.     

One-pot facile synthesis of CuS/graphene composite as anode materials for lithium ion batteries

CuS/graphene composite has been synthesized by the one-pot hydrothermal method using thiourea as the sulfur source and reducing agent. The formation of CuS nanoparticles and the reduction of graphene oxide occur simultaneously during the hydrothermal process, which enables a uniform dispersion of CuS nanoparticles on the graphene nanosheets. The electrochemical performance of CuS/graphene composite was studied as anode materials for lithium ion batteries. The obtained CuS/graphene composite exhibits a relative high reversible capacity and good cycling stability. The good electrochemical performance of CuS/graphene composite can be attributed to graphene, which improves the electronic conductivity of composite and enhances the interfacial stability of electrode and electrolyte.     

In situ synthesis of a CoSb3/nano-carbon-web anode for Li-ion batteries

A CoSb₃/nano-carbon-web composite was synthesized by an in situ method using polypropylene as both the reductive agent and carbon source. Hydrogen and carbon from the pyrolysis of polypropylene provide a strong reductive atmosphere and ensure the reduction of Co²⁺ (and Sb³⁺) to form CoSb₃, and the residual carbon would in situ wrap around the freshly crystallized CoSb₃. Electrochemical measurements show that CoSb₃/nano-carbon-web as Li-ion battery anode reaches an initial charge capacity of 770 mA hg^?1 and remains above 430 mA hg^?1 after 20 cycles. The in situ synthesis route has the potential as a general method for the preparation of other metal (or alloy)/nano-carbon-web composites.     

Pyrolytic carbon derived from coffee shells as anode materials for lithium batteries

Disordered carbonaceous materials have been obtained by pyrolysis of coffee shells at 800 and 900 °C with pore-forming substances such as KOH and ZnCl₂. X-ray diffraction studies revealed a carbon structure with a large number of disorganized single layer carbon sheets. The structure and morphology of the materials have been greatly varied upon the addition of porogens. The prepared carbon materials have been subjected to cycling studies. The KOH-treated products offered higher capacity with improved stability than those with untreated and ZnCl₂-treated one.     

Disodium terephthalate/multiwall-carbon nanotube nanocomposite as advanced anode material for Li-ion batteries

Organic small molecule materials have attracted extensive attention due to their environmentally friendly, sustainability, and low cost which can be obtained from biomass and recyclable resources for Li/Na-ion batteries. However, the intrinsic poor electronic conductivities and the dissolution in organic liquid electrolyte lead to poor electrochemical performance, thus preventing them from practical application. To tackle these issues, herein, we take disodium terephthalate (Na₂TP) as an example and report an organic/multiwall-carbon nanotube nanocomposite via a simple spray drying methodology as an anode material for Li-ion battery. It delivers improved electrochemical performance compared to the pristine Na₂TP microspheres produced by the same spray drying method and the bulk microsized Na₂TP prepared by a conventional water-crystallization method. This is mainly due to the as-prepared nanocomposite can shorten the Li-ion diffusion distance, form highly conductive network and slow the dissolution rate. Our simple methodology could be of interest designing newly organic composites.     

Chemically shortened multi-walled carbon nanotubes used as anode materials for lithium-ion batteries

An easy chemically cutting process, modified Hummers' method, was proposed to treat multi-walled carbon nanotubes, successfully cutting pristine long, entangled carbon nanotubes into hydrosoluble pieces, mostly less than 200 nm. This short, chemically oxidized carbon nanotube was then applied as an anode material for lithium-ion batteries. The as-prepared material possessed higher reversible capacity and coulombic efficiency. The intrinsic factors were explored by X-ray photoelectron spectroscopy and cyclic voltammetry.     

Evaluation of structural and electrochemical properties of the MnSb–Li system as anode for Li-ion batteries

The electrochemical reaction mechanisms between lithium and cystalline MnSb are investigated by X-ray diffraction, ¹²¹Sb Mössbauer spectroscopy, and X-ray absorption spectroscopy (XAS). The analysis of the experimental data at different depths of the electrochemical discharge process reveals a complex reaction mechanism comprising two steps. The main reaction of the first step corresponds to the dispersion of lithium in the MnSb matrix with formation of the intermediate compound LiMnSb. The second step corresponds to a Li–Sb alloying process with formation of Li₃Sb.     

Development and characterization of a novel silicon-based glassy composite as an anode material for Li-ion batteries

A novel silicon-based glassy composite anode material with high initial coulombic efficiency and long cycling performance for lithium-ion batteries was synthesized by a wet mechanochemical reduction method. The in situ formed Si particles with size of 5-10 nm were uniformly distributed in the glassy matrices formed by B₂O₃ and P₂O₅. The as-prepared composite electrode revealed an initial charge and discharge capacity of 432.7 and 514.4 mAh g^− 1, respectively, with an initial coulombic efficiency of 84%. After 100 cycles, the reversible capacity retention rate was still up to 97%, meaning a favorable cycling stability.