High-performance Anode Material For Li-ion Batteries Research Articles

Highly conductive and robust telluride-carbon hybrid matrix for enhanced copper diphosphide anode in Li-ion batteries

CuP2 is a phosphorous-rich transition metal phosphide that can be a potential anode for Li-ion batteries (LIBs) because of its high theoretical capacity (∼1280 mA h g−1) and intrinsic alleviation of volume change owing to the presence of inactive Cu. Despite these advantages, the electrochemical performance of CuP2 is not satisfactory owing to its low electrical conductivity and insufficient regulation of large volume expansion during cycling. Herein, we propose a CuP2-Te-C ternary composite as a high-performance anode material for LIBs. The presence of Te-C can circumvent the limitations of CuP2, as it can synergistically increase the electrical conductivity while mitigating the cycling instability. The individual roles of Te and C in enhancing the active CuP2 performance were studied using various morphological and electrochemical characterizations. Furthermore, an appropriate C content (25 wt%) that can increase the specific capacity while maintaining cycling stability was determined. Under these conditions, CuP2-Te-C(25 %) displayed a good cycling performance (532 mA h g−1 at 100 mA g−1 after 100 cycles) and rate capability (501 mA h g−1 at 3.0 A g−1). The superior performance of CuP2-Te-C(25 %) studied comprehensively using electrochemical impedance spectroscopy revealed a higher diffusivity and lower charge transfer resistance for CuP2-Te-C(25 %) than its counterparts. This study presents new perspectives on high-performance metal-phosphide anode materials for LIBs.

Two-Dimensional α-SiX (X = N, P) Monolayers as Efficient Anode Material for Li-Ion Batteries: A First-Principles Study

Density functional theory simulations were performed to investigate the structural, electronic, and electrochemical properties of the two-dimensional α-SiX (X = N, P) monolayers as anode material in Li-ion batteries (LIBs). Our result indicates that α-SiX monolayers have excellent mechanical, dynamical, and thermal stability. The obtained adsorption energy values suggest that the Li atom adsorption over α-SiX is a favorable process. According to the Löwdin charge transfer and partial density of states analysis, charge transfer takes place from Li atom to α-SiX monolayers. From the band structure plots, we observed that after the adsorption of a single Li atom, the α-SiX monolayers are converted into a metallic state from the semiconductor state and remain in the metallic state for the different adsorption concentrations of Li atoms, which is essential to facilitate the diffusion of stored electrons. The calculated specific storage capacity is 956.16 and 733.66 mA h g–1 for α-SiN and α-SiP monolayers, respectively, which is remarkably higher than that of the conventional anode materials (such as graphite and TiO2). Ab initio molecular dynamics simulations confirm the room-temperature stability of the α-SiX monolayers at the maximum loading of Li atoms. The lower diffusion energy barriers of 0.30 eV (for α-SiN monolayers) and 0.16 eV (for α-SiP monolayers) ensure good diffusivity of ions over monolayers. The calculated open-circuit voltage is also favorable for battery applications. The aforementioned findings suggest that the α-SiX monolayers could be beneficial and compelling host anode material for high-performance LIBs.

Constructing ZnCo2O4@CTP microspheres as a high-energy lithium storage material

Transition metal oxides are deemed as a promising substitute for graphite anode materials of Li-ion batteries (LIBs) on account of their large specific capacity. Nonetheless, the large volume change in the process of charging and discharging leads to low capacity retention. Herein, a well-designed ZnCo2O4@coal tar pitch based porous carbon (ZCO-CTP) microsphere is prepared to construct the high-performance anode of LIBs. The coating modification of CTP significantly reduces the polarization and charge transfer resistance and improves the migration ability of ions and electrons, thus achieving a superior reversible capacity and cycling stability of ZCO-CTP anode. The battery with obtained ZCO-CTP5 provides a large charge capacity of 406.17 mAh/g at 1000 mA g−1 compared with pristine ZCO (only 157.78 mAh/g). Even after 1000 cycles at 1000 mA g−1, the battery can achieve a charge/discharge capacity of 598.46/601.17 mAh/g. We believe that the application of CTP will provide a new perspective for the exploitation of high-performance anode materials for LIBs.

Well-dispersed tin nanoparticles encapsulated in amorphous carbon tubes as high-performance anode for lithium ion batteries

Tin/carbon (Sn/C) nanocomposite is considered as a promising anode material for high-performance Li-ion batteries (LIBs). However, since the carbon matrix is always derived from high-temperature carbonization of polymers and Sn has a low melting point (232 °C), the Sn nanoparticles in the Sn/C tend to be heavily aggregated during the carbonization process. It is thus challenging to synthesize well-dispersed Sn nanoparticles in a carbon matrix. Here, we report a facile templating method to encapsulate uniform well-dispersed Sn nanoparticles in amorphous carbon tube (Sn@aCT). The electrode fabricated with the hierarchical Sn@aCT exhibits excellent cycle performance. A stable specific capacity of 870 mAh g−1 after 350 cycles and a Li-ion diffusion coefficient as high as are obtained. Meanwhile, the intermediate structure of SnO2@aCT and a carbon-coated Sn yolk-shell nanostructure (Sn@C-YS) are investigated for comparison. The results further manifest the advantage of the architecture of the Sn@aCT. Our strategy provides a feasible way to optimize Sn/C nanocomposite as a high-performance anode material for LIBs.

C3N/blue phosphorene heterostructure as a high rate-capacity and stable anode material for lithium ion batteries: Insight from first principles calculations

Two dimensional heterostructures could not only combine each other’s advantages, but also compensate for their drawbacks. In this work, we systematically investigated the C3N/blue phosphorene (C3N/BlueP) heterostructure as an anode material for Li-ion batteries (LIBs) based on the comprehensive first principles computations. Our results show that the C3N/BlueP heterostructure possesses good structural stability and ultra-high stiffness (Yx = 417.3 N/m). The band gap of C3N/BlueP heterostructure is 0.026 eV, exhibiting good electrical conductivity for fast electron transport. Attributed to the synergistic effect, the adsorption energy of Li in the interface region of C3N/BlueP heterostructure (−2.057 to −1.898 eV) is greatly increased in comparison with pristine C3N (−0.563 eV) and BlueP (−1.852 eV). Consequently, the specific capacity is up to 1092 mA h/g, which far exceeds those of other BlueP-based heterostructures and commercial graphite (372 mA h/g). Additionally, the diffusion barrier for the C3N/BlueP heterostructure is only 0.12 eV, implying fast Li migration. Given these exceptional properties, that is, good electrical conductivity, ultra-high stiffness, high specific capacity and low diffusion barrier, it could be concluded that the C3N/BlueP heterostructure is an appealing anode material for high-performance LIBs.

Designed lamination of binder-free flexible iron oxide/carbon cloth as high capacity and stable anode material for lithium-ion batteries

Free-standing binder-free electrodes have attracted significant attention towards high-performance lithium (Li)-ion batteries (LIBs). In this study, the Fe2O3 nanostructures with various morphologies were prepared by a simple one-step solvothermal method. The as-prepared nanostructured Fe2O3 was successfully grown on carbon cloth (CC) to form the flexible three-dimensional (3D) networked Fe2O3/CC composites via the same in-situ solvothermal method. The flexible 3D networked Fe2O3/CC composites could be directly used as an additive-free anode material for LIBs, which exhibited remarkable Li storage properties including high reversibility, excellent cycling stability, and high rate performance. The 3D networked Fe2O3/CC electrode promotes the permeation of electrolyte, shortens the Li-ion diffusion length, and provides a cushion for the volume expansion/contraction during Li-ion insertion/extraction process. Specifically, 3D networked Fe2O3@180-CC2 composite electrode delivered a high discharge capacity of 1350 mAh g−1 at 0.1 A g−1 over 100 cycles, showing the outstanding cycle life with a reversible capacity of 530 mAh g−1 at a 3 A g−1 over 700 cycles. Whereas, the pristine Fe2O3@180 electrode (prepared in a conventional way) delivered a discharge capacity of 758 mAh g−1 at 0.1 A g−1 over 100 cycles, which is relatively lower than the binder-free Fe2O3@180-CC2 electrode. The obtained excellent electrochemical results suggest that the 3D networked Fe2O3/CC composite electrode is a promising anode material for high-performance LIBs.

Hierarchical Porous NiO/β-NiMoO4 Heterostructure as Superior Anode Material for Lithium Storage.

Ternary transition metal oxides (TTMOs) have attracted considerable attention for rechargeable batteries because of their fascinating properties. However, the unsatisfactory electrochemical performance originating from the poor intrinsic electronic conductivity and inferior structural stability impedes their practical applications. Here, the novel hierarchical porous NiO/β-NiMoO4 heterostructure is fabricated, and exhibits high reversible capacity, superior rate capability, and excellent cycling stability in Li-ion batteries (LIBs), which is much better than the corresponding single-phase NiMoO4 and NiO materials. The significantly enhanced electrochemical properties can be attributed to its superior structural characteristics, including the large surface area, abundant pores, fast charge transfer, and catalytic effect of the intermediate product of metallic nickel. The NiO/β-NiMoO4 heterostructure delivers a high capacity of 1314 mA h g-1 at 0.2 A g-1 after 100 cycles. Furthermore, even after 400 cycles at 1 A g-1 , the reversible capacity remains at around 500 mA h g-1 . These results indicate that the NiO/β-NiMoO4 heterostructure shows great potential as an anode material for high-performance LIBs.

Siligraphene as a promising anode material for lithium-ion batteries predicted from first-principles calculations

Rational design of novel electrode materials with higher capacity is a key to further improve the energy density of Li-ion batteries (LIBs). Inspired by the high capacity of silicon anode, we here report for the first time a theoretical first-principles investigation into the scientific feasibility of using siligraphene (g-SiC5 and g-SiC2) as a high-capacity anode material for LIBs. The results show that siligraphene working as an LIB anode possesses the advantages of high stability from graphene and high capacity from silicene. While the pristine graphene offers limited Li storage capacity due to the weak Li/graphene interaction, the fundamental Li-Si chemistry ensures a strong Li adsorption in siligraphene and thus allows more Li to be stored. The monolayer siligraphene g-SiC5 and g-SiC2 can be lithiated into Li5SiC5 and Li5Si2C4, respectively, offering a respective theoretical capacity of 1520 mAh/g and 1286 mAh/g. On the other hand, the unique two dimensional honeycomb structure of siligraphene promotes a high electron and Li-ion conductivity to achieve fast cycling rate with negligible volume expansion. The mechanisms on how Si in siligraphene enhances Li/siligraphene interaction are particularly discussed. Overall, the results of this study provide a solid theoretical foundation for rational design of Si/C compounds as novel anode materials for high-performance LIBs.

Facile solution-free preparation of a carbon coated Fe3O4 nanoparticles/expanded graphite composite with outstanding Li-storage performances

A novel carbon coated Fe3O4 nanoparticles (NPs)/expanded graphite (EG) composite has been prepared by in-situ pyrolysis of ferrecene on the nanosheets (NSs) of EG in an isolated atmosphere. Results indicated that the restack behavior of the NSs of EG which is easy to be induced by solvent removal was effectively avoided by this solution-free route. Well-crystallized Fe3O4-NPs with a dimension of <5nm were observed to be homogeneously anchored on these NSs. The composite as anode material of Li-ion batteries (LIBs) exhibited prominently enhanced reversible capacity and rate capability, meanwhile inherited the superior cycling performance of EG. After 100 cycles at 100mAg−1, the charge capacity still reached 728mAhg−1, which was 283% higher than that of pure EG. The greatly improved electrochemical performances are ascribed to the favorable synergistic effect between carbon coated Fe3O4-NPs and EG, suggesting that the special Fe3O4-NPs/EG composite is promising anode material for high-performance LIBs.

Cobalt oxide modified porous carbon anode enhancing electrochemical performance for Li-ion batteries

A cobalt oxide modified porous carbon has been synthesized via a solvothermal method followed by a simple thermal treatment process. Scanning electron microscopy and transmission electron microscopy images reveal that Co3O4 nanoparticles (NPs) with sizes of 20–40nm are uniformly anchored onto porous carbon (PC). As an anode material for Li-ion batteries (LIBs), the composite exhibits enhanced reversible capacity, excellent cyclic performance, high Coulombic efficiency and good rate capability, which could be attributed to the 3D hierarchical porous structure of PC as well as the small size of the Co3O4 NPs providing convenient and accessible routs for electrolyte diffusion and intercalation of Li ions. Moreover, the interconnective networks of PC could decrease the inner resistance of LIBs and maintain structural stability. Thus the Co3O4/PC composite could be a promising anode material for high-performance LIBs.

A mesoporous WO3−X/graphene composite as a high-performance Li-ion battery anode

A novel mesoporous WO3−X/graphene composite was developed. This material allowed rapid electron and Li+ ion diffusion when used as a Li-ion battery (LIB) anode material. Remarkably, the graphene support protected WO3−X from changing volume during the electrochemical cycling process; this process generally induces capacity loss. The current work describes a high-performance anode material for LIB that has highly dense WO3−X, as well as high capacity, rate capability and stability.