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Ferroferric oxide (Fe3O4) is regarded to be a promising high-capacity anode material for LIBs. However, the capacity attenuates fast and the rate performance is poor due to the dramatic pulverization and sluggish charge transfer properties. To solve these problems, a simple in situ encapsulation and composite method was successfully developed to construct carbon nanotube/nanorod/nanosheet-supported Fe3O4 nanoparticles. Owing to the hierarchical architecture design, the novel structure Fe3O4@C nanocomposites effectively enhance the charge transfer, alleviate pulverization, avoid the agglomeration of Fe3O4 nanoparticles, and also provide superior kinetics toward lithium storage, thereby showing significantly improved reversibility and rate performance. The carbon nanotube/nanorod supported core-shell structure Fe3O4@C nanocomposite displays outstanding high rate capability and stable cycling performance (reversible capability of 1006, 552 and 423 mA h g−1 at 0.2, 0.5 and 1 A g−1 after running 100, 300 and 500 cycles, respectively). [ABSTRACT FROM AUTHOR]

Abstract Hybrid anodes with Li 4 Ti 5 O 12 nanoparticles uniformly embedding in a mesoporous activated carbon matrix are prepared by CO 2 activation of copolymerized resorcinol and hexamethylenetetramine loaded by lithium acetate and tetrabutyl titanate. The Li 4 Ti 5 O 12 /activated-carbon hybrid anodes show increased capacity retention as the activated carbon content in the composite increases, although their overall specific capacity decreases gradually. The hybrid anode with an activated-carbon content of 54 wt% exhibits the highest capacity retention of 67% at 4 A g−1 referencing to that at 0.1 A g−1. When coupling it with commercial AC cathode, the Li-ion capacitor displays an outstanding high energy density of 38 Wh kg−1 even at a high power density of 7964 W kg−1. Moreover, an energy density retention of 90.8% after 2000 cycles at 1 A g−1 is preserved, demonstrating its very stable cycle performance. The results reported in this work indicate that the Li 4 Ti 5 O 12 /activated-carbon hybrids prepared by the proposed copolymerization and post-activation process may be very promising anode materials of Li-ion capacitors designed for high power applications. Highlights • LTO-AC hybrid anodes were prepared by copolymerization and post-activation process. • LTO nanoparticles embedded in mesoporous AC matrix uniformly. • The LTO-AC hybrid anodes exhibited excellent rate capability and cycle performance. • High energy density of 38 Wh kg−1 was achieved at 7964 w kg−1. [ABSTRACT FROM AUTHOR]

A flexible, free-standing composite anode with Li 4 Ti 5 O 12 nanosheet arrays anchoring on plain-weaved carbon fiber cloth (LTO@CC) is prepared by a hydrothermal and post-annealing process assisted by a TiO 2 seed layer. The LTO@CC anode free from polymeric binder and conducting agent exhibited much higher lithium storage capacity and cycling stability than the conventional slurry-processed electrode using the dandelion-like Li 4 Ti 5 O 12 microspheres prepared by the same hydrothermal process. A high specific capacity of 128.8 mA h g −1 was obtained at a current rate of 30 C (1 C = 175 mA g −1 ), and almost negligible capacity loses was observed when the cell was cycled at 10, 20 and 30 C each for 100 cycles. The carbon fiber matrix contributed to Li storage at low current rate, but the LTO nanosheet arrays have played the dominant role on the excellent rate capability. The improved electrochemical performance can be attributed to the synergetic effect between the hierarchical Li 4 Ti 5 O 12 nanosheet arrays and the carbon fiber matrix, which integrated short Li + diffusion length, three-dimensional conductive architecture and well preserved structural integrity during the high rate and repeated charge-discharge measurements. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphite (MCMB) granulates were decorated with oxygen-deficient Nb 2 O 5-x nanoparticle. • The MCMB/Nb 2 O 5-x composite electrodes show much enhanced Li+ diffusion coefficient. • The composite electrodes exhibit better rate and cycle performances than pristine MCMB. • The Nb 2 O 5-x undergoes phase transition from crystalline to amorphous with formation of NbO. • The current-sharing effect of the secondary particles may help to improve the rate performance. Nanosized oxygen-deficient orthorhombic niobium pentoxide (Nb 2 O 5-x) that possess high electronic conductivity and stable cycle performance for Li storage are uniformly deposited on the surface of mesophase carbon microspheres (MCMB), which as a whole exhibits very encouraging electrochemical Li ion storage performance, including a high specific capacity of 107 mAh g−1 at 10C (1C = 372 mA g−1) and a high capacity retention of 85.4 % after 300 cycles at 3C in the optimized case. The Li+ diffusion coefficient of the composite anode as determined by the potentiostatic intermittent titration technique (PITT) is obviously improved as compared to that of pristine MCMB. Ex situ X-ray diffraction characterizations confirm the phase transformation from orthorhombic Nb 2 O 5-x to amorphous Li y Nb 2 O 5-x accompanied by the formation of NbO through a conversion reaction in the first lithiation process. The ultrafast Li+ diffusion within the amorphous Li y Nb 2 O 5-x as well as the current-sharing effect of the secondary particles can explain the much enhanced Li ion storage property. The results of this work convincingly demonstrate that designing MCMB/Nb 2 O 5-x composite can be a more practical way to improve the energy and powder densities of Li-ion batteries rather than seeking alternative anode materials with higher capacities. [ABSTRACT FROM AUTHOR]

A hierarchical polypyrrole interlayer was introduced on carbon cloth through a MnO 2 templating method to assist high mass loading of Li 4 Ti 5 O 12 nanosheets arrays for greatly enhanced Na ion storage capacity. • Free-standing LTO@CC anode with high mass loading was fabricated. • A rough polypyrrole interlayer was used to increase the mass loading of Li 4 Ti 5 O 12. • High areal Na storage capacities of LTO@CC anode were obtained. • Excellent rate capability and robust cycle stability were measured. A composite anode with a mass loading of Li 4 Ti 5 O 12 nanosheets arrays on carbon cloth up to 10.49 wt% was successfully prepared by a hierarchical polypyrrole interlayer assisted hydrothermal and post-annealing process. With this improved mass loading, the free-standing electrode exhibited high areal Na ion storage capacities of 0.57 mA h cm−2 at 0.05 mA cm−2 and 0.23 mA h cm−2 at 1 mA cm−2, respectively. Concerning to gravimetric specific capacity, high values of 180 mA h g−1 at 100 mA g−1 and 118 mA h g−1 at 1000 mA g−1 were obtained. In addition, excellent cycle stability at both 100 mA g−1 and 1000 mA g−1 was demonstrated due to the robust structural integrity. These excellent electrochemical properties convincingly suggested that the prepared composite can be a potential high capacity and long-life free-standing anode of flexible Na ion storage devices. [ABSTRACT FROM AUTHOR]

Conductive carbon additives play very important roles on the performance of Li-ion batteries (LIBs) although they only occupy a very small mass percentage in both cathode and anode. Building up a multidimensional carbonaceous conductive network on cathode with the optimized mass ratio of carbon black, carbon nanotubes (CNTs) and graphene has been verified to be able to enhance the Li-ion storage performance. Herein, we further demonstrate that applying ternary conductive additives is also very effective in improving the rate and cycle performances of graphite anode although the active material already possess high electronic conductivity. A conductive additive assembly of 2 wt% Super P, 1 wt% CNTs and 1 wt% graphene can weave up an efficient conducting pathway on the mesocarbon microbeads (MCMB) anode and enhance the cycle stability (344 mAh g−1 at 1 C after 200 cycles) and rate performance (226 mAh g−1 at 3 C). The coin-type full cell assembled with the optimized MCMB anode and NCM811 cathode also displays much improved rate capability and cycle stability. As is revealed, the multidimensional conducting network might has led to a more uniform and ion conductive SEI film on MCMB anode, which lowers the polarization and energy barrier for Li+ transportation. [Display omitted] • A multidimensional conducting network is constructed on MCMB anode by modifying the dispersion solvent. • A specific capacity of 344 mAh g−1 is preserved after 200 cycles at 1 C. • The multidimensional conducting network promotes the Li+ transfer in MCMB anode. • Using ternary conductive additives in graphite anode is a practical way to improve the performance of LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • SiO is modified with Nb 2 O 5 and N-doped carbon coating before mixing with graphite. • The SiO@Nb 2 O 5 @NC anode shows much enhanced cycle and rate performance. • The decoration of capacitive Nb 2 O 5 is responsible for the enhanced properties. • A low cost while high performance SiO@Nb 2 O 5 @NC/SG composite anode is reported. Although SiO/G (G denotes graphite) products are commercially available in nowadays, their scalable applications in Li-ion batteries are still limited by their poor stability and high cost. Herein, niobium oxide (Nb 2 O 5) with open tunnel structure is composited with SiO in combination with N-doped carbon (NC) coating, which have jointly enhanced the rate and cycle performance of the resulting SiO@Nb 2 O 5 @NC composite anodes. Under optimum conditions, a capacity retention of 74% is preserved after 200 cycles at 0.2 A g−1, together with a high capacity of 666 mA h g−1 at 3 A g−1. Ex situ XRD analysis reveals that Nb 2 O 5 is transformed to amorphous Li x Nb 2 O 5 and electrochemical-inert NbO in the first lithiation process. The former exhibits fast Li+ migration rate and capacitive Li ion storage behavior, which may help to improve the electrochemical performance of SiO. Further mixing the SiO@Nb 2 O 5 @NC composite with spent graphite extracted from used LiFePO 4 battery yields a high capacity and stable anode material that shows a high capacity retention of 79% after 500 cycles at 0.4 A g−1. This work may shed a light on the development of stable yet low cost SiO/G anode materials through pre-modification of SiO with Nb 2 O 5 and utilization of cheap graphite resource. [ABSTRACT FROM AUTHOR]

• The large size Co9S8@C nanosheets were prepared by introducing Co9S8-DETA (DETA=Diethylenetriamine) as the precursor. • The 2D lamellar structure significantly reduce ions diffusion path in the Co9S8@C electrode to improve the diffusion kinetics. • The Co9S8@C exhibit outstanding lithium storage than Co9S8 nanosheets, due to the amorphous carbon shells configuration. The cobalt sulfides have become the focus materials on the lithium ion batteries application in which the Co 9 S 8 with the nanosheet structure is the promising candidate for anode material in high-energy and high-power lithium ion batteries. By introducing a novel strategy with the organic-inorganic hybrid Co 9 S 8 -DETA (DETA=Diethylenetriamine) as the precursor, the large size Co 9 S 8 @C nanosheets have been successfully prepared via a calcination process. Due to uniform two-dimensional structure of Co 9 S 8 and the amorphous carbon layer coating, the as-prepared Co 9 S 8 @C nanosheets exhibited excellent lithium ion storage performance as an anode material. The reversible capacity could be retained at 595 mAh g−1 after 160 cycles at 0.2 A g−1. The excellent performances of this nanocomposite offer numerous opportunities for other sulfides as a new anode in lithium ion batteries. [ABSTRACT FROM AUTHOR]

Niobium tungsten oxides (Nb-W-O) have been verified as promising Li storage anodes because of their similar working voltage and cycling stability to Li 4 Ti 5 O 12 but higher specific capacity than the latter. However, the phase and microstructural evolutions of a designated Nb-W-O compound during sintering as well as its possible application in Li-ion hybrid capacitors have not been reported. In this work, micro-sized phase pure Nb 14 W 3 O 44 is obtained by sintering a solvothermal-derived precursor at about 1050 °C, which as a Li-ion insertion host exhibits not only high reversible specific capacity up to 226 mAh g−1 at 0.04 A g−1, but outstanding rate capability (137 mAh g−1 at 6 A g−1) and cycle stability (74.2% capacity retention at 2 A g−1 after 1000 cycles). Such an excellent rate capability enables the Nb 14 W 3 O 4 anode highly matchable to the capacitive cathode and yields high energy densities of 64.6 and 29.2 Wh kg−1 at 198.9 and 14,576 W kg−1, respectively, in Li-ion hybrid capacitors, along with a high capacity retention of 83.9% after 3,000 cycles at 1 A g−1. With these excellent electrochemical energy storage performances and a high packing density, the micro-sized Nb 14 W 3 O 44 can be a very promising anode material for both Li-ion batteries and Li-ion hybrid capacitors towards high energy-power outputs. [ABSTRACT FROM AUTHOR]