Nitridated mesoporous Li4Ti5O12 spheres for high-rate lithium-ion batteries anode material

Nitridated mesoporous Li₄Ti₅O₁₂ spheres were synthesized by a simple ammonia treatment of Li₄Ti₅O₁₂ derived from mesoporous TiO₂ particles and lithium acetate dihydrate via a solid state reaction in the presence of polyethylene glycol 20000. The carbonization of polyethylene glycol could effectively restrict the growth of primary particles, which was favorable for lithium ions diffusing into the nanosized TiO₂ lattice during the solid state reaction to form a pure phase Li₄Ti₅O₁₂. After a subsequent thermal nitridation treatment, a high conductive thin TiO _x N _y layer was in situ constructed on the surface of the primary nanoparticles. As a result, the nitridated mesoporous Li₄Ti₅O₁₂ structure, possessing shorter lithium-ion diffusion path and better electrical conductivity, displays significantly improved rate capability. The discharge capacity reaches 138 mAh?g^?1 at 10 C rate and 120 mAh?g^?1 at 20 C rate in the voltage range of 1–3 V.     

Synthesis of MgCo2O4-coated Li4Ti5O12 composite anodes using co-precipitation method for lithium-ion batteries

Journal of Solid State Electrochemistry - In the present work, we report synthesis of MgCo2O4 (MCO)/Li4Ti5O12 (LTO) composites for Li-ion battery anodes by a co-precipitation method. The objective...     

Synthesis and electrochemical performance of nanoporous Li4Ti5O12 anode material for lithium-ion batteries

Nanoporous Li₄Ti₅O₁₂ (N-LTO) was prepared by sol–gel method using monodisperse polystyrene spheres as a template and followed by calcination process. The as-prepared N-LTO has a spinel structure, large special surface area, and nanoporous structure with the pore average diameter of about 100?nm and wall thickness of 50?nm. Electrochemical experiments show that N-LTO exhibits a high initial discharge capacity of 189?mAh?g^?1 at 0.1?C rate cycled between 0.5 and 3.0?V and excellent capacity retention of 170?mAh?g^?1 after 100?cycles. EIS and CV analysis show that N-LTO has a higher mobility for Li⁺ diffusion and a higher exchange current density, indicating an improved electrochemical performance. It is believed that the nanoporous structure has a larger electrode/electrolyte contact area, resulting in better electrochemical properties at high charge/discharge rates.     

Synthesis of Li4Ti5O12 fibers as a high-rate electrode material for lithium-ion batteries

Porous lithium titanate (Li₄Ti₅O₁₂) fibers, composed of interconnected nanoparticles, are synthesized by thermally treating electrospun precursor fibers and utilized as an energy storage material for rechargeable lithium-ion batteries. The material is characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and thermal analysis. Scanning electron microscopy results show that the Li₄Ti₅O₁₂ fibers calcined at 700?°C have an average diameter of 230?nm. Especially, the individual fiber is composed of nanoparticles with an average diameter of 47.5?nm. Electrochemical properties of the material are evaluated using cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy. The results show that as-prepared Li₄Ti₅O₁₂ exhibits good cycling capacity and rate capability. At the charge–discharge rate of 0.2, 0.5, 1, 2, 10, 20, 40, and 60?C, its discharge capacities are 172.4, 168.2, 163.3, 155.9, 138.7, 123.4, 108.8, and 90.4?mAh?g^?1, respectively. After 300 cycles at 20?C, it remained at 120.1?mAh?g^?1. The obtained results thus strongly support that the electrospun Li₄Ti₅O₁₂ fibers could be one of the most promising candidate anode materials for lithium-ion batteries in electric vehicles.     

Carbon-coated Li4Ti5O12 microspheres synthesized through solid-state reaction in a carbon reduction atmosphere for high-rate lithium-ion batteries

Journal of Solid State Electrochemistry - Carbon coating combined with morphological engineering has been considered an effective and economical measure for enhancing the electrochemical properties...     

Boosting the electrochemical performance of Li4Ti5O12 through nitrogen‐doped carbon coating

The poor electronic conductivity restricts the wide applications of Li₄Ti₅O₁₂ as anode materials in Li‐ion batteries. We report a facile approach to fabricate nitrogen‐doped carbon‐coated Li₄Ti₅O₁₂ through carbonizing pyrrole and pyridine at different temperatures. Comparative experiments demonstrated that the carbon content plays a key role in governing the cycling performance and rate capability of Li₄Ti₅O₁₂. The composites with higher carbon content exhibited superior cycling performance, and the composite prepared at 600 °C using pyridine as the carbon source gave the best cycling and rate performance.     

Synthesis and electrochemical performances of Li4Ti4.95Zr0.05O12/C as anode material for lithium-ion batteries

Spinel Li₄Ti_5 − x Zr _x O₁₂/C (x = 0, 0.05) were prepared by a solution method. The structure and morphology of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The electrochemical performances including charge–discharge (0–2.5 V and 1–2.5 V), cyclic voltammetry, and ac impedance were also investigated. The results revealed that the Li₄Ti_4.95Zr_0.05O₁₂/C had a relatively smaller particle size and more regular morphology than that of Li₄Ti₅O₁₂/C. Zr⁴⁺ doping enhanced the ability of lithium-ion diffusion in the electrode. It delivered a discharge capacity 289.03 mAh g⁻¹ after 50 cycles for the Zr⁴⁺-doped Li₄Ti₅O₁₂/C while it decreased to 264.03 mAh g⁻¹ for the Li₄Ti₅O₁₂/C at the 0.2C discharge to 0 V. Zr⁴⁺ doping did not change the electrochemical process, instead enhanced the electronic conductivity and ionic conductivity. The reversible capacity and cycling performance were effectively improved especially when it was discharged to 0 V.     

C/C composite anodes for long-life lithium-ion batteries

The research of anodic materials which could improve the performance and reduce the cost of graphite-based materials in lithium-ion batteries leads to a considerable effort for creating novel carbons. In this work, special attention has been paid to investigating the possibility of improving the electrochemical behavior of graphite anode by application of composite materials with carbon materials coming from agro-wastes. For that, different carbons coming from agro-wastes have been synthesized and characterized in order to study the effect of their properties on the electrochemical performance of C/C composites with graphite. It has been established that introduction of hard carbon obtained from olive stones into the active mass of anode based on graphite allows one to increase the reversible capacity up to 405 mAh g^?1 for the total mass of graphite/carbon content of electrode, and also to improve stability of characteristics during cycling. We suggested that such a binary carbon mixture (graphite and hard carbon) would be a better choice for development of the anode for lithium-ion battery.     

Electrochemical performance of Li4Ti5O12/carbon nanofibers composite prepared by an in situ route for Li-ion batteries

A Li₄Ti₅O₁₂/carbon nanofibers (LTO/CNFs) composite has been synthesized by solid-state reaction with the in situ growth of CNFs using the chemical vapor deposition method in N₂/C₂H₂. The nanocomposite is characterized by X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy, Raman spectrum, and nitrogen adsorption/desorption isotherms, and is investigated as an anode material for lithium-ion (Li-ion) batteries. The underlying mechanism for the improvement is analyzed by cyclic voltammetry and electrochemical impedance spectroscopy. The in situ synthesized composite shows better electrochemical performance than the bare LTO. The in situ formation of CNFs not only supply an efficient electronic conductive network but also reduce the particle size of LTO and increase in specific surface area, leading to increased electrical conductivity and rapider Li-ion diffusion in electrode/electrolyte interface and bulk electrode.     

Li4Ti5O12/reduced graphite oxide nano-hybrid material for high rate lithium-ion batteries

A spinel Li₄Ti₅O₁₂ nanoplatelet/reduced graphite oxide nano-hybrid was successfully synthesized by a two-step microwave-assisted solvothermal reaction and heat treatment. The Li₄Ti₅O₁₂ in the hybrid could deliver a discharge capacity of 154 mAhg^? 1 of Li₄Ti₅O₁₂ at 1 C-rate, 128 mAhg^-1 of Li₄Ti₅O₁₂ at 50 C-rate and 101 mAhg^-1 of Li₄Ti₅O₁₂ at 100 C-rate. It demonstrated promising potential as an anode material in a Li-ion battery with excellent rate capability and good cycling.     

Rutile-TiO2 nanocoating for a high-rate Li4Ti5O12 anode of a lithium-ion battery

Well-defined Li(4)Ti(5)O(12) nanosheets terminated with rutile-TiO(2) at the edges were synthesized by a facile solution-based method and revealed directly at atomic resolution by an advanced spherical aberration imaging technique. The rutile-TiO(2) terminated Li(4)Ti(5)O(12) nanosheets show much improved rate capability and specific capacity compared with pure Li(4)Ti(5)O(12) nanosheets when used as anode materials for lithium ion batteries. The results here give clear evidence of the utility of rutile-TiO(2) as a carbon-free coating layer to improve the kinetics of Li(4)Ti(5)O(12) toward fast lithium insertion/extraction. The carbon-free nanocoating of rutile-TiO(2) is highly effective in improving the electrochemical properties of Li(4)Ti(5)O(12), promising advanced batteries with high volumetric energy density, high surface stability, and long cycle life compared with the commonly used carbon nanocoating in electrode materials.     

Impact of titanium precursors on formation and electrochemical properties of Li4Ti5O12 anode materials for lithium-ion batteries

This work describes comparative study on the application of Li₄Ti₅O₁₂ (LTO) as anode materials for lithium-ion batteries which were successfully prepared by sol-gel synthesis with the use of two titanium sources. One of them was anatase-type titanium dioxide (TiO₂), whereas the second was tetrabutyl titanate (TBT). Both obtained LTO materials were very similar in terms of their crystallinity and purity. In turn, the sample synthetized with TBT source revealed better particle dispersibility, and its particles were slightly lower in size. These particular features resulted in higher Li⁺ diffusion coefficient and better kinetic of Li⁺ ions during charge transfer reactions for the LTO synthetized with TBT source. This reflected in specific capacitance values for both electrodes which equalled 150 mAh g⁻¹, 120 mAh g⁻¹, and 63 mAh g⁻¹ for TBT-LTO and 120 mAh g⁻¹, 80 mAh g⁻¹, and 58 mAh g⁻¹ for TiO₂-LTO at C-rates of 1, 5, and 10 C, respectively.

     

Nano-structured Li3V2(PO4)3/carbon composite for high-rate lithium-ion batteries

Nano-structured Li₃V₂(PO₄)₃/carbon composite (Li₃V₂(PO₄)₃/C) has been successfully prepared by incorporating the precursor solution into a highly mesoporous carbon with an expanded pore structure. X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy were used to characterize the structure of the composites. Li₃V₂(PO₄)₃ had particle sizes of < 50 nm and was well dispersed in the carbon matrix. When cycled within a voltage range of 3 to 4.3 V, a Li₃V₂(PO₄)₃/C composite delivered a reversible capacity of 122 mA h g^? 1 at a 1C rate and maintained a specific discharge capacity of 83 mA h g^? 1 at a 32C rate. These results demonstrate that cathodes made from a nano-structured Li₃V₂(PO₄)₃ and mesoporous carbon composite material have great potential for use in high-power Li-ion batteries.     

Porous spheres consisting of Li4Ti5O12 nanocrystals prepared through spray drying and their application as anodes for lithium-ion batteries

Journal of Solid State Electrochemistry - In this study, a facile method is developed for preparing porous microspheres of lithium titanate (Li4Ti5O12 [LTO]) nanocrystals for use as anode materials...     

Epitaxial growth and electrochemical properties of Li4Ti5O12 thin-film lithium battery anodes

Epitaxial Li(4)Ti(5)O(12) thin-films were successfully synthesized on SrTiO(3) single-crystal substrates with (111), (110), and (100) lattice plane orientations using pulsed laser deposition (PLD). Thin-film X-ray diffraction (XRD) revealed that the Li(4)Ti(5)O(12) films had the same orientation as the SrTiO(3) substrates: Li(4)Ti(5)O(12) (111) on SrTiO(3) (111), Li(4)Ti(5)O(12) (110) on SrTiO(3) (110), and Li(4)Ti(5)O(12) (100) on SrTiO(3) (100). These epitaxial films contained island structures, and the morphology of the (111), (110), and (100) films, observed by field emission scanning electron microscopy (FE-SEM), exhibited angular, needle-like, and circular shapes, respectively. The electrochemical properties of 20 nm thick Li(4)Ti(5)O(12) (111) and (110) films were investigated by cyclic voltammetry. Reversible intercalation proceeded through both lattice planes due to the three-dimensional diffusion pathway of lithium in the spinel framework. Reduction peaks in the first cathodic scan appeared at different positions from those in subsequent scans, suggesting a surface reconstruction at the Li(4)Ti(5)O(12) surface due to interfacial reactions.     

Nitridation-driven conductive Li4Ti5O12 for lithium ion batteries

To modify oxide structure and introduce a thin conductive film on Li4Ti5O12, thermal nitridation was adopted for the first time. NH3 decomposes surface Li4Ti5O12 to conductive TiN at high temperature, and surprisingly, it also modifies the surface structure in a way to accommodate the single phase Li insertion and extraction. The electrochemically induced Li4+deltaTi5O12 with a TiN coating layer shows great electrochemical properties at high current densities.     

Preparation and electrochemical performance of monodisperse Li4Ti5O12 hollow spheres

Monodisperse Li₄Ti₅O₁₂ hollow spheres were prepared by using carbon spheres as templates. Scanning electron microscopy images show hollow spheres that have an average outer diameter of 1.0 μm and an average wall thickness of 60 nm. Compared with Li₄Ti₅O₁₂ solids, the hollow spherical Li₄Ti₅O₁₂ exhibit an excellent rate capability and capacity retention and can be charged/discharged at 10 C (1.7 A g⁻¹) with a specific capacity of 100 mA h g⁻¹, and after 200 charge and discharge cycles at 2 C, their specific capacity remain very stable at 150 mA h g⁻¹. It is believed that the hollow structure has a relatively large contact surface between Li₄Ti₅O₁₂ and liquid electrolyte, resulting in a better electrochemical performance at high charge/discharge rate.