Li 2 TiO 3 /Graphene and Li 2 TiO 3 /CNT Composites as Anodes for High Power Li-Ion Batteries

International audienceThree-dimensional composites Li2TiO3/graphene (LTO/Gr) and Li2TiO3/carbon nanotube (LTO/CNTs) were synthesized by solid-state reaction for application as anode materials for lithium-ion batteries. These composites are structurally characterized by X-ray diffraction, Raman spectroscopy and high-resolution transmission electron microscopy, while electrochemically tests are performed by cyclic voltammetry and chronopotentiometry. The synergetic effect of graphene and CNTs with LTO facilitate the network conduction leading to faster electron and Li + ion transfer and improve cycling stability and rate capability of the anode. The LTO/Gr and LTO/CNTs composites exhibited an initial discharge capacity as high as 154 and 149 mAh g-1 at 1C rate, respectively and retained excellent cycling stability of 98% and 96% after 30 charge-discharge cycles

Electrochemical Performance of Li₂TiO₃//LiCoO₂ Li-Ion Aqueous Cell with Nanocrystalline Electrodes

A challenge in developing high-performance lithium batteries requires a safe technology without flammable liquid electrolytes. Nowadays, two options can satisfy this claim: all-solid-state batteries and aqueous-electrolyte batteries. Commercially available Li-ion batteries utilize non-aqueous electrolytes (NAE) owing to a wide potential window (>3 V) that achieves high energy density but pose serious safety issues due to the high volatility, flammability, and toxicity of NAE. On the contrary, aqueous electrolytes are non-flammable, low-toxic, and have a low installation cost for humidity control in the production line. In this scenario, we develop a new aqueous rechargeable Li-ion full-cell composed of high-voltage cathode material as LiCoO2 (LCO) and a safe nanostructured anode material as Li2TiO3 (LTO). Both pure-phase LTO and LCO nanopowders are prepared by hydrothermal route and their structural and electrochemical properties are studied in detail. Simultaneously, the electrochemical performances of these electrodes are tested in both half- and full-cell configurations in presence of saturated 1 mole L−1 Li2SO4 aqueous electrolyte medium. Pt//LCO and Pt//LTO half-cells deliver high discharge capacities of 142 and 133 mAh g−1 at 0.5 C rate with capacity retention of ~95% and 94% after 50 cycles with a Coulombic efficiency of 98.25% and 99.89%, respectively. The electrochemical performance of a LTO//LCO full cell is investigated for the first time. It reveals a discharge capacity of 135 mAh g−1 at 0.5 C rate (50th cycle) with a capacity retention of 94% and a Coulombic efficiency of 99.7%

Electrochemical Performance of Li2TiO3//LiCoO2 Li-Ion Aqueous Cell with Nanocrystalline Electrodes

A challenge in developing high-performance lithium batteries requires a safe technology without flammable liquid electrolytes. Nowadays, two options can satisfy this claim: all-solid-state batteries and aqueous-electrolyte batteries. Commercially available Li-ion batteries utilize non-aqueous electrolytes (NAE) owing to a wide potential window (>3 V) that achieves high energy density but pose serious safety issues due to the high volatility, flammability, and toxicity of NAE. On the contrary, aqueous electrolytes are non-flammable, low-toxic, and have a low installation cost for humidity control in the production line. In this scenario, we develop a new aqueous rechargeable Li-ion full-cell composed of high-voltage cathode material as LiCoO2 (LCO) and a safe nanostructured anode material as Li2TiO3 (LTO). Both pure-phase LTO and LCO nanopowders are prepared by hydrothermal route and their structural and electrochemical properties are studied in detail. Simultaneously, the electrochemical performances of these electrodes are tested in both half- and full-cell configurations in presence of saturated 1 mole L−1 Li2SO4 aqueous electrolyte medium. Pt//LCO and Pt//LTO half-cells deliver high discharge capacities of 142 and 133 mAh g−1 at 0.5 C rate with capacity retention of ~95% and 94% after 50 cycles with a Coulombic efficiency of 98.25% and 99.89%, respectively. The electrochemical performance of a LTO//LCO full cell is investigated for the first time. It reveals a discharge capacity of 135 mAh g−1 at 0.5 C rate (50th cycle) with a capacity retention of 94% and a Coulombic efficiency of 99.7%

Enhanced Electrochemical Performance of Rare-Earth Metal-Ion-Doped Nanocrystalline Li₄Ti₅O₁₂ Electrodes in High-Power Li-Ion Batteries

A comprehensive and comparative exploration research performed, aiming to elucidate the fundamental mechanisms of rare-earth (RE) metal-ion doping into Li4Ti5O12 (LTO), reveals the enhanced electrochemical performance of the nanocrystalline RE-LTO electrodes in high-power Li-ion batteries. Pristi ne Li4Ti5O12 (LTO) and rare-earth metal-doped Li4–x/3Ti5–2x/3LnxO12 (RE-LTO with RE = Dy, Ce, Nd, Sm, and Eu; x ≈ 0.1) nanocrystalline anode materials were synthesized using a simple mechanochemical method and subsequent calcination at 850 °C. The X-ray diffraction (XRD) patterns of pristine and RE-LTO samples exhibit predominant (111) orientation along with other characteristic peaks corresponding to cubic spinel lattice. No evidence of RE-doping-induced changes was seen in the crystal structure and phase. The average crystallite size for pristine and RE-LTO samples varies in the range of 50–40 nm, confirming the formation of nanoscale crystalline materials and revealing the good efficiency of the ball-milling-assisted process adopted to synthesize nanoscale particles. Raman spectroscopic analyses of the chemical bonding indicate and further validate the phase structural quality in addition to corroborating with XRD data for the cubic spinel structure formation. Transmission electron microscopy (TEM) reveals that both pristine and RE-LTO particles have a similar cubic shape, but RE-LTO particles are better interconnected, which provide a high specific surface area for enhanced Li+-ion storage. The detailed electrochemical characterization confirms that the RE-LTO electrodes constitute promising anode materials for high-power Li-ion batteries. The RE-LTO electrodes deliver better discharge capacities (in the range of 172–198 mAh g–1 at 1C rate) than virgin LTO (168 mAh g–1). Among them, Eu-LTO provides the best discharge capacity of 198 mAh g–1 at a 1C rate. When cycled at a high current rate of 50C, all RE-LTO electrodes show nearly 70% of their initial discharge capacities, resulting in higher rate capability than virgin LTO (63%). The results discussed in this work unfold the fundamental mechanisms of RE doping into LTO and demonstrate the enhanced electrochemical performance derived via chemical composition tailoring in RE-LTO compounds for application in high-power Li-ion batteries