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The present article introduces a strategy for controlling oxidation and reduction reactions within polymer electrolyte membrane (PEM) networks as a means of enhancing storage capacity through the complexation of dissociated lithium cations with multifunctional groups of the polymer network. Specifically, co-polymer networks based on polysulfide (PS) and polyoxide (PO) precursors, photo-cured in the presence of succinonitrile (SCN) and lithium bis(trifluoro methane sulfonyl imide) (LiTFSI) salt, exhibited ionic conductivity on the order of mid 10−4 S/cm at ambient temperature in the 30/35/35 (weight %) composition. Lithium titanate (LTO, Li4Ti5O12) electrode was chosen as an anode (i.e., a potential source of Li ions) against lithium iron phosphate (LFP, LiFePO4) cathode in conjunction with polysulfide-co-polyoxide dual polyelectrolyte networks to control viscosity for 3D printability on conformal surfaces of drone and aeronautic vehicles. It was found that the PS-co-PO dual network-based polymer electrolyte containing SCN plasticizer and LiTFSI salt exhibited extra storage capacity (i.e., specific capacity of 44 mAh/g) with the overall specific capacity of 170 mAh/g (i.e., for the combined LTO electrode and PEM) initially that stabilized at 153 mAh/g after 50th cycles with a reasonable capacity retention of over 90% and Coulombic efficiency of over 99%. Of particular interest is the observation of the improved electrochemical performance of the polysulfide-co-polyoxide electrolyte dual-network relative to that of the polyoxide electrolyte single-network. [ABSTRACT FROM AUTHOR]

The present article introduces a strategy for controlling oxidation and reduction reactions within polymer electrolyte membrane (PEM) networks as a means of enhancing storage capacity through the complexation of dissociated lithium cations with multifunctional groups of the polymer network. Specifically, co-polymer networks based on polysulfide (PS) and polyoxide (PO) precursors, photo-cured in the presence of succinonitrile (SCN) and lithium bis(trifluoro methane sulfonyl imide) (LiTFSI) salt, exhibited ionic conductivity on the order of mid 10−4 S/cm at ambient temperature in the 30/35/35 (weight %) composition. Lithium titanate (LTO, Li4Ti5O12) electrode was chosen as an anode (i.e., a potential source of Li ions) against lithium iron phosphate (LFP, LiFePO4) cathode in conjunction with polysulfide-co-polyoxide dual polyelectrolyte networks to control viscosity for 3D printability on conformal surfaces of drone and aeronautic vehicles. It was found that the PS-co-PO dual network-based polymer electrolyte containing SCN plasticizer and LiTFSI salt exhibited extra storage capacity (i.e., specific capacity of 44 mAh/g) with the overall specific capacity of 170 mAh/g (i.e., for the combined LTO electrode and PEM) initially that stabilized at 153 mAh/g after 50th cycles with a reasonable capacity retention of over 90% and Coulombic efficiency of over 99%. Of particular interest is the observation of the improved electrochemical performance of the polysulfide-co-polyoxide electrolyte dual-network relative to that of the polyoxide electrolyte single-network.

The high energy density and stability of solid‐state lithium batteries (SSBs) have garnered attention. Garnet electrolytes are widely explored in SSBs due to their huge electrochemical potential window, high effective ionic conductivity, and reasonable production cost. However, the electrochemical stability of a metallic lithium anode and a garnet electrolyte pose obstacles to the widespread use of garnet‐based SSBs. To remedy these problems, Li4Ti5O12 (LTO) is added to the metallic lithium anode. With superior wettability on the garnet electrolyte compared to pure metallic Li, Li–LTO is a more desirable electrolyte. Increased wettability between the garnet electrolyte and Li–LTO composite is responsible for the larger absolute value of the interface formation energy found in the first principal density‐functional theory calculation. Since the interface resistance between the Li–LTO composite anodes (25 Ω cm2) and the Li metal (270 Ω cm2) is much lower, Li dendrite development is effectively suppressed. An all‐lithium battery with a Li–LTO anode and a LiFePO4 cathode shows excellent capacity retention of 95% after 450 cycles. This discovery may serve as inspiration for future efforts to create a metallic Li‐containing anode for lithium batteries and other functional LTO‐based composites.

Abstract Significant safety advantages of lithium titanium oxide (LTO) over currently used graphite for lithium-ion batteries have been attracting scientists to develop novel synthetic methods of this anode material in order to combine with another cathode. This study utilizes self-sacrificing cross-linked aqueous templates of gelatin and chitosan polymer to control lithium titanium oxide (LTO) morphology and microstructure. Gelatin and chitosan self-assembled aqueous template containing LTO precursors has been evaporated at 110 °C and then calcined at 750 °C in a muffle furnace to synthesize white color LTO powder. Various techniques such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Energy dispersive x-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and UV–visible spectroscopy were used to characterize the synthesized LTO powders. Both XRD and EDS spectrum confirm the coating of gelatin and chitosan derived carbon species on the surface of LTO materials. The detailed characterization reveals that increasing the amount of gelatin to the mass ratio of gelatin and chitosan reduced LTO particle sizes. Thus, a size controlled carbon coating LTO preparation strategy have been established via gelatin and chitosan cross-linked aqueous template in controlling the morphology and microstructure of LTO material.

Lithium titanium oxide (Li 2 TiO 3) tritium breeder ceramic plates with nano- and coarse-grain size were fabricated. The preparation methods contained CTAB-modifying precursor, combining dry-pressing with isostatically cold-pressing, and calcinating at optimized sintering temperature in turn. Then their properties were characterized after radiation by 280 keV helium (He+) ion. Extensive characterization analyses were performed to reveal the changes in nano-grained and coarse-grained Li 2 TiO 3 after radiation. They contained glancing angle X-ray diffraction (GIXRD), atomic force microscopy (AFM), electron spin resonance (ESR), and scanning electron microscopy (SEM). The results showed as follows, GIXRD peak position of the nano-grained Li 2 TiO 3 was more stable than the coarse-grained Li 2 TiO 3 after radiation. Nano-grained Li 2 TiO 3 was less rough and swollen than the coarse-grained one after radiation. Nano-grained Li 2 TiO 3 had more excellent structural stability and less defect concentration of Eʹ-center after radiation. As a result, nano-grained Li 2 TiO 3 might have much better radiation tolerance than the coarse-grained one by comparing characterization results. [ABSTRACT FROM AUTHOR]

The degradation of LiNi0.5Mn1.5O4 (LNMO) cathodes were investigated using different cell designs (half cells, full cells cathode-limited, anode-limited and cathode-limited with pre-charge). Half cells based on Li/LNMO show long-cycle stability due to the unlimited source of electrochemically available lithium. Full-cell configurations with Li4Ti5O12/LNMO are limited in their cycling performance and durability. Differential capacity studies during continuous cycling reveal a systematic intensity change of the NiII/III and NiIII/IV redox peaks as a function of the amount of electrochemically available lithium. As a mechanism, it could be clearly stated that the consumption of electrochemically available lithium determines the cycle stability. The decomposition of the active material itself (e.g. loss of Ni and Mn) is not crucial for the capacity loss. Thus, full cells with a pre-charged anode have the best cycling performance because of its high lithium content.

This paper introduces the novel anode material which is Li4Ti5O12/Si prepared by gas-stated method, mainly spray-pyrolysis technique. The literature review performed in this paper revealed two main components which can be potentially mixed into the efficient anode material. Silicon (Si) has the highest possible capacity of 4200 mAh g-1 among all commonly used anodes. Due to its ‘zero-strain’ (

In this study, spinel lithium titanate (Li 4 Ti 5 O 12 , LTO) anode materials were synthesized from two titanium sources (P25 TiO 2 , 100% anatase TiO 2) using a spray-drying method and subsequent calcination at various temperatures. The electrochemical performance of both a Li/LTO half cell and a LiNi 0.5 Mn 1.5 O 4 /LTO (LNMO/LTO) full cell were investigated. The electrochemical performance of the LTO material prepared from P25 TiO 2 was superior to that of the LTO prepared from 100% anatase TiO 2. After modification of LTO material with AlPO 4 , the LTO coated with 2 wt% of AlPO 4 (denoted "2%AlPO 4 -LTO") provided the best performances. The specific (delithiation) capacities of the 2%AlPO 4 -LTO anode material was 189.7 mA h g−1 at 0.1C/0.1C, 184.5 mA h g−1 at 1C/1C, 178.8 mA h g−1 at 5C/5C, and 173.1 mA h g−1 at 10C/10C. From long-term cycling stability tests, the specific capacity at the first cycle and the capacity retention after cycling were 185.5 mA h g−1 and 98.06%, respectively, after 200 cycles at 1C/1C and 182.1 mA h g−1 and 99.18%, respectively, after 100 cycles at 1C/10C. For the LNMO/2%AlPO 4 -LTO full cell, the average specific capacity (delithiation) and coulombic efficiency after the first five cycles were 164.8 mA h g−1 and 93.30%, respectively, at 0.1C/0.1C. The specific capacities at higher C-rates were 156.1 mA h g−1 at 0.2C/0.2C, 135.7 mA h g−1 at 1C/1C, 97.5 mA h g−1 at 3C/3C, and 46.5 mA h g−1 at 5C/5C. After twenty-five cycles, the C-rate returned to 1C/1C and the specific capacity, coulombic efficiency, and capacity retention were maintained at 134.1 mA h g−1, 99.17%, and 98.82%, respectively. [ABSTRACT FROM AUTHOR]

For implanted medical devices containing rechargeable batteries, maximizing battery lifetime is paramount as surgery is required for battery replacement. In non-life-sustaining applications (e.g., spinal cord stimulators or sacral nerve modulation), these implants may be left unused and unmaintained for extended periods, according to patient preference or in the case of unexpected life events. In this study, we examine the performance of two commercial lithium-ion cells intended for implantable neurostimulators (using lithium titanium oxide (LTO) and graphite as the negative electrode) when subjected to repeated deep overdischarge and to aging at a high state of charge (SOC). The graphite-based cells exhibited significant performance decline and swelling after overdischarge and became unable to store a charge after 42 days at 0 V. In contrast, the LTO-based cells exhibited minimal changes in performance even after 84 days (the length of the study) at 0 V. When subjected to an accelerated aging protocol at 100% SOC, the graphite-based cells were found to age more rapidly than the LTO cells, which exhibited minimal aging over the course of the study period. These results show that practical LTO-based lithium-ion cells are much more tolerant of abuse as a result of neglect and misuse and are worth considering for use in high-value applications where battery replacement is difficult or impossible.

The degradation of LiNi0.5Mn1.5O4 (LNMO) cathodes were investigated using different cell designs (half cells, full cells cathode-limited, anode-limited and cathode-limited with pre-charge). Half cells based on Li/LNMO show long-cycle stability due to the unlimited source of electrochemically available lithium. Full-cell configurations with Li4Ti5O12/LNMO are limited in their cycling performance and durability. Differential capacity studies during continuous cycling reveal a systematic intensity change of the NiII/III and NiIII/IV redox peaks as a function of the amount of electrochemically available lithium. As a mechanism, it could be clearly stated that the consumption of electrochemically available lithium determines the cycle stability. The decomposition of the active material itself (e.g. loss of Ni and Mn) is not crucial for the capacity loss. Thus, full cells with a pre-charged anode have the best cycling performance because of its high lithium content. [ABSTRACT FROM AUTHOR]

Abstract We report a novel and versatile method of grafting polymers onto lithium titanium oxide (LTO) by dispersion-mediated interfacial polymerization. A myriad of polymers can be grafted by this method, and the hybrid-polymer particles are compatible with all kinds of binders used in lithium-ion batteries. This method is capable of producing thin and homogenous polymer films that are useful for battery applications. A coating of poly(styrene) effectively prevents degradation of the cell after float test without affecting performance at high C rates. Graphical abstract Image 1 Highlights • Versatile method of grafting polymers onto lithium titanium oxide (LTO) is reported. • Hybrid-polymer particles are compatible with all kinds of binders. • Effect of different polymer coatings on cell performances is investigated. • Poly(styrene) coating mitigates degradation of cell after float test. [ABSTRACT FROM AUTHOR]

In this study, Li4Ti5O12 (LTO) electrodes with different types of water-soluble binders are successfully coated upon aluminum foil. Electrodes containing solely sodium alginate (SA) as a binder or a mixed PVDF/carboxymethyl cellulose (CMC) binder show the most stable performance in 1 M LiPF6 in EC/DMC 1:1 in half cell vs. Li, with respect to cycle stability over 100 cycles at 1 C. The electrodes processed with a mixture of PVDF/SA show considerable fading and slightly worse values for rate capability. Each one of the different binders used is eco-friendly, and the whole processing can be performed without the use of organic solvents. Further advantages covering the whole production and recycling process, as well as safety issues during operation, encourage deeper research in this area.

X-ray photoelectron spectroscopy (XPS) and x-ray-induced Auger electron spectroscopy were used to analyze untreated Li4Ti5O12 powders obtained from Ishihara Sangyo Kaisha, Ltd. and Samsung Fine Chemicals Company, Ltd. X-ray photoelectron and x-ray-induced Auger electron spectra were obtained using incident monochromatic Al Kα radiation at 0.834 01 nm. A survey spectrum together with O 1s, Ti 2p, C 1s, Ti 3s, Li 1s, and Ti 3p are presented. The spectra indicate the principal core level photoelectron and Auger electron signals and show only minor potassium signal. Making use of the O 1s, Li 1s, and Ti 3p lines and neglecting the components related to surface contaminants, XPS quantitative analysis reveals an altered stoichiometry of the air-exposed powder surfaces from Ishihara Sangyo Kaisha, Ltd. and Samsung Fine Chemicals Company, Ltd. of Li4Ti4.7O14.1 and Li4Ti4.3O13.2, respectively. [ABSTRACT FROM AUTHOR]

This paper introduces the novel anode material which is Li4Ti5O12/Si prepared by gasstated method, mainly spray-pyrolysis technique. The literature review performed in this paper revealed two main components which can be potentially mixed into the efficient anode material. Silicon (Si) has the highest possible capacity of 4200 mAh g-1 among all commonly used anodes. Due to its 'zero-strain' (<1% volume change) properties and stable cycling, Li4Ti5O12 (LTO) is considered as a promising anode for lithium ion batteries. Combination of these two anode materials is considered as a promising approach to prepare a high performance composite anode. The precursor solution consisted of homogeneous mixture of lithium nitrate and titanium tetraisopropoxide dissolved in deionized water with equimolar concentration of 0.5 M. The aerosol formation was performed at nitrogen environment and the droplets were carried into the quartz tube reactor at the flowrate of 4 L min-1. The rector temperature was held at 800 °C. The spray-pyrolysis synthesis was performed as one-step operation, excluding the need of calcination of as-prepared powders, and continuous process by the mean of peristaltic pump. The as-prepared powders had wide size distribution from nanometers to microns. The materials obtained had well-crystallized structure with insignificant amount of impurities. The powders were analyzed by the following analytical equipment: 1) the presence of Li4Ti5O12 and Si in the obtained composite was confirmed by X-ray diffraction technique (XRD); 2) The structure and morphology of LTO and Si molecules were observed and studied with Scanning Electron Microscopy (SEM). [ABSTRACT FROM AUTHOR]

Abstract Li 4 Ti 5 O 12 (LTO) with a spinel structure is attractive as a promising anode for lithium-ion batteries due to a high charge/discharge voltage versus Li/Li+ and almost no volumetric expansion with improved cycle performance. In this study, a sea urchin-like nanostructured LTO (F-LTO) was prepared in the presence of F-127 as a surfactant. The morphology and structure of the samples were confirmed using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) method. To investigate the electrochemical properties of the samples, charging/discharging analysis was performed for 1000 cycles at a high current density. F-LTO showed an improved capacity retention rate and a high average capacity compared to the LTO sample prepared in the absence of F-127. It was found that, when using the high-rate performance analysis at different charging/discharging current densities, the intercalation of Li+ ion to an electrode might be a crucial factor to reduce capacity and energy density. Due to its porous nanostructure with high specific area, F-LTO showed low polarization and improved kinetic properties, resulting in enhanced LIB performance including high energy density and cycling properties. Graphical abstract Image 1 Highlights • A novel Li 4 Ti 5 O 12 nanostructure was synthesized using F-127 as a surfactant. • F-LTO exhibited a sea urchin-like nanostructure with a high surface area. • F-LTO facilitated an efficient contact between the electrode and electrolyte. • F-LTO showed low polarization and improved kinetic properties. • F-LTO exhibited the high rate cycling properties in LIBs. [ABSTRACT FROM AUTHOR]

Li 4-x Mg x Ti 5 O 12 (0 ≦ X ≦ 0.2) anode material was synthesized by a solid-state method using Li 2 CO 3 , MgO and anatase TiO 2 . The effects of Mg element doping on the crystal structure, phase composition, morphology and electrochemical properties of Li 4-x Mg x Ti 5 O 12 were investigated by XRD, SEM and EDX. The electrochemical properties of Li 4-x Mg x Ti 5 O 12 were characterized through Cyclic voltammetry and AC impedance experiments. The results indicated that when x = 0.10, the resultants show better electrochemical performance in higher rates cycle stability and the polarization degree. The initial discharge capacity reaches 122.5 mAh/g at 2 C, and the discharge capacity still remains 119.3 mAh/g after 100 cycles. [ABSTRACT FROM AUTHOR]

Excellent rate performance of Li 4+x Ti 5 O 12 (0 < x < 3, LTO) electrodes results from mixed Li site occupancy and facile Li ion exchange at 8a and 16c sites. In this paper, we reveal that inter-particle connectivity within LTO electrodes affects 8a and 16c site occupancies upon discharge and impacts Li ion diffusion. LTO electrodes of the same primary crystal structure but of different grain boundary structures were prepared and they showed significantly different electrochemical performance. LTO electrodes with a percolated 3D structural network and bridged grain boundaries offered balanced 8a-16c occupancy, Li ion exchange at 8a and 16c sites upon discharge, high ionic conductivities, and good rate performance. While LTO electrodes with isolated clusters of particles showed strong rate dependence of 8a-16c occupancy, a lack of Li ion exchange at 8a and 16c sites, large over-potential, and substantial capacity decay upon fast charging. Bridged grain boundaries in LTO secondary particles facilitate apparent solid-solution process during electrochemical cycling by maintaining Li site exchange and thus enhance the rate performance of LTO electrodes. [ABSTRACT FROM AUTHOR]

Lithium titanates are used in various applications, such as anode materials for lithium intercalation (Li4Ti5O12) or breeding materials in fusion reactors (Li2TiO3). Here, we report the formation of nano-crystalline lithium titanates by a mechanochemical approach and present a deeper insight into their structural characteristics by X-ray diffraction (XRD) and solid-state NMR spectroscopy. The compounds were synthesized in a high-energy planetary ball mill with varying milling parameters and different grinding tools. NaCl type Li2TiO3 (α-Li2TiO3) was formed by dry milling of lithium hydroxide with titania (rutile or anatase) and by a milling induced structure transformation of monoclinic β-Li2TiO3 or spinel type Li4Ti5O12. Heating of mechanochemical prepared α-Li2TiO3 induces a phase transformation to the monoclinic phase similar to hydrothermal reaction products, but a higher thermal stability was observed for the mechanochemical formed product. Microstructure and crystallographic structure were characterized by XRD via Rietveld analysis. Detailed phase analysis shows the formation of the cubic phase from the various educts. A set of two lattice parameters for α-Li2TiO3 was refined, depending on the presence of OH− during the milling process. An average crystallite size of less than 15 nm was observed for the mechanochemical generated products. The local Li environment detected by 6Li NMR revealed Li defects in the form of tetrahedral instead of octahedral site occupation. Subsequent adjustment of the structural model for Rietveld refinement leads to better fits, supporting this interpretation.

Pristine and carbon-coated Li 4 Ti 5 O 12 nanosheets are synthesized by a hydrothermal process, followed by calcination at 750 °C for 10 h. The structural properties of the as-prepared composites are characterized systematically by X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and N 2 adsorption–desorption analysis, respectively. Electrochemical lithium insertion/extraction performances are evaluated by the galvanostatic charge/discharge tests, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV), respectively. In comparison, Li 4 Ti 5 O 12 @C exhibits higher specific capacity, better rate capability and capacity retention than the pristine Li 4 Ti 5 O 12 . Analysis from the electrochemical measurements indicates that the enhanced electrochemical performances Li 4 Ti 5 O 12 @C might be attributed to the shorter Li-ion diffusion distance, lower charge-transfer resistance, better electrode kinetics and lower activation energy as a result of thinner nanosheet and the presence of carbon layer. [ABSTRACT FROM AUTHOR]

The influence of post-calcination treatment on spinel LiTiO anode material is extensively studied combining with a ball-milling-assisted rheological phase reaction method. The post-calcinated LiTiO shows a well distribution with expanded gaps between particles, which are beneficial for lithium ion mobility. Electrochemical results exhibit that the post-calcinated LiTiO delivers an improved specific capacity and rate capability. A high discharge capacity of 172.9 mAh g and a reversible charge capacity of 171.1 mAh g can be achieved at 1 C rate, which are very close to its theoretical capacity (175 mAh g). Even at the rate of 20 C, the post-calcinated LiTiO still delivers a quite high charge capacity of 124.5 mAh g after 50 cycles, which is much improved over that (43.9 mAh g) of the pure LiTiO without post-calcination treatment. This excellent electrochemical performance should be ascribed to the post-calcination process, which can greatly improve the lithium ion diffusion coefficient and further enhance the electrochemical kinetics significantly. [ABSTRACT FROM AUTHOR]

A new type of non-aqueous redox couple without carbon additives for flow batteries is proposed and the target anolyte chemistry is demonstrated. The so-called “Solid Dispersion Redox Couple” incorporates solid electroactive materials dispersed in organic lithium-ion battery electrolyte as its flowing suspension. In this work, a unique and systematic characterization approach has been used to study the flow battery redox couple in half cell demonstrations relative to a lithium electrode. An electrolyte laden with Li 4 Ti 5 O 12 (LTO) has been characterized in multiple specially designed lithium half cell configurations. The flow battery redox couple described in this report has relatively low viscosity, especially in comparison to other flow batteries with solid active materials. The lack of carbon additive allows characterization of the electrochemical properties of the electroactive material in flow without the complication of conductive additives and unambiguous observation of the electrorheological coupling in these dispersed particle systems. [ABSTRACT FROM AUTHOR]

The rate capability of a Li 4 Ti 5 O 12 (LTO)-based anode in a lithium ion battery can be easily improved by electron beam (EB) irradiation without the need for complicated synthetic procedures. The electrode prepared with EB-irradiated LTO at a 50 kGy dose has an enhanced rate capability while retaining a discharge capacity of 100 mAh g −1 , even at the 20 C-rate. The effect of EB irradiation on the properties of the anode materials (i.e., LTO, poly(vinylidene fluoride) (PVDF), super P carbon) is examined in detail through systematic experiments. Both LTO and PVDF are affected by EB irradiation and dependent on the exposed electron dose, but super P is affected negligibly. EB irradiation partially reduces LTO with forming Ti x+ (2 < x < 4) which is attributed to the enhanced electrical conductivity. EB irradiation causes dehydrofluorination and cross-linking in PVDF, resulting in the formation of carbon–carbon double bonds. The conjugated structure of PVDF is formed by the further dehydrofluorination during mixing with LTO via ball-milling, and this is accelerated in the presence of EB-PVDF. This conjugated structure enhances the electrical conductivity and is responsible for the improved rate capability. [ABSTRACT FROM AUTHOR]

Highly-crystalline gadolinium doped and carbon-coated ultrathin Li 4 Ti 5 O 12 (LTO) nanosheets (denoted as LTO-Gd-C) as an anode material for Li-ion batteries (LIBs) are synthesized on large scale by controlling the amount of carbon precursor in the topotactic transformation of layered ultrathin Li 1.81 H 0.19 Ti 2 O 5 ·xH 2 O (H-LTO) nanosheets at 700 °C. The characterizations of structure and morphology reveal that the gadolinium doped and carbon-coated ultrathin LTO nanosheets have high crystallinity with a thickness of about 10 nm. Gadolinium doping allows the spinel LTO products to be stabilized, thereby preserving the precursor's sheet morphology and single crystal structure. Carbon encapsulation serves dual functions by restraining crystal growth of the LTO primary nanoparticles in the LTO-Gd-C nanosheets and decreasing the external electron transport resistance. Owing to the synergistic effects rendered by ultrathin nanosheets with high crystallinity, gadolinium doping and carbon coating, the developed ultrathin LTO nanosheets possess excellent specific capacity, cycling performance, and rate capability compared with reference materials, when evaluated as an anode material for lithium ion batteries (LIBs). The simple and effective strategy encompassing nanoscale morphological engineering, surface modification, and doping improves the performance of LTO-based anode materials for high energy density and high power LIBs applied in large scale energy storage. [ABSTRACT FROM AUTHOR]

Electrochemical quartz crystal microbalance (EQCM) measurement is conducted with a Li 4 Ti 5 O 12 (lithium titanium oxide, LTO)-coated quartz crystal electrode in a carbonate electrolyte (ethylene carbonate + dimethyl carbonate; 50: 50 vol%) containing 1 M LiPF 6 . I n-situ monitoring of the mass change during the charge and discharge of the LTO electrode can be achieved quantitatively because of the “zero-strain” property of LTO with Li + insertion and the probably low reactivity between LTO and the electrolyte. The local changes of viscosity and density of the electrolyte contacting the LTO electrode are detected via the resonance resistance of the quartz crystal electrode, suggesting the local concentrations of Li + and counter anion changed significantly during insertion and extraction of Li + in the organic electrolyte. [ABSTRACT FROM AUTHOR]

Ethanol is added as a dispersing agent in the slurry preparation step for lithium-ion batteries, in which lithium titanium oxide (Li 4 Ti 5 O 12 , LTO) and conductive carbon (Super P) are dispersed into an aqueous solution of polymer binder (polyacrylic acid). The addition of ethanol suppresses the agglomeration of conductive carbon particles enabling homogeneous mixing of the electrode ingredients in the slurry, which eventually yields a uniform distribution of the LTO and Super P particles in the composite electrodes. Because of the reinforced electrically conductive network formed between the LTO and Super P, the electrode resistance becomes smaller, and thus, a high rate capability is achieved; the capacity of the LTO at 30 C is 73% of that observed at 0.5 C. [ABSTRACT FROM AUTHOR]

A series of Tantalum-doped lithium titanate (Ta-doped Li 4 Ti 5 O 12 ) samples have been successfully synthesized by one step solid-state method using TiO 2 , Li 2 CO 3 , and Ta 2 O 5 as raw materials. The Li 4 Ti 5 O 12 with only 0.1 at% Ta doping (Li 4 Ti 4.995 Ta 0.005 O 12 ) exhibits higher rate capability and better cyclic stability than the pristine Li 4 Ti 5 O 12 . Li 4 Ti 4.995 Ta 0.005 O 12 could deliver 95.1 mAh g −1 at 10C with much lower overpotential (216.1 mV) while the pristine Li 4 Ti 5 O 12 delivers only 50.4 mAh g −1 at 10C with higher overpotential of 392.2 mV. As indicated by XRD, HRTEM and electrochemical characterizations, Ta doping in Li 4 Ti 5 O 12 would enlarge the lattice parameter of the Li 4 Ti 5 O 12 , and facilitate the Li + diffusion during the charge/discharge process. In addition, the higher charge compensation of the stoichiometric reduction of Ti 4+ to Ti 3+ by introducing Ta increases the electronic conductivity of Li 4 Ti 5 O 12 . The improved ionic conductivity and electronic conductivity are beneficial to the electrochemical performance of Li 4 Ti 5 O 12 . As a result, Ta doping is a new strategy for enhancing the electrochemical performance of Li 4 Ti 5 O 12 . [ABSTRACT FROM AUTHOR]

Micro-sized Li 4 Ti 5−x Bi x O 12 (0 ≤ x ≤ 0.15) materials are synthesized using a simple solid state method in air. The structural, morphological, and electrochemical characteristics of Bi-doped lithium titanates and pristine samples are methodically analyzed by X-ray diffraction (XRD), Raman spectroscopy, field emission-scanning electron microscopy (FE-SEM), and electrochemical impedance spectroscopy (EIS). The XRD and Raman spectroscopy results demonstrate that bismuth-doping do not alter the spinel structure and good crystalline materials are synthesized. The FE-SEM images show that all samples possess the same morphological characteristics, with a particle size distribution of 0.5–1 μm. The electrochemical cycling testing reveals that the Li 4 Ti 4.9 Bi 0.10 O 12 sample exhibits discharge capacities of 205.4 mAh g −1 , 160.8 mAh g −1 , and 135.4 mAh g −1 after 50 cycles at 1C, 5C, and 10C-rates, respectively. The differential capacity curves suggest that the Li 4 Ti 4.9 Bi 0.10 O 12 sample has a weaker polarization effect than the other samples. The EIS measurements imply that the Li 4 Ti 4.9 Bi 0.10 O 12 sample possesses a high electronic conductivity and lithium ion diffusivity, which demonstrate that this new Li 4 Ti 4.9 Bi 0.10 O 12 material would be a good candidate as an anode for lithium ion batteries. [ABSTRACT FROM AUTHOR]

A novel composite of highly-crystalline ultrathin Li 4 Ti 5 O 12 (LTO) nanosheets and Ag nanocrystals (denoted as LTO NSs/Ag) as an anode material for Li-ion batteries (LIBs) is prepared by hydrothermal synthesis, post calcination and electroless deposition. The characterizations of structure and morphology reveal that the LTO nanosheets have single-crystal nature with a thickness of about 10 nm and highly dispersed Ag nanocrystals have an average diameter of 5.8 nm. The designed LTO NSs/Ag composite takes advantage of both components, thereby providing large contact area between the electrolyte and electrode, low polarization of voltage difference, high electrical conductivity and lithium ion diffusion coefficient during electrochemical processes. The evaluation of its electrochemical performance demonstrates that the prepared LTO NSs/Ag composite has superior lithium storage performance. More importantly, this unique composite has an ability to deliver high reversible capacities with superlative cyclic capacity retention at different current rates, and exhibit excellent high-rate performance at a current rate as high as 30 C. Our results improve the current performance of LTO based anode material for LIBs. [ABSTRACT FROM AUTHOR]

Rosin, which is an extract of pine trees, is used as an eco-friendly binder additive to a conventional solvent-based binder, polyvinylidene fluoride (PVdF). The composite binder system is used to evaluate the performance of the Li 4 Ti 5 O 12 (LTO) electrodes using a range of physical and electrochemical characterization techniques. The addition of rosin decreases the crystallinity of PVdF, disperses the conducting agent and binder well, and ultimately leads to an increase in the diffusivity and cyclic capacity of lithium ions. When the amount of rosin additive to the PVdF binder is 40 wt%, the LTO electrode exhibits the highest cyclic capacity and diffusivity; of 164 mAh g −1 at the 110th cycle and 4.28 × 10 −10 cm 2 s −1 , respectively. [ABSTRACT FROM AUTHOR]

Lithium titanium oxide (Li 4 Ti 5 O 12 ) is a promising anode material, owing to its superior safety and reliability. However, the main challenge of Li 4 Ti 5 O 12 is the low material conductivity which restricts its electrochemical performance. In order to use Li 4 Ti 5 O 12 in practical sodium-ion batteries, copper-doped Li 4 Ti 5 O 12 (Li 4− x Cu x Ti 5 O 12 , x = 0, 0.05, 0.1) nanoparticles were prepared to enhance the electronic conductivity. Copper-doped Li 4 Ti 5 O 12 nanoparticles were then embedded in continuous carbon nanofibers (CNFs), which gave rise to fast electron transfer along the fiber direction. After copper-doping and CNF embedding, the resultant copper-doped Li 4 Ti 5 O 12 /CNFs achieved excellent reversible capacity (158.1 mAh g −1 ) at 30 mA g −1 , high coulombic efficiency (99.87%), and good capacity retention (91%) after 150 cycles. In addition, copper-doped Li 4 Ti 5 O 12 /CNFs also exhibited good rate capability. It is, therefore, demonstrated that copper-doped Li 4 Ti 5 O 12 /CNFs are promising anode candidate. [ABSTRACT FROM AUTHOR]

A continuous supercritical fluid process is adopted for the synthesis of lithium titanium oxide (Li 4 Ti 5 O 12 , LTO) nanoparticles for applications in lithium ion batteries. The effect of various synthetic conditions, including concentration, residence time, precursor ratios, and supercritical fluids on the phase purity and particle properties are examined. The as-synthesized samples in supercritical water (scH 2 O) or in supercritical methanol (scMeOH) exhibit nanoparticles with sizes of 4–10 nm, but retain an amount of Li of 6.8–8.6 mol.% less than that of the stoichiometric Li content in LTO. The deficient amount of Li is added and calcined in an air or H 2 /Ar flow at 600 °C. The calcined LTO exhibits phase-pure LTO with high crystallinity. The air-calcined LTO synthesized in scH 2 O exhibits an initial discharge capacity of 174.2 mAh g −1 at 0.1 C, good rate performance of up to 4 C (133.4 mAh g −1 ), and excellent long-term cyclability for up to 200 cycles. The H 2 /Ar-calcined LTO synthesized in scMeOH exhibits an ultrathin and uniform carbon layer on the nanosized LTO with a thickness of 0.5–1 nm. It thus shows much better high-rate performance for charge–discharge rates of above 8 C compared to the air-calcined LTO synthesized in scH 2 O. [ABSTRACT FROM AUTHOR]

Abstract: The cells applied with a three-dimensionally (3D) patterned Li4Ti5O12 (LTO) electrode showed good performance as a rechargeable lithium-ion battery. The 3D-patterned electrode was fabricated with a printing apparatus and has many lined patterns with a high aspect ratio standing in line on a current collector. The cell using 3D-patterned electrode showed much better rate capability than that using a conventional flat electrode. In this research, cyclic voltammetry was carried out to investigate the mechanism realizing the high rates of charging and discharging in 3D-patterned electrode. Various types of line patterns were fabricated for 3D electrode by using LTO electrode slurry, and the influences of basic specifications of electrode structure (the space between two neighboring electrode lines, the height and width of electrode) on the charge and discharge characteristics were evaluated to optimize the electrode pattern. In addition, the electrode performance was discussed from the viewpoints of ohmic resistance and charge-transfer resistance of the cells with 3D-patterned and conventional flat electrodes. [Copyright &y& Elsevier]

Abstract: In this study, the application of neutron powder diffraction on studying the time-resolved structural evolution of a cell comprised with LiNi0.5Mn1.5O4 cathode and Li4Ti5O12 anode during charge–discharge cycling is demonstrated. As expected, the lattices of the LiNi0.5Mn1.5O4 cathode and the Li4Ti5O12 anode in the cell are found to simultaneously contract during charging and expand during discharging. It is found that for the LiNi0.5Mn1.5O4 cathode a solid-solution reaction is associated with the lattice change and the Ni2+/Ni3+ redox couple between 3.06 and 3.16 V (vs. Li4Ti5O12), and a two-phase reaction between Li x Ni0.5Mn1.5O4 and Ni0.25Mn0.75O2 is corresponding to the Ni3+/Ni4+ redox couple at voltage higher than 3.22 V (vs. Li4Ti5O12) without a corresponding change in lattice. The oxidation states of the metals in the electrodes are determined by tracking the associated change in the oxygen position. In addition, the Ti oxidation state is correlated to the intensity of the Li4Ti5O12 222 reflection at the anode, and the determined oxidation state of the Ni is correlated to the lithium occupancy within the cathode. Furthermore, the small volume changes of the cathode and the anode upon cycling suggest that the cell chemistry is favorable for practical applications. [Copyright &y& Elsevier]

Abstract: The spinel Li4Ti5O12 has been doped by Na for the purpose of improving its cycle performance as an anode. The lattice parameter of Li4Ti5O12 increases due to the Na doping. SEM shows that all materials are well crystallized with a particle size in the range of 400–600 nm. The pristine Li4Ti5O12 sample has a bigger particle size than that of Na-doped samples. Although the doping does not change the crystallographic structure of Li4Ti5O12, they exhibit better cyclability at high charge–discharge rate compared with pristine Li4Ti5O12. Li3.85Na0.15Ti5O12 gives the best cycling performance, only 11.1% loss of capacity after 80 cycles at 2 C charge–discharge rate. Na-doped Li4Ti5O12 exhibits lower potential separation, indicating faster electron transfer kinetics and cycling reversibility. Electrochemical impedance spectroscopy demonstrates that the improved performance of the Na-doped Li4Ti5O12 is due to a small decrease in the charge transfer resistance, indicating high electrochemical activity during cycling. The excellent cycling and safety performance of the Na-doped Li4Ti5O12 electrodes are found to be due to the significantly increased ionic and electronic conductivity. Since fast charge–discharge performance is an important factor that needs to be considered in fabricating power batteries in industry, the Na-doped Li4Ti5O12 materials moves closer to real and large scale applications. [Copyright &y& Elsevier]

Li4Ti5O12 and Al3+ doped Li(4−x/3)Al x Ti(5−2x/3)O12 (x = 0, 0.01, 0.05, 0.1, 0.15, 0.2) are synthesized at 750, 850, 950 °C via solid state reaction using TiO2-rutile, Li2CO3 and Al2O3 as precursors. The samples at 850, 950 °C have better phase purity than those at 750 °C. The preliminary charge–discharge cycling test of undoped and Al3+ doped Li4Ti5O12 reveals that the electrochemical performance of the electrode prepared at 850 °C is better than that at 750, 950 °C. Therefore, the optimum calcination temperature is found to be 850 °C. Li(4−x/3)Al x Ti(5−2x/3)O12 (x = 0.01, 0.05, 0.1), which is the low Al-doped sample, exhibits a higher discharge capacity and rate performance than the high Al-doped Li4Ti5O12 (x = 0.15, 0.2) sample. The first discharge capacities at 0.2, 0.5, and 1 C are 174.4, 161.9, and 153.8mAhg−1, respectively for Li(4−x/3)Al x Ti(5−2x/3)O12 (x = 0.1). These values are similar to those of Li(4−x/3)Al x Ti(5−2x/3)O12 (x = 0.01, 0.05). The capacity retention ratio of Li(4−x/3)Al x Ti(5−2x/3)O12 (x = 0.01, 0.05, 0.1) is over 99.3% after 30 cycles. The capacity increase and good rate performance in the optimum Al-doped Li4Ti5O12 are discussed in relation to the stability of the spinel structure and the resulting ease of lithium insertion. [ABSTRACT FROM AUTHOR]

Abstract: In an effort to improve the rate-capability of Li4Ti5O12 anode material, a dual-phase composite Li4Ti5O12–TiO2 is in situ prepared via a solvothermal route. The Li4Ti5O12–TiO2 composite shows higher reversible capacity and better rate-capability compared to single phase Li4Ti5O12. The TiO2 can decrease significantly the particle size of Li4Ti5O12–TiO2 powders due to a steric hindrance effect, which thereby shortens the lithium ion diffusion distance and enhances the electrode reaction. Meanwhile, anatase TiO2 can contribute some capacity to the Li4Ti5O12–TiO2 electrode. Coating the Li4Ti5O12–TiO2 composite with carbon (∼2.5 wt.%) can further improve the rate-capability of Li4Ti5O12–TiO2 electrode, a reversible capacity of ∼140 mA h g−1 is maintained after 100 cycles at 5 C. [Copyright &y& Elsevier]

Abstract: Li4Ti5O12 (LTO) thin films are deposited by dc-ion beam sputtering at different oxygen partial pressures and different substrate temperatures. In order to investigate, how these two parameters influence the atomic structure, the specimens are characterized by X-ray diffraction and transmission electron microscopy. Electrochemical characterization of the films is done by cyclic voltammetry and chrono-potentiometry. To determine an averaged chemical diffusion coefficient of lithium, a method is developed, evaluating c-rate tests. The results obtained by this method are compared to results obtained by the well established galvanostatic intermittent titration technique (GITT), which is used to determine a concentration dependent diffusion coefficient of lithium in LTO. [Copyright &y& Elsevier]

Abstract: A micro-sized particle Li4Ti5−x La x O12 (0 ≤ x ≤ 0.2) material has been synthesized by a simple solid-state method at air. The obtained Li4Ti5−x La x O12 materials are Li3x La2/3−x TiO3 (LLTO)–Li4Ti5O12 (LTO) solid solution, and well crystallized with a particle size in the range of 1–2 μm. The electronic conductivity and lithium diffusion coefficient of La-modified LTO (Li4Ti4.95La0.05O12) are improved because LLTO exhibits a high ionic conductivity during Li+ extraction. Li4Ti4.95La0.05O12 material shows discharge capacities of more than 206 and 197 mAh g−1 after 100 cycles at 1 C and 3 C charge–discharge rates, respectively. Especially, in rate performance, the Li4Ti5−x La x O12 (x = 0.1, 0.2) samples maintain capacity of about 181 mAh g−1 until 5 C rates after 200 cycles, while the pure LTO sample shows a severe capacity decline at corresponding rate. These results suggest that La modifying is an effective way to improve the chemical stability of the electrode in contact with the electrolyte and improve their cyclability and rate capability during long term cycling. Since high rate performance is an important factor that needs to be considered in fabricating power batteries in industry, the La-modified LTO moves closer to real and large-scale applications. [Copyright &y& Elsevier]

Abstract: A LiCoMnO4 (5V spinel) material has been synthesized by annealing a sol–gel precursor utilizing lithium acetate, cobalt acetate, manganese acetate, and citric acid. The as-prepared sample has been determined to be LiCo1.09Mn0.91O4 via inductive coupled plasma-atomic emission spectroscopy. The deviation of the molar ratio of Co/Mn from 1:1 is designed to minimize the amount of LiMn2O4 impurity in our sample. The produced spinel material possesses an initial discharge capacity of 87.1mAhg−1 with two voltage plateaus at 5.1 and 4.9V. The LiCo1.09Mn0.91O4 cathode has been assembled with a Li4Ti5O12 anode to form a full-cell which delivered a discharge capacity of 131.2mAhg−1, centered at 3.2V. It is of great interest that despite the low coulombic efficiency of the full-cell, it shows good cyclic performance. In addition, The LiCo1.09Mn0.91O4/Li4Ti5O12 cell shows an excellent rate capability, delivering a capacity of 84.2mAhg−1, corresponding to a high power density of 4.70kWkg−1 at the current density of 1700mAg−1. [Copyright &y& Elsevier]

Abstract: A theoretical study of the structural, elastic and electronic properties of spinel LiTi2O4 anode has been performed by density functional theory (DFT) plane-wave pseudopotential method. The independent elastic constants, shear modulus (G), bulk modulus (B), and Young''s modulus (E) are evaluated, respectively. The results suggest that cubic LiTi2O4 is mechanically stable. The G/B ratio of 0.584 indicates the ductility of LiTi2O4 is good. The electron density difference of LiTi2O4 shows that the O2p orbits overlap effectively with Ti3d ones, confirming the formations of strong covalent bonds between them, while Li is fully ionized in the lattice. The formation enthalpy for LiTi2O4 is calculated to be −2070.723±1.6kJmol−1. The strong covalent bonds between O and Ti atoms are not only responsible for the excellent mechanical stabilities but also very crucial for the thermodynamic stability of LiTi2O4 compound. Furthermore, in Li2Ti2O4 compound, the full occupation of 16(c) sites by Li+ not only leads to a smaller C 12 value but also leads to a much larger C 44 one. Therefore, the plasticity and ductility of the Li2Ti2O4 become poor in comparison to LiTi2O4, while the thermodynamic stability of Li2Ti2O4 can be further improved after the Li+ intercalation of LiTi2O4. [Copyright &y& Elsevier]

Abstract: Lithium titanium oxide (LTO) with a ramsdellite structure is an advantageous anode for lithium ion secondary batteries, because of its positive potential, which is beneficial for safety reasons. In addition, compared with other titanate anodes, it has a superior theoretical capacity of 321mAhg−1, which is close to the capacity of a practical carbonaceous anode. Our study showed that this ramsdellite-type LTO had a high discharge capacity that is stable at 250mAhg−1 at a current density of 1mAcm−2. However, this high capacity is only achieved by employing as-synthesized ramsdellite LTO powder. When the same powder was stored and the same evaluation was carried out, the resulting capacity was 200mAhg−1, which is lower than the capacity of as-synthesized powder. An annealing applied to the ramsdellite LTO powder appeared to restore the capacity loss after storage. Annealing at 250°C for 5h produced the best performance, which was even better than that obtained using the as-synthesized ramsdellite LTO powder. Moreover, we investigated the surface property of ramsdellite LTO and found that the presence of a carbon derivative is apparently responsible for blocking the Li ions insertion/extraction, and thus reducing the capacity. [Copyright &y& Elsevier]