Lithium Titanate Oxide Research Articles

Synthesis and characterization of a new family of aryl-trifluoromethanesulfonylimide Li-Salts for Li-ion batteries and beyond

The battery energy-storage industry is evolving rapidly so new battery components are needed with high stability and improved energy density, as well as enhanced safety. In this paper, results on new salts, safer degradation and good electrochemical performances are reported. Four organic anions for Li-salts were synthesized and their conductivity, viscosity and electrochemical potential window in EC/DEC (3/7) solutions were examined. These salts have high thermal stability and safer degradation products (compared to LiPF6 and Li-TFSI), which were identified by TGA-MS. Cyclic voltammetry measurements showed their electrochemical window and oxidation limits were at least 4.3 and 4.5 V vs Li/Li+ using a platinum and high surface area carbon material working electrode, respectively. The salts passivated the common aluminum current collector at 4.4 V vs Li/Li+ and without corrosion. The properties of one Li salts were evaluated in half cell configuration as a model system using lithium iron phosphate (LFP), lithium titanate oxide (LTO) and graphite as electrodes. The performance of the salt showed promising behavior in the model system, compared to benchmark salts such as LiPF6 and Li-TFSI.

Polypeptides for Bio-Tethering and Self-Assembly of Lithium Ion Battery Electrodes

The goal of this research is to isolate multifunctional polypeptide sequences for bio-tethering electrode material and carbon nanotubes in order to decrease internal resistance in lithium ion batteries thereby improving their performance. Phage display is the key technique performed in our research. This involves the use of an M13 bacteriophage library which has been genetically engineered to express a randomized polypeptide sequence of 12 amino acids on the pIII minor coat protein. To perform phage display a library of bacteriophage expressing these randomized polypeptide sequences were mixed with electroactive materials lithium manganese oxide(LMO) and lithium titanate oxide(LTO). Samples were then shaken and elution of bound phage was performed by adding increasing concentrations of surfactant in order to isolate phage that stick tightly to the electroactive materials. The supernatants from each of the successive wash rounds were saved and titered. The strongest elutions represent bacteriophage expressing a peptide sequence with high binding affinity for the tested materials. Isolated colonies produced from single bacteriophage were then sequenced. Results have currently been obtained for LTO and LMO binding peptides. As research progresses we will refine and isolate other peptides that bind specifically to electroactive materials as well as conductive carbon nanotubes, current collectors, and separator materials. Binding studies will be performed to characterize the amino acid sequence as well as to improve peptide-material interactions, such that electrode binders may be replaced by these peptides. These peptides will then be used to generate an aqueous, self-assembling, lithium ion battery electrode.This work was funded by the UMBC Department of Chemistry and Biochemistry.

Compatibility of Aprotic Electrolytes with Negative Electrode Materials in Lithium-Ion Batteries

This short research presents an introduction to the fire safety of Lithium-ion batteries. Nowadays, as the most weak part of aprotic battery is its aprotic electrolyte. The aprotic electrolyte (commonly the mixture of aprotic solvents) that is used in Lithium-ion batteries have got low flash point with poor thermal stability. This paper describes using sulfolane as an aprotic solvent in Lithium-ion battery. Measurements were focused on performance, cyclability and stability of aprotic electrolyte with relation of graphite material as a negative electrode. Like a possible substitution of graphite, the LTO material was used and tested. Lithium Titanate Oxide (LTO) seems to be promising negative electrode material for Lithium-ion batteries.

A High Areal Capacity Flexible Lithium‐Ion Battery with a Strain‐Compliant Design

Early demonstrations of wearable devices have driven interest in flexible lithium‐ion batteries. Previous demonstrations of flexible lithium‐ion batteries trade off between low areal capacity, poor mechanical flexibility and/or high thickness of inactive components. Here, a reinforced electrode design is used to support the active layers of the battery and a freestanding carbon nanotube (CNT) layer is used as the current collector. The supported architecture helps to increase the areal capacity (mAh cm‐2) of the battery and improve the tensile strength and mechanical flexibility of the electrodes. Batteries based on lithium cobalt oxide and lithium titanate oxide shows excellent electrochemical and mechanical performance. The battery has an areal capacity of ≈1 mAh cm‐2 and a capacity retention of around 94% after cycling the battery for 450 cycles at a C/2 rate. The reinforced electrode has a tensile strength of ≈5.5–7.0 MPa and shows excellent capacity retention after repeatedly flexing to a bending radius ranging from 45 to 10 mm. The relationships between mechanical flexing, electrochemical performance, and mechanical integrity of the battery are studied using electrochemical cycling, electron microscopy, and electrochemical impedance spectroscopy (EIS).

Impedance Growth with Lithium Titanate Based Cells; Understanding and Mitigation

SAFT has successfully applied Li-ion electrochemistry to defense, space, and commercial applications which require very high power. In fact, by optimizing both the electrochemical and electro-mechanical cell design, Saft has developed a range of Li-ion products that can deliver up to 10 kW/kg of power for 10 seconds and over 30 kW/kg of power for a fraction of a second. There are, however, still inherent limitations for high power applications with traditional Li-ion chemistry. Particularly, even with an optimized cell design, cycle life can be limited for applications which require very rapid charging due to both Lithium plating and electrolyte decomposition on the graphitic negative electrode. Lithium titanate oxide (LTO), due to operation above both the lithium plating and solvent reduction potentials, minimizes these phenomenon and can potentially provide extremely long cycle life. Saft is working, with DOE/USABC funding, to industrialize LTO based technology for high power applications. Results will be presented including power capability, high temperature impedance growth, capacity fade, and gas generation. In particular, impedance growth, which is a major obstacle to large scale use of LTO, will be discussed including mechanistic understanding and methods of mitigation.

Field Experience from Li-Ion Bess Delivering Primary Frequency Regulation in the Danish Energy Market

Introduction Li-ion batteries, after dominating the sector of portable electronics, are currently entering into a new market of the short and medium time stationary energy storage applications. Energy storage systems (ESSs) are considered to play a key role in the integration of the renewables in the grids of the high wind energy penetration and to participate in the future grids ancillary services. Nevertheless, they are currently missing market mechanisms and incentives for ESSs, which could attract potential investors and be economic viable.This paper will present results and one year field experience gained from operation of the 1.6MW /0.4MWh Li-ion battery energy storage (BESS) demonstrator used for providing primary frequency regulation on the Danish market. Moreover, the results from the periodic check-ups of the Li-ion BESS performance degradation and ageing will be presented. System description The ESS, located in Western Denmark, is composed of two Li-ion battery containers connected in parallel, through the power converter system, to the MV bus of the transformer, as illustrated in Fig. 1. The first ESS (ESS1) is based on lithium iron phosphate (LiFePO4/C) battery cells (3.3V/2.3Ah) and it can deliver 0.4 MW/ 0.1MWh. The second ESS (ESS2) is based on lithium titanate oxide (LMO2/Li4Ti5O12) battery cells (2.3V/60Ah) and it can deliver 1.2 MW/ 0.3MWh. Lifetime Periodical reference performance tests of the both Li-ion BESSs were performed for a period of one year in order to determine and analyze the performance degradation, which is caused by delivering the PFR service. The reference performance tests consists of capacity test, hybrid pulse power characterization (HPPC test) and electrochemical impedance spectroscopy measurements performed on some battery modules removed from the BESS for a duration of the reference performance tests. Economic analyses High prices of the primary frequency regulation service, low BESS utilization factor and low depth of discharge cycles (Fig. 2) are making this service potentially economic viable on the Danish market. Thus, economic calculations will be provided including revenues, predicted lifetime of the BESSs and auxiliary power consumption (cooling systems of the BESS, cooling of the converter, etc).

Self-supported Li4Ti5O12 nanosheet arrays for lithium ion batteries with excellent rate capability and ultralong cycle life

Facile fabrication of well-aligned Li4Ti5O12 (LTO) nanosheet arrays grown directly on conductive Ti foil was achieved by hydrothermal growth in LiOH solution. The reaction between Ti foil and LiOH led to the growth of vertically aligned, rectangular lithium titanate oxide hydrate (H-LTO) nanosheet arrays, which could be converted into LTO nanosheet arrays through topotactic transformation via thermal decomposition. An appropriate LiOH concentration was essential for the formation of densely aligned H-LTO nanosheet arrays on the substrate. It was proposed that the formation of the H-LTO nanosheet arrays was through kinetics-controlled growth during the hydrothermal metal corrosion process. When used as a binder-free anode for LIBs, the self-supported LTO nanosheet arrays standing on Ti foil exhibited an excellent rate capability (a reversible capacity of 163 mA h g−1 and 78 mA h g−1 at 20 C and 200 C, respectively) and an outstanding cycling performance (a capacity retention of 124 mA h g−1 after 3000 cycles at 50 C). Furthermore, a flexible lithium ion battery, which could be fully recharged within 30 s and was able to light an LED, was assembled by using the LTO nanosheet arrays as the anode.

Rechargeable Energy Storage Systems for Plug-in Hybrid Electric Vehicles—Assessment of Electrical Characteristics

In this paper, the performances of various lithium-ion chemistries for use in plug-in hybrid electric vehicles have been investigated and compared to several other rechargeable energy storage systems technologies such as lead-acid, nickel-metal hydride and electrical-double layer capacitors. The analysis has shown the beneficial properties of lithium-ion in the terms of energy density, power density and rate capabilities. Particularly, the nickel manganese cobalt oxide cathode stands out with the high energy density up to 160 Wh/kg, compared to 70–110, 90 and 71 Wh/kg for lithium iron phosphate cathode, lithium nickel cobalt aluminum cathode and, lithium titanate oxide anode battery cells, respectively. These values are considerably higher than the lead-acid (23–28 Wh/kg) and nickel-metal hydride (44–53 Wh/kg) battery technologies. The dynamic discharge performance test shows that the energy efficiency of the lithium-ion batteries is significantly higher than the lead-acid and nickel-metal hydride technologies. The efficiency varies between 86% and 98%, with the best values obtained by pouch battery cells, ahead of cylindrical and prismatic battery design concepts. Also the power capacity of lithium-ion technology is superior compared to other technologies. The power density is in the range of 300–2400 W/kg against 200–400 and 90–120 W/kg for lead-acid and nickel-metal hydride, respectively. However, considering the influence of energy efficiency, the power density is in the range of 100–1150 W/kg. Lithium-ion batteries optimized for high energy are at the lower end of this range and are challenged to meet the United States Advanced Battery Consortium, SuperLIB and Massachusetts Institute of Technology goals. Their association with electric-double layer capacitors, which have low energy density (4–6 Wh/kg) but outstanding power capabilities, could be very interesting. The study of the rate capability of the lithium-ion batteries has allowed for a new state of charge estimation, encompassing all essential performance parameters. The rate capabilities tests are reflected by Peukert constants, which are significantly lower for lithium-ion batteries than for nickel-metal hydride and lead-acid. Furthermore, rate capabilities during charging have been investigated. Lithium-ion batteries are able to store about 80% of the capacity at current rate 2It, with high power cells accepting over 90%. At higher charging rates of 5It or more, the internal resistance impedes charge acceptance by high energy cells. The lithium titanate anode, due to its high surface area (100 m2/g compared to 3 m2/g for the graphite based anode) performs much better in this respect. The behavior of lithium-ion batteries has been investigated at different conditions. The analysis has leaded us to a new lithium ion battery model. This model will be compared to existing battery models in future research contributions.

Improving the high rate performance of Li4Ti5O12 through divalent zinc substitution

Microscale Li4Ti5−xZnxO12 (0 ≤ x ≤ 0.2) particles with high phase purity were synthesized by a simple solid-state reaction. The effect of the zinc doping on the physicochemical properties of Li4Ti5O12 (LTO) was extensively studied by TG-DSC, XRD, Raman spectroscopy, SEM, CV, EIS, and galvanostatic charge–discharge testing. The crystallization of lithium titanate oxide forms at about 750 °C. The lattice parameter of the Zn-doped LTO samples is slightly smaller than that for the pure LTO samples, and zinc doping does not change the basic Li4Ti5O12 structure. Even though the material has a particle size of 1–2 μm, Zn-doped LTO shows very high excellent capacity retention between 0 and 2.5 V. Especially, in rate performance, the Li4Ti4.8Zn0.2O12 sample maintains capacity of about 180 mAh g−1 until 5 C rates after 200 cycles, while the pure LTO sample shows severe capacity decline at corresponding rates. The reason for the high rate performance of Zn-doped LTO anode is ascertained to the diffusion coefficient (DLi) and reversible intercalation and deintercalation of lithium ion. The superior cycling performance and wide discharge voltage range, as well as simple synthesis route and low synthesis cost of the Zn-doped LTO are expected to show a potential commercial application.

Hydrothermal synthesis of layered Li1.81H0.19Ti2O5·xH2O nanosheets and their transformation to single-crystalline Li4Ti5O12 nanosheets as the anode materials for Li-ion batteries

Lithium titanate oxide hydrate (Li1.81H0.19Ti2O5·xH2O) nanosheets were prepared via simple hydrothermal treatment of the low cost tetrabutyl titanate in LiOH solution. The orthorhombic Li1.81H0.19Ti2O5·xH2O nanosheets with thickness less than 10 nm were single crystalline and grew along the (100) facet. Time-dependent experiments confirmed that the formation of Li1.81H0.19Ti2O5·xH2O nanosheets underwent a hydrolysis–Kirkendall effect–Ostwald ripening process. As these Li1.81H0.19Ti2O5·xH2O nanosheets calcined at 500 °C for 2 h, the Li4Ti5O12 nanosheets with thickness of 10–20 nm were synthesized. The Li4Ti5O12 nanosheets were single crystalline and grew along the (110) facet. As an anode material for rechargeable lithium-ion batteries, Li4Ti5O12 nanosheets delivered an initial discharge capacity of 183 mAh g−1 together with a discharge capacity of 160 mAh g−1 after 100 cycles at 1 C. The discharge capacity could reach up to 120 mAh g−1 even after 300 cycles at 10 C. The morphology of nanosheets with large BET value (155.5 m2 g−1) and the high lithium-ion diffusion coefficient (1.51 × 10−8 cm2 s−1) could be favorable for the enhanced high-rate performance.

Cation ordering and order–disorder phase transitionin Co-substituted Li4Ti5O12 spinels

In this paper we present the results of the synthesis, crystal structure investigations and in situ X-ray diffraction studies of the order–disorder phase transition in cobalt substituted lithium titanate oxide spinels, Li1.33xCo2–2xTi1+0.67xO4 (0 ≤ x ≤ 1). Depending on the chemical composition the samples crystallize in two space groups (S.G.): (0 ≤ x ≤ 0.40 and x = 1) and P4332 (0.50 ≤ x ≤ 0.875). Samples crystallizing in the S.G. P4332 are ordered spinels with a cation ordering of the 1–3 type at octahedral 4b and 12d sites. The cation ordering in octahedral sites is full in the sample with x = 0.75 (Li and Ti occupy 4b and 12d sites, respectively) and decreases for samples with higher/smaller x. Changes of the extinction conditions and nonlinearities in the concentration dependence of the lattice parameter in the regions 0.40 < x < 0.50 and 0.875 < x < 1 indicate changes of the crystal symmetry ( ⟷ P4332). The partially ordered spinel x = 0.50 has a convergent, reversible, order–disorder phase transition at TC = (1083 ± 10) K. Samples with x = 0.875 and 0.75 have an order–disorder phase transition out of our experimental ranges with TC(x = 0.875) < 973 K and TC(x = 0.75) > 1173 K. The mechanism of the phase transition is based on cation migration.