In Situ Gas Analysis of Li4Ti5O12Based Electrodes at Elevated Temperatures

Integrated with heat generating devices, a Li-ion battery (LIB) often operates at 20-40 o C higher than the ordinary working temperature. Although macroscopic investigation of thermal contribution has shown significant reduction on LIB performance, the molecular-level structural and chemical origin of battery aging in mild thermal environment has not been elucidated. Based on the combined experiments of electrochemical measurements, Cs-corrected electron microscopy, and in situ analyses, we herein provide operando structural and chemical insights on how mild thermal environment affects the overall battery performance, using anatase TiO 2 as a model intercalation compound. Interestingly, mild thermal condition induces excess lithium intercalation even at near-ambient temperature (45 o C), which does not occur in the ordinary working temperature. The anomalous intercalation enables excess lithium storage in the first few cycles but exert severe intra-crystal stress, consequently cracking the crystal that leads to battery aging. Importantly, this mild thermal effect is accumulated upon cycling, resulting in irreversible capacity loss even after the thermal condition is removed. Battery aging at high working temperature is universal in nearly all intercalation compounds, and therefore it is significant to understand how thermal condition contributes to battery aging for designing intercalation compounds for advanced battery electrode materials.

Chemistry - A European Journal, 2012

National Science Review, 2018

Lithium titanium oxide (Li4Ti5O12, LTO), a ‘zero-strain’ anode material for lithium-ion batteries, exhibits excellent cycling performance. However, its poor conductivity highly limits its applications. Here, the structural stability and conductivity of LTO were studied using in situ high-pressure measurements and first-principles calculations. LTO underwent a pressure-induced amorphization (PIA) at 26.9 GPa. The impedance spectroscopy revealed that the conductivity of LTO improved significantly after amorphization and that the conductivity of decompressed amorphous LTO increased by an order of magnitude compared with its starting phase. Furthermore, our calculations demonstrated that the different compressibility of the LiO6 and TiO6 octahedra in the structure was crucial for the PIA. The amorphous phase promotes Li+ diffusion and enhances its ionic conductivity by providing defects for ion migration. Our results not only provide an insight into the pressure depended structural prop...

Energy & Environmental Science, 2013

Journal of Power Sources, 2019

This work investigates the impact of electrochemical reactions and products on discharge capacity and cycling stability with electrolytes based on two common solvents-tetraethylene glycol dimethyl ether (TEGDME) and dimethyl sulfoxide (DMSO). Although the DMSO-based electrolyte exhibits better initial electrochemical properties compared to that based on TEGDME, e.g., higher discharge capacity and potential, the use of TEGDME results in a significantly better cycling stability. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) investigations of the gas diffusion electrodes (GDE) after first discharge reveal a considerable difference in discharge product morphology. With DMSO as solvent one high-potential reduction process leads to the formation of crystalline lithium peroxide (Li2O2) particles on the cathode surface area. SEM imaging of GDE cross-sections depicts that the (non-crystalline) product film formation at lower potentials during discharge with the TEGDME-based electrolyte results in a GDE pore clogging close to the O2 inlet, so that gas transport is hindered and the discharge ends at an earlier point. The higher cycling stability with LiTFSI/TEGDME, however, is attributed to (i) the apparently complete recovery of the GDE active surface by recharge and (ii) different parasitic reactions resulting in the formation of side product particles rather than films.

Journal of Power Sources, 2020

• Novel in-operando cell house for on-line electrochemical mass spectrometry. • Measure of gas release in cylindrical NMC/Graphite commercial cell. • Cycling at high Crates results in massive C 2 H 4 evolution and major capacity fade. • Main gas evolved at high cell voltages is CO 2 (onset >4.15 V). • Main gas evolved at low cell voltages is H 2 (onset <2.8 V).

Chemistry of Materials, 2012

The high capacity of the layered Li−excess oxide cathode is always accompanied by extraction of a significant amount of oxygen from the structure. The effects of oxygen on the electrochemical cycling are not well understood. Here, the detailed reaction scheme following oxygen evolution was established using real-time gas analysis and ex situ chemical analysis of the surface of the electrodes. A series of electrochemical/chemical reactions involving oxygen radicals constantly produced and decomposed lithium carbonate during cell operation. Moreover, byproducts, including water, affected the cycle life and rate capability: hydrolysis of the electrolyte salt formed hydrofluoric acid that attacked the surface of the electrode. This finding implies that protection of the electrode surface from damage, for example, by a coating or removal of oxygen radicals by scavengers, will be critical to widespread usage of Li−excess transition metal oxides in rechargeable lithium batteries.

Journal of the American Chemical Society, 2012

Transition-metal oxide and phosphate materials, commonly used for lithium battery devices, are active as oxygen evolution reaction (OER) catalysts under alkaline and neutral solution conditions. Electrodes composed of LiCoO 2 and LiCoPO 4 exhibit progressive deactivation and activation for OER catalysis, respectively, upon potential cycling at neutral pH. The deactivation of LiCoO 2 and activation of LiCoPO 4 are coincident with changes in surface morphology and composition giving rise to spinel-like and amorphous surface structures, respectively. The amorphous surface structure of the activated LiCoPO 4 is compositionally similar to that obtained from the electrodeposition of cobalt oxide materials from phosphate-buffered electrolyte solutions. These results highlight the importance of a combined structural and electrochemical analysis of the materials surface when assessing the true nature of the OER catalyst.

Turkish Journal of Materials, 2023

Lithium-ion batteries (LIBs) have significantly impacted our lives and are now found in various devices such as cell phones, laptops, and electric vehicles. An appropriate electrolyte was produced in LIBs via a twisting route, which relates to the progress of electrode chemistry. Based on recent research and discoveries, LIB has emerged as the technology of choice for storing electrical energy for use in mobile products and electric vehicles. This is due to LIBs' desirable qualities, such as their lightweight, high-energy density, small size, little memory effect, extended lifespan, and low pollution. In this method, a metal oxide is the cathode, and porous carbon is the anode. The electrochemical interaction of lithium with anode materials can generate intercalation products that are the basis for innovative battery systems. At room temperature, structural retention makes this reaction quick and reversible. This concise overview examines the progress of LIB technology and the impact of the materials used in different technologies on cell performance. The section summarizes the evolution of LIB cells and Li + ion storage into various materials and intercalation chemistry.

Journal of Power Sources, 2006

This study based on in situ differential electrochemical mass spectrometry (DEMS) in model cells with Li(Ni, Co, Al)O 2 and Li(Ni, Mn, Co)O 2 cathodes highlights various influence parameters on CO 2 evolution in lithium-ion batteries. The amount of CO 2 formation is increased by high temperatures and cell voltages, while the addition of vinylene carbonate (VC) decreases it. Lithium carbonate present in the cathode causes increased CO 2 formation in the initial cycles but has little influence during prolonged cycling. Two processes of CO 2 formation with different kinetics could be distinguished. The amount of CO 2 evolved depends strongly on the type of cathode active material.

Batteries, 2020

Temperature heavily affects the behavior of any energy storage chemistries. In particular, lithium-ion batteries (LIBs) play a significant role in almost all storage application fields, including Electric Vehicles (EVs). Therefore, a full comprehension of the influence of the temperature on the key cell components and their governing equations is mandatory for the effective integration of LIBs into the application. If the battery is exposed to extreme thermal environments or the desired temperature cannot be maintained, the rates of chemical reactions and/or the mobility of the active species may change drastically. The alteration of properties of LIBs with temperature may create at best a performance problem and at worst a safety problem. Despite the presence of many reports on LIBs in the literature, their industrial realization has still been difficult, as the technologies developed in different labs have not been standardized yet. Thus, the field requires a systematic analysis of the effect of temperature on the critical properties of LIBs. In this paper, we report a comprehensive review of the effect of temperature on the properties of LIBs such as performance, cycle life, and safety. In addition, we focus on the alterations in resistances, energy losses, physicochemical properties, and aging mechanism when the temperature of LIBs are not under control.

Journal of The Electrochemical Society, 1999

Among lithium transition metal oxides used as intercalation electrodes for rechargeable lithium batteries, LiCoO 2 is considered to be the most stable in the ␣-NaFeO 2 structure type. It has previously been believed that cation ordering is unaffected by repeated electrochemical removal and insertion. We have conducted direct observations, at the particle scale, of damage and cation disorder induced in LiCoO 2 cathodes by electrochemical cycling. Using transmission electron microscopy imaging and electron diffraction, it was found that (i) individual LiCoO 2 particles in a cathode cycled from 2.5 to 4.35 V against a Li anode are subject to widely varying degrees of damage; (ii) cycling induces severe strain, high defect densities, and occasional fracture of particles; and (iii) severely strained particles exhibit two types of cation disorder, defects on octahedral site layers (including cation substitutions and vacancies) as well as a partial transformation to spinel tetrahedral site ordering. The damage and cation disorder are localized and have not been detected by conventional bulk characterization techniques such as X-ray or neutron diffraction. Cumulative damage of this nature may be responsible for property degradation during overcharging or in long-term cycling of LiCoO 2 -based rechargeable lithium batteries.

Journal of the Electrochemical Society, 2015

Journal of Solid State Electrochemistry, 2001

Lithium nickelate (Li 0.88 Ni 1.12 O 2 ), lithium cobaltate (LiCoO 2 ) and lithium manganate (LiMn 2 O 4 ) were synthesized by fast self-propagating high-temperature combustion and their phase purity and composition were characterized by X-ray diraction and inductively coupled plasma spectroscopy. The electrochemical behaviour of these oxides was investigated with regard to potential use as cathode materials in lithiumion secondary batteries. The cyclic voltammograms of these cathode materials recorded in 1 M LiClO 4 in propylene carbonate at scan rates of 0.1 and 0.01 mV s ±1 showed a single set of redox peaks. Charge-discharge capacities of these materials were calculated from the cyclic voltammograms at dierent scan rates. The highest discharge capacity was observed in the case of Li 0.88 Ni 1.12 O 2 . In all the cases, at a very slow scan rate (0.01 mV s ±1 ) the capacity of the charging (oxidation) process was higher than the discharging (reduction) process. A strong in¯uence of current density on the charge-discharge capacity was observed during galvanostatic cycling of Li 0.88 Ni 1.12 O 2 and LiMn 2 O 4 cathode materials. LiMn 2 O 4 can be used as cathode material even at higher current densities (1.0 mA cm ±2 ), whereas in the case of Li 0.88 Ni 1.12 O 2 a useful capacity was found only at lower current density (0.2 mA cm ±2 ). For the fast estimation of the cycling behaviour of LiMn 2 O 4 , a screening method was used employing a simple technique for immobilizing microparticles on an electrode surface.

Energies

Lithium titanium oxide (Li4Ti5O12, LTO) is an attractive negative electrode for the development of safe—next-generation—lithium-ion batteries (LIBs). LTO can find specific applications complementary to existing alternatives for LIBs thanks to its good rate capability at high C-rates, fast lithium intercalation, and high cycling stability. Furthermore, LIBs featuring LTO electrodes are inherently safer owing to the LTO’s operating potential of 1.55 V vs. Li+/Li where the commonly used organic-based electrolytes are thermodynamically stable. Herein, we report the combined use of water-soluble sodium alginate (SA) binder and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-tetraglyme (1m-T) electrolyte and we demonstrate the improvement of the electrochemical performance of LTO-based electrodes with respect to those operating in conventional electrolyte 1M LiPF6-ethylene carbonate: dimethyl carbonate (LP30). We also tackle the analysis of the impact of combining the binder/electroly...