Li4Ti5O12 Anode Research Articles

Deep Eutectic Solvent (TOPO/D2EHPA/Menthol) for Extracting Metals from Synthetic Hydrochloric Acid Leachates of NMC-LTO Batteries

The recycling of lithium-ion batteries is increasingly important for both resource recovery and environmental protection. However, the complex composition of cathode and anode materials in these batteries makes the efficient separation of metal mixtures challenging. Hydrometallurgical methods, particularly liquid extraction, provide an effective means of separating metal ions, though they require periodic updates to their extraction systems. This study introduces a hydrophobic deep eutectic solvent composed of trioctylphosphine oxide, di(2-ethylhexyl)phosphoric acid, and menthol, which is effective for separating Ti(IV), Co(II), Mn(II), Ni(II), and Li+ ions from hydrochloric acid leachates of NMC (LiNixMnyCo1−x−yO2) batteries with LTO (Li4Ti5O12) anodes. By optimising the molar composition of the trioctylphosphine oxide/di(2-ethylhexyl)phosphoric acid/menthol mixture to a 4:1:5 ratio, high extraction efficiency was achieved. The solvent demonstrated stability over 10 cycles, and conditions for its regeneration were successfully established. At room temperature, the DES exhibited a density of 0.89 g/mL and a viscosity of 56 mPa·s, which are suitable for laboratory-scale extraction processes. Experimental results from a laboratory setup with mixer-settlers confirmed the efficiency of separating Ti(IV) and Co(II) ions in the context of their extraction kinetics.

Eliminating chemo-mechanical degradation of lithium solid-state battery cathodes during >4.5 V cycling using amorphous Nb2O5 coatings.

Lithium solid-state batteries offer improved safety and energy density. However, the limited stability of solid electrolytes (SEs), as well as irreversible structural and chemical changes in the cathode active material, can result in inferior electrochemical performance, particularly during high-voltage cycling (>4.3 V vs Li/Li+). Therefore, new materials and strategies are needed to stabilize the cathode/SE interface and preserve the cathode material structure during high-voltage cycling. Here, we introduce a thin (~5 nm) conformal coating of amorphous Nb2O5 on single-crystal LiNi0.5Mn0.3Co0.2O2 cathode particles using rotary-bed atomic layer deposition (ALD). Full cells with Li4Ti5O12 anodes and Nb2O5-coated cathodes demonstrate a higher initial Coulombic efficiency of 91.6% ± 0.5% compared to 82.2% ± 0.3% for the uncoated samples, along with improved rate capability (10x higher accessible capacity at 2C rate) and remarkable capacity retention during extended cycling (99.4% after 500 cycles at 4.7 V vs Li/Li+). These improvements are associated with reduced cell polarization and interfacial impedance for the coated samples. Post-cycling electron microscopy analysis reveals that the Nb2O5 coating remains intact and prevents the formation of spinel and rock-salt phases, which eliminates intra-particle cracking of the single-crystal cathode material. These findings demonstrate a potential pathway towards stable and high-performance solid-state batteries during high-voltage operation.

Fast-Charging Li4Ti5O12 Anode Driven By Light

The development of fast-charging lithium-ion batteries (LIBs) is crucial for achieving significant market adoption of electric vehicles (EVs). The successful achievement of fast-charging LIBs depends on efficient charge transfer and the diffusivity of lithium ions. The photo-assisted battery system exhibits promising fast-charging properties. Previous research has shown that direct exposure to white light can induce a more oxidized center in a spinel LiMn2O4 (LMO) cathode, accelerating its charging rate.[ 1] Recently, our group found that illumination with red light on an operating LMO cathode induces an Mn d-d electron excitation, simultaneously shrinks the Mn-Mn lattice, and facilitates faster delithiation of the LMO cathode.[ 2] Consequently, the charging time of the battery decreases. This encourages us to consider whether the photon energy from a specific wavelength of light can also enhance the lithiation process on the anode side. Spinel Li4Ti5O12 (LTO) is a promising material for faster-charging anodes due to its small volume charge and high-rate capability in lithium intercalation. However, the system displays slow lithium diffusivity due to poor bulk ionic conductivity. To examine the photon effect of light on these anodes, we demonstrate the photo-accelerated fast-charging (lithiation process) mechanism with an LTO spinel anode.The thin film LTO's energy band gap (Eg), approximately 3.4 eV, was determined through intense UV-visible (UV-Vis) absorption spectrum analysis, assessed in a transmission mode employing Tauc’s Law. This indicates that an LED light with photon energy around 3.4 eV might trigger rapid charging by exciting electron transfer to the T-t2g band. To explore the impact of light on the fast-charging behavior of the LTO electrode, current was measured while applying a constant voltage of 1.2 V. During the 20-minute chronoamperometry experiment, utilizing the 3.4 eV UV LED to illuminate the cell resulted in a progressive increase in current. This current increase peaked at approximately 200s, leading to a maximum average capacity increase of 13 mA h g-1. This suggests that UV illumination accelerates the lithiation process compared to the dark state, particularly favoring the early lithiation stage. Subsequently, a red LED emitting 2 eV photon energy was used to illuminate the same cell, resulting in no discernible change in current levels compared to the dark state. Electrochemical impedance spectroscopy (EIS) further revealed a significant reduction in charge transfer resistance of the window cell when illuminated with UV light compared to both the dark state and red illumination. This alteration in electrode reaction kinetics at the interface suggests a distinct influence of different light wavelengths on the charging process.In addition to assessing charge transfer at the electrode interface, galvanostatic intermittent titration technique (GITT) analysis was conducted at a 2 C rate to further elucidate diffusion within the LTO electrode. The GITT curves reveal that the diffusion of Li+ ions was approximately 1.3 times faster when the cell was illuminated by UV light compared to dark conditions. Consequently, we deduce that photo-accelerated fast charging can also occur during the lithiation process (reduction reaction) of anode materials, driven by optical forces.To delve into the underlying mechanisms, we conducted first-principles density functional theory (DFT) calculations. The outcomes revealed that the generation of additional electrons in LTO results in a reduction in the bandgap and shifts the Fermi level above the conduction band minimum, effectively transforming LTO into an active conductor of electricity. These calculations indicate that UV light illumination has the capability to surmount the bandgap of LTO, generating electron-hole pairs and thereby facilitating charge transfer and lithium-ion diffusion.In conclusion, our study showcased that UV light illumination on the LTO anode can lead to a faster charging speed of approximately 17% compared to dark conditions. We posit that the observed phenomenon of photo-accelerated fast charging in LTO is linked to the formation of electron-hole pairs in intrinsically wide-bandgap insulators or semiconducting materials. This discovery holds considerable implications for the advancement of fast charging technologies for lithium-ion batteries, potentially mitigating range anxiety concerns and facilitating the widespread adoption of electric vehicles.Acknowledgments: This work was supported by funding from Royal Dutch Shell plc. Argonne National Laboratory operates under contract no. DE-AC02-06CH11357 with the U.S. Department of Energy Office of Science. We gratefully acknowledge use of the Bebop or Swing or Blues cluster in the Laboratory Computing Resource Center at Argonne National Laboratory and supported by the U.S. Department of Energy Office of Science.Reference[1] A. Lee et al., Nat. Commun., 10, 4946 (2019).[2] J. Lipton et al., Cell Reports Physical Science, 3, 101051 (2022).

High-Entropy Spinel Oxide as Conversion Anodes for Li-Ion Batteries

The burgeoning sector of electric vehicles has significantly spurred the exploration of high-energy density and long-term cycling life electrode materials for advanced lithium-ion batteries (LIBs). Presently, the constrained capacity of commercialized graphite (LiC6: 372 mAh g–1) and Li4Ti5O12 (Li7Ti5O12: 175 mAh g–1) anodes falls short of meeting the heightened requirements for energy density in such applications. Transition metal oxides (TMOs, MxOy) with conversion reaction have been widely scrutinized as next-generation LIB anode materials owing to their resonable reversible capacity in comparison to conventional graphite anode. Unfortunately, the crystal structures of TMOs typically undergo severe degradation during rapid conversion/alloying reactions over continuous lithiation/delithiation process. This phenomenon leads to rapid capacity decay, poor reversibility, and consequently, a significant hindrance to their applicability as LIB anodes. In recent developments, high-entropy oxides (HEOs), analogous to high-entropy metallic alloys (HEMAs), have garnered considerable interest as an emerging class of solid solutions, involving a multitude of metalic cations in an equimolar ratio. Intriguingly, the high configurational entropy (Sconfig) present plays a crucial role in stabilizing their single-phase crystal structures. Pioneering this concept, Rost et al. introduced entropy-stabilization into TMOs, successfully creating the rocksalt HEO, (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)O with the value of Sconfig ≥ 1.6R. Leveraging substantial compositional flexibility by modifying the stoichiometry and incorporating diverse cationic species, HEOs possess unforeseen and distinctive physicochemical properties. Consequently, they have been applied across diverse domains, encompassing catalysts, thermoelectrics, superionic conductors, and battery electrodes.The initial investigation into HEOs as LIB anode materials featured the rocksalt-type composition (Co0.2Cu0.2Mg0.2Ni0.2Zn0.2)O. Sarkar et al. demonstrated its remarkably reversible Li-storage properties, showcasing stable cycling performance with reversible capacities ranging from 500 to 700 mAh g−1 at current density of 200 mA g−1 even after 300 cycles. Subsequently, Patra et al. introduced the single-phase spinel HEO (Fe0.2Cu0.2Ni0.2Cr0.2Mn0.2)3O4 as a LIB anode, achieving a specific capacity of 640 mAh g−1 at current density of 500 mA g−1 over 400 cycles. Impressively, the specific capacity remained at 596 mAh g−1 at a high current density of 2.0 A g−1 after 1200 cycles, retaining 86.2%. In contrast to conventional TMOs, entropy-stabilized HEOs possess the ability to maintain partial stability even in a fully lithiated state, acting as a matrix to accommodate conversion reactions and greatly improve reversible cycling stability. Nevertheless, rocksalt HEOs encounter challenges stemming from inadequate active components, thereby affecting the reversible capacity during cycling. In contrast, the spinel structure of HEOs facilitates ionic diffusion through three-dimensional pathways. Furthermore, the induction of oxygen vacancies by multivalent metallic cations at Wyckoff positions (tetrahedral and octahedral) in the spinel serves to augment ionic conduction. Therefore, the imperative further development of new spinel HEO anodes necessitates the rational design of active metallic cation components within HEOs. Concerning the enhancement of Li-storage properties in HEO anodes for LIBs, a comprehensive understanding of their Li storage mechanisms during Li-insertion/extraction is critically important.Herein, we present the development of a high-performance conversion-type anode comprising new multi-component HEOs with 5, 6, 7, and 8 cations for LIBs, synthesized through rapid techniques, specifically solution combustion synthesis (SCS). Additionally, we characterize their in-depth structural information using synchrotron X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). With an increase in the number of cations, the HEO anodes exhibit improved Li-storage properties, including enhanced cycling performance and rate capability. To further evaluate the electrochemical performance of HEOs synthesized by different methods, we selected a specific composition based on its electrochemical performance and synthesized it using solvothermal synthesis. Subsequently, we assessed the electrochemical performance of these samples. Furthermore, we investigated the Li-storage mechanism of HEOs during lithiation/delithiation through ex-situ analytical techniques, encompassing XRD and XAS. The results collectively indicate that the highly reversible conversion reaction in cycled HEO anodes contributes to their outstanding Li-storage characteristics, facilitating stable cycling retention and fast rate capability. The findings of this study delve deeply into the highly reversible Li-storage in HEOs through conversion reactions, with potential implications extending to a broader class of HEO anodes, suggesting the promise of advanced LIBs exhibiting exceptional electrochemical performance.

Preparation of Amorphous SiO2 Coated Li4Ti5O12 Anode and Their High Cycleability

In recent years, lithium-ion batteries (LIBs) have been commonly used in batteries for electric vehicles and smartphones because of their higher capacity, higher energy density, and longer life than other rechargeable batteries. The viewpoint of longer life in LIBs, Li4Ti5O12 (LTO) oxide anode is one of the possible alternative materials. LTO possesses less than 1% volume change property during charging and discharging, which prevents poor contact with active materials due to less cracking. Furthermore, LTO is operated at a high voltage of 1.55 V vs Li/Li+, so metallic Li dendrites do not grow. However, it is well known that side reactions such as SEI formation and gas generation are caused at the interface between the electrolyte and LTO. Therefore, in this study, in order to reduce side reactions at the interface, the LTO surface was coated with amorphous SiO2, which is electrochemically stable and inexpensive, to improve the rate and cycle characteristics. An amorphous SiO2-coated LTO (coated-LTO) was prepared by a sol-gel method using TEOS as the starting material. 5wt% and 10wt% of TEOS vs LTO were used to prepare coated LTO with different coating thicknesses. The obtained powders were analyzed by XRD, SEM/EDS, XPS, and AES for crystal structure and surface conditions. A 2032-type coin cell was fabricated for battery characterization. Li foil was used as the counter electrode and LiPF6 EC:DEC (3:7 vol%) as the liquid electrolyte. Charge-discharge measurements were carried out using CC-mode under a measured voltage range of 1.0 V to 3.0 V and a theoretical capacity of 175 mAh/g. To evaluate the C-rate performance of LIBs using coated-LTO, the C-rate was varied from 0.1C to 40C. In the cycle test, 1000 charge-discharge cycles were conducted at 3C, with 1 hour of OCV after charge and discharge in all cycles. EIS measurements were taken before and after charging and discharging to evaluate interfaces caused by side reactions. The results of the XRD analysis showed that the crystal structure was not disturbed by the coating, meaning that the coating did not destroy the LTO through the coating process. The average thickness of the SiO2 layer was 1-3 nm and 2-4 nm for the sample coated with TEOS at a concentration of 5wt% and 10wt% vs LTO, respectively. The C-rate performance of the charge-discharge test shows that the discharge capacity slightly decreased at low C-rate operation due to the coating, meaning that SiO2 should be a resistance of Li-ion migration at the interface. On the other hand, at high rates exceeding 2.0C, the discharge capacity of coated-LTO was higher than that of pure LTO. At 40C, the discharge capacity was approximately 80 mAh/g, suppressing energy loss at high C-rate operation. In the cycling test at 3C, only the sample coated with 10wt% coated-LTO achieved 1000 reversible cycles, and the capacity retention after 1000 cycles was 93.3%.(show in figure) The electrochemical impedance spectroscopy results should suggest that part of the improvement in battery properties was due to the prevention of SEI formation.

Ti Doping Decreases Mn and Ni Dissolution from High-Voltage LiNi0.5Mn1.5O4 Cathodes.

LiNi0.5Mn1.5O4 (LNMO), with its high operating voltage, is a favorable cathode material for lithium-ion batteries. However, Ni and Mn dissolution and the associated low cycle life limit their widespread adoption. In this work, we investigate titanium doping as a strategy to mitigate Mn and Ni dissolution from LNMO electrodes. We demonstrate bulk doping of Ti in LNMO up to nominal compositions of x = 0.15 in LiNi0.5Mn1.5-x Ti x O4. Electrochemical characterization shows that titanium doping enhances the cycle life in LNMO-based half- and full cells with a negligible decrease in capacity or rate capability. Half-cells with LiNi0.5Mn1.35Ti0.15O4 cathodes and lithium anodes exhibited a capacity retention of 90% after 300 cycles at 1C. Li4Ti5O12/LiNi0.5Mn1.35Ti0.15O4 full cells with Li4Ti5O12 anodes cycled at 1C rate to 100% depth of discharge retained ∼73% of the original capacity at the end of 1000 cycles. Our work shows that cathode modification strategies could still be used for enhancing the electrochemical performance of high-voltage cathodes, while using conventional Li-ion battery electrolytes. Improving the cathode stability in conjunction with electrolyte modification could enable the development of practical high-voltage Li-ion batteries.

Facile one-step fabrication of Li4Ti5O12 coatings by suspension plasma spraying

Spinel Li4Ti5O12 (LTO) is a promising anode material for solid state thin film batteries (SSTB) due to its almost-zero volume change and promising Li-ion mobility. However, preparing LTO anodes for SSTB demands tedious vacuum-based processing steps that are not cost effective. In this context, the present study embarks on evaluating the versatile suspension plasma spraying (SPS) approach to fabricate LTO coatings without using any binder. The microstructure and stoichiometry of the fabricated LTO coatings developed through the SPS route reveals retention of ∼76 wt.% of the spinel LTO from the starting feedstock, with minor amounts of rutile and anatase TiO2. The SPS experiments yielded varying thickness build up rates of the LTO coatings depending on the processing parameters adopted. The electrochemical data of the produced LTO based electrode tested in a half-cell through galvanostatic cycling show reversible lithiation and delithiation at expected potential, thereby validating the promise of the SPS technique for potential fabrication of SSTB components once fully optimized.

Deciphering the structural and kinetic factors in lithium titanate for enhanced performance in Li+/Na+ dual-cation electrolyte

The widespread application of Li4Ti5O12 (LTO) anode in lithium-ion batteries has been hindered by its relatively low energy density. In this study, we investigated the capacity enhancement mechanism of LTO anode through the incorporation of Na+ cations in an Li+-based electrolyte (dual-cation electrolyte). LTO thin film electrodes were prepared as conductive additive-free and binder-free model electrodes. Electrochemical performance assessments revealed that the dual-cation electrolyte boosts the reversible capacity of the LTO thin film electrode, attributable to the additional pseudocapacitance and intercalation of Na+ into the LTO lattice. Operando Raman spectroscopy validated the insertion of Li+/Na+ cations into the LTO thin film electrode, and the cation migration kinetics were confirmed by ab initio molecular dynamic (AIMD) simulation and electrochemical impedance spectroscopy, which revealed that the incorporation of Na+ reduces the activation energy of cation diffusion within the LTO lattice and improves the rate performance of LTO thin film electrodes in the dual-cation electrolyte. Furthermore, the interfacial charge transfer resistance in the dual-cation electrolyte, associated with ion de-solvation processes and traversal of the cations in the solid-electrolyte interphase (SEI) layer, are evaluated using the distribution of relaxation time, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Our approach of performance enhancement using dual-cation electrolytes can be extrapolated to other battery electrodes with sodium/lithium storage capabilities, presenting a novel avenue for the performance enhancement of lithium/sodium-ion batteries.

High Performance Ti3+ Self-Doped Li4Ti5O12 Anode Materials Synthesized by an Electrochemical Method in Molten Salt

A simple synthesis for the Ti3+-doped, small Li4Ti5O12 is favorable for its application as an anode material of lithium-ion batteries. This study presents a direct synthesis method of high-performance Li4Ti5O12 (LTO-Ti) with the Ti3+ self-doped and uniformly small in size. It is carried out by the redox of an electrochemical electrode pair of Ti and Fe2O3 at a constant potential in molten KCl-LiCl salt with Li2CO3. The synthesis mechanism and the effect of synthesis conditions on the formation and properties of LTO-Ti were investigated in detail. The LTO-Ti with an average size of approximately 400 nm is prepared by the ionic level synthesis method, and exhibits a superior specific capacity of 130.5 mAh·g−1 at 10 C current density, which is 73.6% of its average specific capacity at 1 C. Moreover, it also shows good cycling stability with a specific capacity of 127.2 mAh·g−1 after 1000 cycles at 5 C (capacity retention of 96.9%). This synthesis is secure and prospective.

Continuum insight into the effects of electrode design parameters on the electrochemical performance of lithium-ion batteries

Lithium-ion batteries energy and power density strongly depend on the type of active material and the electrode design parameters. An in-depth understanding of the effect of battery design parameters on their electrochemical performance is experimentally expensive and hence requires the utilization of cheaper continuum scale models. Here, using a lithium-ion cell composed of LiFePO4 cathode, Li4Ti5O12 anode and a porous separator filled with a liquid electrolyte as an example, we demonstrate the use of an experimentally validated pseudo-two-dimensional (P2D) model in one-dimension to explore the effects of different cell design parameters on the discharge capacity at different current rates. The model is simulated in two-dimensional to instantly visualize the concentration distribution of Li ions in the electrode at high discharge current rates. The continuum model unravels that the solution phase diffusion limitation is the main factor inhibiting the performance of thick electrodes at high current rates and the Li4Ti5O12 anode is the limiting electrode. These findings using continuum models provide guidance for and accelerate the optimization of electrode architecture for enhancing the performance of lithium-ion batteries.

Freeze-drying synthesis of metal element (Zr, Cr, Co)–doped Li4Ti5O12 anode material for enhanced electrochemical energy storage in lithium-ion batteries

Freeze-drying synthesis of metal element (Zr, Cr, Co)–doped Li4Ti5O12 anode material for enhanced electrochemical energy storage in lithium-ion batteries

Metal-Doped NASICON/Polymer Composite Solid Electrolyte for Lithium Titania Anode in Lithium-Ion Batteries.

This study reports five types of metal-doped (Co, Cu, Sn, V, and Zr) NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP)/polymer composite solid electrolytes (CSEs) enabling Li4Ti5O12 (LTO) anodes to have high rate capability and excellent cycling performance. The high Li+-conductivity LATP samples are successfully synthesized through a modified sol-gel method followed by thermal calcination. We find that the cation dopants clearly influence the substitution of Al for Ti, with the type of dopant serving as a crucial factor in determining the ionic conductivity and interfacial resistance of the solid electrolyte. The CSE containing poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and Sn-LATP shows an ionic conductivity of 1.88 × 10-4 S cm-1 at ambient temperature. The optimum conductivity can be attributed to alterations in the lattice parameters and Li+ transport pathways owing to Sn doping. The solid-state cell equipped with the LTO-supported CSE containing Sn-LATP fillers demonstrates both excellent high rate capability at 5 C (with a capacity retention of 86% compared to the value measured at 0.2 C) and superior cycling stability, maintaining high Coulombic efficiency (>99.0%) over 510 cycles. These findings indicate that the proposed CSE is highly promising for use in solid-state lithium batteries with desirable charge-discharge properties and high durability.

Functional AlF3 modification over 5 V spinel LiCoMnO4 cathode for Li-ion batteries

We report the improved electrochemical activity of the 5 V LiCoMnO4 (LCMO) cathode with the functionalization of AlF3 coating. LCMO@AlF3 is prepared by adopting the co-precipitation technique followed by a wet coating by altering the concentration of AlF3 by 1–3 wt.%. LCMO@AlF3 exhibits improvement in the electrochemical performance compared to pristine LCMO. In addition, LCMO@AlF3 exhibits superior electrochemical performance with specific capacities of 107, 102, and 95 mAh g−1 and retentions of 68, 77, and 74% after 100 cycles for 1, 2, and 3 wt.% AlF3 coating. However, pristine LCMO shows a specific capacity of 105 mAh g−1 with a retention of 48% after 100 cycles. Also, LCMO@AlF3 exhibits a decrement in the irreversible capacity loss (ICL) compared to pristine LCMO, which enhances the coulombic efficiency of the former compared to the latter. Further, the AlF3 coating of 2 and 3 wt.% has been optimized to exhibit excellent electrochemical performance. The diffusion coefficients are calculated from cyclic voltammetric and electrochemical impedance spectroscopic techniques and are in the order of ∼10−12 cm2 s−1. Further, in-operando and in-situ impedance studies are conducted to authenticate the electrochemical activity observed in half-cell studies. In full-cell assembly with Li4Ti5O12 (LTO) anode, the LCMO@AlF3: 2–3 wt.% exhibits better electrochemical performance compared to its bare configuration. In addition, the electrochemical activity at various temperature (−10 to 25 °C) conditions is performed and reported.

Fabrication of Li4Ti5O12 (LTO) as Anode Material for Li-Ion Batteries.

The most popular anode material in commercial Li-ion batteries is still graphite. However, its low intercalation potential is close to that of lithium, which results in the dendritic growth of lithium at its surface, and the formation of a passivation film that limits the rate capability and may result in safety hazards. High-performance anodes are thus needed. In this context, lithium titanite oxide (LTO) has attracted attention as this anode material has important advantages. Due to its higher lithium intercalation potential (1.55 V vs. Li+/Li), the dendritic deposition of lithium is avoided, and the safety is increased. In addition, LTO is a zero-strain material, as the volume change upon lithiation-delithiation is negligible, which increases the cycle life of the battery. Finally, the diffusion coefficient of Li+ in LTO (2 × 10-8 cm2 s-1) is larger than in graphite, which, added to the fact that the dendritic effect is avoided, increases importantly the rate capability. The LTO anode has two drawbacks. The energy density of the cells equipped with LTO anode is lower compared with the same cells with graphite anode, because the capacity of LTO is limited to 175 mAh g-1, and because of the higher redox potential. The main drawback, however, is the low electrical conductivity (10-13 S cm-1) and ionic conductivity (10-13-10-9 cm2 s-1). Different strategies have been used to address this drawback: nano-structuration of LTO to reduce the path of Li+ ions and electrons inside LTO, ion doping, and incorporation of conductive nanomaterials. The synthesis of LTO with the appropriate structure and the optimized doping and the synthesis of composites incorporating conductive materials is thus the key to achieving high-rate capability. That is why a variety of synthesis recipes have been published on the LTO-based anodes. The progress in the synthesis of LTO-based anodes in recent years is such that LTO is now considered a substitute for graphite in lithium-ion batteries for many applications, including electric cars and energy storage to solve intermittence problems of wind mills and photovoltaic plants. In this review, we examine the different techniques performed to fabricate LTO nanostructures. Details of the synthesis recipes and their relation to electrochemical performance are reported, allowing the extraction of the most powerful synthesis processes in relation to the recent experimental results.

Metal sulfides encapsulated in doped carbon aerogel towards superior and safe energy storage: Two birds with one stone

Up to now, lithium/sodium ion batteries (LIBs/SIBs) are deemed as the ideal candidates for traditional fossil energy. However, the absence of suitable Li+/Na+ reservoirs and the hazard of thermal runway have plagued their usages. Using Li4Ti5O12 or TiO2 anode promotes the thermal safety of LIBs/SIBs but reduce their electrochemical property. How to achieve the balanced performances has been an urgency. Here, we have delicately designed a 3D micro-nanostructure of CoS2/doped carbon aerogel (CoS2@NCA), via “killing two birds with one stone” strategy. When used as LIBs anode, CoS2@NCA delivers a high capacity of 639.5 mAh g−1 after operating at 1 A g−1 for 250 cycles, giving a low-capacity attenuation rate of 0.048 % per cycle. Meanwhile, the reduced maximum temperature and maximum heating rate of thermal runaway (TR) are observed for cell. When used as SIBs anode, CoS2@NCA delivers a high capacity of 620.9 mAh g−1 at 100th cycle as working at 1 A g−1. Likewise, the activation energy for TR is promoted. Overall, the utilization of CoS2@NCA enables the superior and safe energy storage.

Effect of Si Doping and Active Carbon Surface Modifications on the Structure and Electrical Performance of Li4Ti5O12 Anode Material for Lithium-Ion Batteries

Effect of Si Doping and Active Carbon Surface Modifications on the Structure and Electrical Performance of Li4Ti5O12 Anode Material for Lithium-Ion Batteries

High-power recycling: upcycling to the next generation of high-power anodes for Li-ion battery applications

Upcycling current high power electrodes (Li4Ti5O12) towards the next generation of titanium niobium oxide materials, while reclaiming a critical element: lithium.

Failure mechanisms of the Li(Ni0.6Co0.2Mn0.2)O2-Li4Ti5O12 lithium-ion batteries in long-time high-rate cycle.

With the ever-growing widespread use of lithium-ion batteries in heavy machinery and daily life, the demand for improved longevity and high-rate performance is escalating. While Li4Ti5O12 (LTO) batteries excel in safety and cycling performance, their full potential for long-term, high-rate cycling still yet remains unrealized. In this paper, we present an analysis of a pouch battery with an LTO anode system that was cycled for an extended period at high rates. We compared the performance changes and internal component properties between fresh and cycled batteries. Our results reveal that, after tens of thousands of high-rate cycles, microcracks emerged on the cathode electrode material (NCM622) particles of the battery, whereas the LTO remained largely unchanged. Additionally, we observed significant electrolyte reduction, characterized the separator surface, and measured its properties. Our findings indicate that the electrolyte reactions are the primary cause of battery failure, leading to capacity fading and impedance increase. This research provides valuable insights into the failure mechanisms of lithium-ion batteries at high rates, thus contributing to the improvement of high-rate lithium-ion batteries.

Chemomechanical Failure of Solid Composite Cathodes Accelerated by High-Strain Anodes in All-Solid-State Batteries

Lithium-ion batteries (LIBs) have played a major role in energy storage, particularly, for portable electronic devices. However, the energy density of the LIB has reached its limit, which is not high enough to fulfill an ever-growing demand for long-lasting batteries. More importantly, safety issues arising from flammable liquid electrolytes are considered critical problems to be addressed for large-scale batteries. All-solid-state batteries (ASSBs) with non-flammable solid electrolytes (SEs) have been emerging as a promising alternative to liquid-electrolyte-based LIBs. Among various types of SEs, sulfide-based materials, e.g., Li6PS5Cl (LPSCl), have gained much attention, owing to their high ionic conductivity at room temperature.To develop ASSBs with high energy density, Li metal/alloys or Li-free Ag-C composites have been widely studied as anode materials; however, they undergo large volume changes during repeated charge-discharge cycling. In addition to the morphological and mechanical degradation of the anode itself, massive volume changes exert additional mechanical stresses on the cell components and interfaces between them, which can cause accelerated performance decay. While a few studies have been reported on the mechanical deformation of the SE layers induced by the volume changes of anodes, possible degradation of the composite cathodes has been largely overlooked.Herein, we present a comparative study of ASSBs assembled with high-strain (Li-In) and zero-strain (Li4Ti5O12 (LTO)) anodes to understand the impact of anode volume changes on chemomechanical degradation behaviors of solid composite cathodes. An ASSB cell was composed of polycrystalline NCA-LPSCl composite cathode, LPSCl separator layer, and either Li-In or LTO anode. The Li-In-based cell suffered from severe capacity loss after 120 cycles, whereas the LTO-based cell showed a stable capacity retention over 200 cycles. Impedance decoupling via three-electrode set-up indicated rapid increases in interfacial and diffusion (Warburg) impedances of the composite cathode in the Li-In-based cell during cycling, as compared with those in the LTO-based cell.In-depth chemical, electrochemical, and microstructural analyses revealed that the high-strain Li-In anode perturbs the structural integrity of the composite cathode and facilitates “dynamic” contacts between the cathode constituents upon repeated cycling. This leads to the enhanced parasitic interfacial reactions, as evidenced by the increased amount of resistive phases (e.g., P2S x , Li2S, and PO4 3-) in the cathode of the Li-In-based cell. The resulting chemically/electrochemically inhomogeneous interfaces between NCA and LPSCl cause localized concentrations of diffusion-induced stress within NCA, leading to the accelerated cracking of NCA aggregates. This study highlights the accelerated degradation phenomena of composite cathodes driven by high-strain anodes and provides insights into the design of ASSBs with long cycle lifetimes.

Fabrication and Characterization of LiNi1/3Mn1/3Co1/3O2/Li0.6La0.4TiO3/Li4Ti5O12 Full Cell All-Solid-State Thin Film Li-Ion Batteries for Energy Applications

Recent days, natural calamities caused by the global warming and climate changes are major concern for the entire globe and there is a pressing need to address such issues to save the mankind from further havoc and devastation. To reduce the carbon emission, countries are shifting dramatically towards renewable sources for their energy needs for their day-to-day life. Li ion batteries are in the forefront of the battle towards the sustainable growth and development due to their high energy density and renewable in nature. In the present case, we report on development of thin film based all-solid-state batteries (ASSB) for energy applications. LiNi1/3Mn1/3Co1/3O2 (NMC), Li0.6La0.4TiO3 (LLTO) and Li4Ti5O12 (LTO) materials are employed as a cathode, solid electrolyte and anode layers for fabricating a full cell all-solid-state thin film batteries. All the layers are fabricated employing RF sputtering technique. Before fabricating the full cell, individual layers are fabricated and their electrochemical and/or ionic conductivity properties are explored. Li0.6La0.4TiO3 solid electrolyte thin films are seen to exhibit room temperature in-plane ionic conductivity in the order of 10-3 S/cm. NMC thin film with the thickness of 100 nm exhibits specific capacity of 91 µAh/cm2 and the redox peaks at 3.8 V and 3.5 V. LTO anode thin films shows the specific capacity close to 100 mAh/cm2and the redox peaks around 1.5 V. XRD pattern of NMC/LLTO/LTO full cell shows the diffraction peaks corresponding to all the three layers. Cross-sectional scanning electron microscope (SEM) image indicates the uniform coating and presence of all the layers. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) along with the energy dispersive X-ray is employed to image the cross-sectional details and the elements present in each layer of the full cell all-solid-state thin film battery. Impedance spectroscopy was employed to calculate the total conductivity of the fabricated full cell. Obtained results indicates that the full cell NMC/LLTO/LTO thin film batteries can be fabricated employing a sputtering technique for the energy applications. Figure 1