Lithium lanthanum titanate perovskite as an anode for lithium ion batteries

Crystal structure regulation of trititanium pentoxide for advanced zero-strain lithium storage anode

Significant advancements have been made in electric vehicles and consumer devices. However, lithium-ion batteries with commercial graphite anodes still face challenges owing to their sluggish lithium-ion kinetics, low lithiation potential, and limited cycle stability. Consequently, there is a considerable research interest in developing new anode materials with rich resources, "zero-strain" characteristics for long-term cycling, and outstanding electrochemical properties. In this study, we thoroughly examine the relationship between the structure and electrochemical characteristics of λ and β phases of titanium pentoxides (Ti3O5). The findings indicate that the β phase of Ti3O5 exhibits a overall electrochemical performance compared to the λ phase. Moreover, β-Ti3O5 electrodes deliver a low, yet safe average operating potential of 0.82 V versus Li/Li+ and a reversible specific capacity of 181.9 mA h/g at 0.1 A/g, thereby significantly outperforming λ-Ti3O5 electrodes, with a value of only 55.7 mA h/g. The performance difference can be primarily attributed to the changes in the crystal structure, with the β phase exhibiting a lower energy barrier for lithium-ion diffusion than the λ-phase. Moreover, the β-Ti3O5 electrodes exhibit an good rate performance (capacity retention of 49.5 % at 10 A/g) and good cycling stability (absence of capacity degradation after 2000 cycles at 1.0 A g-1). These advantages suggest that β-Ti3O5 is a promising anode material for reliable, rapid-charging, and secure lithium-ion storage.

Revealing the Interplay of Local Environments and Ionic Transport in Perovskite Solid Electrolytes

Solid-state ionic conduction is significantly influenced by bottleneck sizes, which impede ion diffusion within solid lattices. Using aberration-corrected scanning transmission electron microscopy and multislice electron ptychography, we directly observed that increased La occupancy in the perovskite solid electrolyte Li0.5La0.5TiO3 correlates with reduced bottleneck sizes formed by four oxygen atoms connecting neighboring A-site cages. This correlation was also confirmed in local aperiodic regions, where smaller bottleneck sizes due to increased La occupancies affect the directionality and dimensionality of the Li+ ion conductivity. Furthermore, while prior studies have focused on averaged Li+ ion diffusion across different bottleneck areas or chemical environments, by devising a molecular dynamics (MD)-based methodology, we quantify the diffusivity of Li+ ions through specific bottleneck regions. Atomistic simulations, including nudged elastic band calculations and this MD-based methodology, revealed that larger bottleneck sizes correlate with smaller local migration barriers and higher local diffusivity. This study elucidates the relationship among local chemistry, lattice structure, and Li+ ion transport, providing insights for the design of advanced oxide solid electrolytes.

Transient Phase-Mediated Li+ Transportation in the Lithium Lanthanum Titanate Solid-State Electrolyte

The lithium lanthanum titanium oxide (LLTO) perovskite is one type of superior lithium (Li)-ion conductor that is of great interest as a solid-state electrolyte for all-solid-state lithium batteries. Structural defects and impurity phases formed during the synthesis of LLTO largely affect its Li-ion conductivity, yet the underlying Li+ diffusion mechanism at the atomic scale is still under scrutiny. Herein, we use aberration-corrected transmission electron microscopy to perform a thorough structural characterization of the LLTO ceramic pellet. We reveal a prevalent transient phase transition of (La, Ti)2O3 existing at the antiphase boundaries between single-crystalline LLTO domains. This transient phase exhibits a specific crystal orientation with the LLTO phase and shows a gradual structural transition to a tetragonal LLTO structure, which enables detailed crystallographic analysis to correlate their formation to the sintering process of LLTO powders into ceramic pellets. We also find that Li diffusion is retarded by this phase and correlated with the excess amount of La, which is corroborated by the theoretical evaluation of the atomistic mechanisms of Li diffusion across this phase.

Oriented Crystal Growth of Li0.33La0.557TiO3 Nanowire Induced by One-Dimensional Polymer Sheath toward Rapid Lithium-Ion Transfer

Superionic conductor-based solid-state electrolytes with preferred crystal structures hold great promise for realizing ultrafast lithium-ion (Li+) transfer, which is urgently desired for all-solid-state lithium batteries. However, the precise control of crystal growth of superionic conductors is still challenging since the crystals always spontaneously grow to disordered structures with the lowest internal energy to ensure thermodynamic stability. Herein, a coaxial nanowire with a polyvinylpyrrolidone (PVP) sheath and a Li0.33La0.557TiO3 (LLTO) precursor core (PVP/LLTO-caNW) is prepared through coaxial electrospinning, followed by sintering into LLTO nanowire with an oriented crystal structure (LLTO-caNW). We demonstrate that the one-dimensional PVP sheath as a sacrificial layer generates uniform and the strongest adsorption ability on the (110) phase among different LLTO crystal planes, which induces the crystal to preferentially grow along the c-axis (the fastest Li+ transfer direction) during the nucleation and growth processes. As a result, the prepared LLTO-caNW displays an ultrahigh bulk ionic conductivity of 3.13 × 10-3 S cm-1, exceeding most LLTO crystals and approaching the theoretical conductivity. Meanwhile, the oriented crystal growth imparts to LLTO-caNW significantly reduced grain boundary resistance, and the grain-boundary conductivity reaches up to 1.09 × 10-3 S cm-1. This endows the composite solid electrolyte with high ionic conduction performance and superior cycle stability in the assembled all-solid-state lithium battery.

Unveiling crystal orientation-dependent interface property in composite cathodes for solid-state batteries by in situ microscopic probe

A critical bottleneck toward all-solid-state batteries lies in how the solid(electrode)-solid(electrolyte) interface is fabricated and maintained over repeated cycles. Conventional composite cathodes, with crystallographically distinct electrode/electrolyte interfaces of random particles, create complexities with varying (electro)chemical compatibilities. To address this, we employ an epitaxial model system where the crystal orientations of cathode and solid electrolyte are precisely controlled, and probe the interfaces in real-time during co-sintering by in situ electron microscopy. The interfacial reaction is highly dependent on crystal orientation/alignment, especially the availability of open ion channels. Interfaces bearing open ion paths of NCM are more susceptible to interdiffusion, but stabilize with the early formed passivation layer. Conversely, interfaces with closed ion pathway exhibit stability at intermediate temperatures, but deteriorate rapidly at high temperature due to oxygen evolution, increasing interfacial resistance. The elucidation of these distinct interfacial behaviors emphasizes the need for decoupling collective interfacial properties to enable rational design in solid-state batteries.

Heterogeneous-Structured Molybdenum Diboride as a Novel and Promising Anode for Lithium-Ion Batteries

With the development of electric vehicles, exploiting anode materials with high capacity and fast charging capability is an urgent requirement for lithium-ion batteries (LIBs). Borophene, with the merits of high capacity, high electronic conductivity and fast diffusion kinetics, holds great potential as anode for LIBs. However, it is difficult to fabricate for the intrinsic electron-deficiency of boron atom. Herein, heterogeneous-structured MoB2 (h-MoB2) with amorphous shell and crystalline core, is prepared by solid phase molten salt method. As demonstrated, crystalline core can encapsulate the honeycomb borophene within two adjacent Mo atoms, and amorphous shell can accommodate more lithium ions to strengthen the lithium storage capacity and diffusion kinetics. According to theoretical calculations, the lithium adsorption energy in MoB2 is about -2.7 eV, and the lithium diffusion energy barrier in MoB2 is calculated to be 0.199 eV, guaranteeing the enhanced adsorption capability and fast diffusion kinetic behavior of Li+ ions. As a result, h-MoB2 anode presents high capacity of 798 mAh g-1 at 0.1 A g-1, excellent rate performance of 183 mAh g-1 at 5 A g-1 and long-term cyclic stability for 1200 cycles. This work may inspire ideas for the fabrication of borophene analogs and two-dimensional metal borides.

Ultrafast Knock-Off Li+ Diffusion and Subtle Structural Evolution of Li5V3O8 Anode in Lithium-Ion Batteries

Li5V3O8, a lithiation product derived from the LiV3O8 cathode, has emerged as a promising intercalation-type anode material, boasting a theoretical capacity of 256 mA h g-1. Through a comprehensive combination of experimental and theoretical approaches, we demonstrate its capability to intercalate a substantial amount of Li+ at extremely high rates. Experimental findings reveal that Li5V3O8 exhibits outstanding high-rate capability (with a specific capacity of 152 mA h g-1, 60% of the theoretical capacity at 40 C) and exceptional cyclability (with a capacity retention of 80% after 11,000 cycles at 20 C). The structural changes in Li5V3O8 during the lithiation/delithiation cycles are subtle and reversible. First-principles calculations highlight a knock-off mechanism in Li+ diffusion within Li5V3O8, with an estimated energy barrier ranging from 0.16 to 0.38 eV, considerably lower than that of a direct hopping mechanism (0.62-1.44 eV). These ultrafast ion diffusion properties are attributed to interlock interactions among interstitial tetrahedral Li+ and neighboring octahedral lattice Li+, facilitating long-distance and chain-like Li+ diffusion. This study not only introduces an influential vanadium-based anode material with practical implications for fast-charging lithium-ion batteries but also provides fundamental insights into solid state Li+ diffusion kinetics.

Laser-driven ultrafast impedance spectroscopy for measuring complex ion hopping processes

Superionic conductors, or solid-state ion-conductors surpassing 0.01 S/cm in conductivity, can enable more energy dense batteries, robust artificial ion pumps, and optimized fuel cells. However, tailoring superionic conductors requires precise knowledge of ion migration mechanisms that are still not well understood due to limitations set by available spectroscopic tools. Most spectroscopic techniques do not probe ion hopping at its inherent picosecond timescale nor the many-body correlations between the migrating ions, lattice vibrational modes, and charge screening clouds-all of which are posited to greatly enhance ionic conduction. Here, we develop an ultrafast technique that measures the time-resolved change in impedance upon light excitation, which triggers selective ion-coupled correlations. We also develop a cost-effective, non-time-resolved laser-driven impedance method that is more accessible for lab-scale adoption. We use both techniques to compare the relative changes in impedance of a solid-state Li+ conductor Li0.5La0.5TiO3 (LLTO) before and after UV to THz frequency excitations to elucidate the corresponding ion-many-body-interaction correlations. From our techniques, we determine that electronic screening and phonon-mode interactions dominate the ion migration pathway of LLTO. Although we only present one case study, our technique can extend to O2-, H+, or other charge carrier transport phenomena where ultrafast correlations control transport. Furthermore, the temporal relaxation of the measured impedance can distinguish ion transport effects caused by many-body correlations, optical heating, correlation, and memory behavior.

Stable cycling and low-temperature operation utilizing amorphous carbon-coated graphite anodes for lithium-ion batteries

With the continuous expansion of the lithium-ion battery market, addressing the critical issues of stable cycling and low-temperature operation of lithium-ion batteries (LIBs) has become an urgent necessity. The high anisotropy and poor kinetics of pristine graphite in LIBs contribute to the formation of precipitated lithium dendrites, especially during rapid charging or low-temperature operation. In this study, we design a graphite coated with amorphous carbon (GC) through the Chemical Vapor Deposition (CVD) method. The coated carbon layer at the graphite interface exhibits enhanced reaction kinetics and expanded lithium-ion diffusion pathways, thereby reduction in polarization effectively alleviates the risk of lithium precipitation during rapid charging and low-temperature operation. The pouch cell incorporating GC‖LiCoO2 exhibits exceptional durability, retaining 87% of its capacity even after 1200 cycles at a high charge/discharge rate of 5C/5C. Remarkably, at -20 °C, the GC-2 maintains a specific capacity of 163 mA h g-1 at 0.5C, higher than that of pristine graphite (65 mA h g-1). Even at -40 °C, the GC-2‖LiCoO2 pouch cell still shows excellent capacity retention. This design realizes the practical application of graphite anode in extreme environments, and have a promising prospect of application.

Surface and Bulk Stabilization of Silicon Anodes with Mixed-Multivalent Additives: Ca(TFSI)2 and Mg(TFSI)2

Silicon is drawing attention as an emerging anode material for the next generation of lithium-ion batteries due to its higher capacity compared with commercial graphite. However, silicon anions formed during lithiation are highly reactive with binder and electrolyte components, creating an unstable SEI layer and limiting the calendar life of silicon anodes. The reactivity of lithium silicide and the formation of an unstable SEI layer are mitigated by utilizing a mixture of Ca and Mg multivalent cations as an electrolyte additive for Si anodes to improve their calendar life. The effect of mixed salts on the bulk and surface of the silicon anodes was studied by multiple structural characterization techniques. Ca and Mg ions in the electrolyte formed relatively thermodynamically stable quaternary Li-Ca-Mg-Si Zintl phases in an in situ fashion and a more stable and denser SEI layer on the Si particles. These in turn protect silicon particles against side reactions with electrolytes in a coin cell. The full cell with the mixed cation electrolyte demonstrates enhanced calendar life performance with lower measured current and current leakage in comparison to that of the baseline electrolyte due to reduced side reactions. Electron microscopy, HR-XRD, and solid-state NMR results showed that electrodes with mixed cations tended to have less cracking on the electrode surface, and the presence of mixed cations enhances cation migration and formation of quaternary Zintl phases stabilizing the bulk and forming a more stable SEI in comparison to baseline electrolyte and electrolyte with single multivalent cations.

Zero-Strain Sodium Lanthanum Titanate Perovskite Embedded in Flexible Carbon Fibers as a Long-Span Anode for Lithium-Ion Batteries

"High-capacity" graphite and "zero-strain" spinel Li4Ti5O12 (LTO) occupy the majority market of anode materials for Li+ storage in commercial applications. Nevertheless, their intrinsic drawbacks including the unsafe potential of graphite and unsatisfactory capacity of LTO limit the further development of lithium-ion batteries (LIBs), which is unable to satisfy the ever-increasing demands. Here, a novel Na0.35La0.55TiO3 perovskite embedded in multichannel carbon fibers (NLTO-NF) is rationally designed and synthesized through an electrospinning method. It not only has the advantages of a respectable specific capacity of 265 mAh g-1 at 0.1 A g-1 and superb rate capability, but it also possesses the zero-strain characteristic. Impressively, an ultralong cycling life with 96.3% capacity retention after 9000 cycles at 2 A g-1 is achieved in the half cell, and 90.3% of capacity retention ratio is obtained after even 2500 cycles at 1 A g-1 in the coupled LiFePO4/NLTO-NF full cell. This study introduces a new member with excellent performance to the zero-strain materials family for next-generation LIBs.

Enhancing Fast-Charge Capabilities in Solid-State Lithium Batteries through the Integration of High Li0.5La0.5TiO3 (LLTO) Content in the Lithium-Metal Anode

Solid-state batteries (SSBs), which have high energy density and are safe, are recognized as an important field of study. However, the poor interfacial contact with high resistance, the dendrite problem, and the volume change of the metallic lithium anode prevent the use of SSBs. Li0.5La0.5TiO3 (LLTO) particles and molten lithium were used to create a high-performance LLTO-Li composite lithium with a sequential ion-conducting phase. With garnet electrolytes, this lithium has better wettability and reduced surface tension. To compensate for the lithium depletion that occurs during stripping, the Li-Ti phase with a high ionic diffusion coefficient that forms in the anode can rapidly transport lithium from the bulk to the solid-state interface, ensuring tight interface contact, preventing the formation of gaps, and homogenizing the current and Li+ flux. The LLTO-Li| LLZTO| LLTO-Li symmetric cell exhibits a good cyclic stability of 1000 h at room temperature, a low interfacial resistance of 22 Ω cm2, and a high critical current density of 1.2 mA cm-2. Furthermore, fully built cells with a LiFePO4 cathode showed outstanding cycling performance, maintaining 95% of their capacity after 900 cycles at 1 C and 92% capacity retention after 100 cycles at 2 C.

Recent Progress and Future Prospects of Anions O-site Doped Perovskite Oxides in Electrocatalysis for Various Electrochemical Systems

With the rapid development of novel energy conversion and storage technologies, there is a growing demand for enhanced performance in a wide range of electrocatalysts. Perovskite oxides (ABO3 ) have caused widespread concerns due to their excellent electrocatalytic properties, low cost, stable and reliable performance. In recent years, the research on anion O-site doping of perovskite oxides has been a cynosure, which is considered as a promising route for enhancing performance. However, a systematic review summarizing the research progress of anion-doped perovskite oxides is still lacking. Therefore, this review mainly introduces the elements and strategies of various common anions doped at O-site of perovskite oxides, analyzes their influence on the physical and chemical properties of perovskites, and separately concludes their applications in electrocatalysis. This review will provide ideas and prospects for the development of subsequent anion doping strategies for high performance perovskite oxides.

Improving Low-temperature Performance and Stability of Na2 Ti6 O13 Anodes by the Ti-O Spring Effect through Nb-doping

Na2 Ti6 O13 (NTO) with high safety has been regarded as a promising anode candidate for sodium-ion batteries. In the present study, integrated modification of migration channels broadening, charge density re-distribution, and oxygen vacancies regulation are realized in case of Nb-doping and have obtained significantly enhanced cycling performance with 92 % reversible capacity retained after 3000 cycles at 3000 mA g-1 . Moreover, unexpected low-temperature performance with a high discharge capacity of 143 mAh g-1 at 100 mA g-1 under -15 °C is also achieved in the full cell. Theoretical investigation suggests that Nb preferentially replaces Ti3 sites, which effectively improves structural stability and lowers the diffusion energy barrier. What's more important, both the in situ X-ray diffraction (XRD) and in situ Raman furtherly confirm the robust spring effect of the Ti-O bond, making special charge compensation mechanism and respective regulation strategy to conquer the sluggish transport kinetics and low conductivity, which plays a key role in promoting electrochemical performance.

2D Layered Materials for Fast-Charging Lithium-Ion Battery Anodes

The development of electric vehicles has received worldwide attention in the background of reducing carbon emissions, wherein lithium-ion batteries (LIBs) become the primary energy supply systems. However, commercial graphite-based anodes in LIBs currently confront significant difficulty in enduring ultrahigh power input due to the slow Li+ transport rate and the low intercalation potential. This will, in turn, cause dramatic capacity decay and lithium plating. The 2D layered materials (2DLMs) recently emerge as new fast-charging anodes and hold huge promise for resolving the problems owing to the synergistic effect of a lower Li+ diffusion barrier, a proper Li+ intercalation potential, and a higher theoretical specific capacity with using them. In this review, the background and fundamentals of fast-charging for LIBs are first introduced. Then the research progress recently made for 2DLMs used for fast-charging anodes are elaborated and discussed. Some emerging research directions in this field with a short outlook on future studies are further discussed.

Decorating Phosphorus Anode with SnO2 Nanoparticles To Enhance Polyphosphides Chemisorption for High-Performance Lithium-Ion Batteries

Phosphorus has been regarded as one of the most promising next-generation lithium-ion battery anode materials, because of its high theoretical specific capacity and safe working potential. However, the shuttle effect and sluggish conversion kinetics hamper its practical application. To overcome these limitations, we decorated SnO₂ nanoparticles at the surface of phosphorus using an electrostatic self-assembly method, in which SnO₂ can participate in the discharge/charge reaction, and the Li₂O formed can chemically adsorb and suppress the shuttle of soluble polyphosphides across the separator. Additionally, the Sn/Li-Sn alloy can enhance the electrical conductivity of the overall electrode. Meanwhile, the similar volume changes and simultaneous lithiation/delithiation process in phosphorus and SnO₂/Sn are beneficial for avoiding additional particle damage near two-phase boundaries. Consequently, this hybrid anode exhibits a high reversible capacity of ∼1180.4 mAh g^-1 after 120 cycles and superior high-rate performance with ∼78.5% capacity retention from 100 to 1000 mA g^-1.

Double Perovskite La2 MnNiO6 as a High-Performance Anode for Lithium-Ion Batteries

Traditional lithium-ion batteries cannot meet the ever-increasing energy demands due to the unsatisfied graphite anode with sluggish electrochemical kinetics. Recently, the perovskite material family as anode attracts growing attention due to their advantages on specific capacity, rate capability, lifetime, and safety. Herein, a double perovskite La₂ MnNiO₆ synthesized by solid-state reaction method as a high-performance anode material for LIBs is reported. La₂ MnNiO₆ with an average operating potential of <0.8 V versus Li⁺ /Li exhibits a good rate capability. Besides, the Li|La₂ MnNiO₆ cells perform long cycle life without decay after 1000 cycles at 1C and a high cycling retention of 93% is observed after 3000 cycles at 6C. It reveals that this material maintains stable perovskite structure with cycling. Theoretical calculations further demonstrate the high electronic conductivity, low diffusion energy barrier, and structural stability of the lithiated La₂ MnNiO₆ . This study highlights the double perovskite type material as a promising anode for next-generation batteries.

Toward Smart Sensing by MXene

The Internet of Things era has promoted enormous research on sensors, communications, data fusion, and actuators. Among them, sensors are a prerequisite for acquiring the environmental information for delivering to an artificial data center to make decisions. The MXene-based sensors have aroused tremendous interest because of their extraordinary performances. In this review, the electrical, electronic, and optical properties of MXenes are first introduced. Next, the MXene-based sensors are discussed according to the sensing mechanisms such as electronic, electrochemical, and optical methods. Initially, biosensors are introduced based on chemiresistors and field-effect transistors. Besides, the wearable pressure sensor is demonstrated with piezoresistive devices. Third, the electrochemical methods include amperometry and electrochemiluminescence as examples. In addition, the optical approaches refer to surface plasmonic resonance and fluorescence resonance energy transfer. Moreover, the prospects are delivered of multimodal data fusion toward complicated human-like senses. Eventually, future opportunities for MXene research are conveyed in the new material discovery, structure design, and proof-of-concept devices.

High-Entropy Perovskites for Energy Conversion and Storage: Design, Synthesis, and Potential Applications

Perovskites have shown tremendous promise as functional materials for several energy conversion and storage technologies, including rechargeable batteries, (electro)catalysts, fuel cells, and solar cells. Due to their excellent operational stability and performance, high-entropy perovskites (HEPs) have emerged as a new type of perovskite framework. Herein, this work reviews the recent progress in the development of HEPs, including synthesis methods and applications. Effective strategies for the design of HEPs through atomistic computations are also surveyed. Finally, an outlook of this field provides guidance for the development of new and improved HEPs.

Perovskite-Type SrVO3 as High-Performance Anode Materials for Lithium-Ion Batteries

Perovskite-type oxides, characterized by excellent multifunctional physical and chemical properties, are widely used in ferroelectric, piezoelectric, energy conversion, and storage applications. It is shown here that the perovskite-type SrVO₃ can achieve excellent electrochemical performance as lithium-ion battery anodes thanks to its high electrically and ionically conductivity. Conducting additive-free SrVO₃ electrodes can deliver a high specific capacity of 324 mAh g^-1 at a safe and low average working potential of ≈0.9 V vs Li/Li⁺ together with excellent high-rate performance. A high areal capacity of ≈5.4 mAh cm^-2 is obtained using an ultrathick (≈120 μm) electrode. Moreover, the fully lithiated SrVO₃ electrode exhibits only 2.3% volume expansion that is explained by a simple solid-solution Li⁺ -storage mechanism, resulting in good cycling stability of the electrode. This study highlights the perovskite-type SrVO₃ as a promising Li⁺ -storage anode and provides opportunities for exploring a variety of perovskite oxides as next-generation metal-ion battery anodes.

Mo-Incorporated Magnetite Fe3 O4 Featuring Cationic Vacancies Enabling Fast Lithium Intercalation for Batteries

Transition metal oxides (TMOs) as high-capacity electrodes have several drawbacks owing to their inherent poor electronic conductivity and structural instability during the multi-electron conversion reaction process. In this study, the authors use an intrinsic high-valent cation substitution approach to stabilize cation-deficient magnetite (Fe₃ O₄ ) and overcome the abovementioned issues. Herein, 5 at% of Mo⁴⁺ -ions are incorporated into the spinel structure to substitute octahedral Fe³⁺ -ions, featuring ≈1.7 at% cationic vacancies in the octahedral sites. This defective Fe_2.93 ▫_0.017 Mo_0.053 O₄ electrode shows significant improvements in the mitigation of capacity fade and the promotion of rate performance as compared to the pristine Fe₃ O₄ . Furthermore, physical-electrochemical analyses and theoretical calculations are performed to investigate the underlying mechanisms. In Fe_2.93 ▫_0.017 Mo_0.053 O₄ , the cationic vacancies provide active sites for storing Li⁺ and vacancy-mediated Li⁺ migration paths with lower energy barriers. The enlarged lattice and improved electronic conductivity induced by larger doped-Mo⁴⁺ yield this defective oxide capable of fast lithium intercalation. This is confirmed by a combined characterization including electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT) and density functional theory (DFT) calculation. This study provides a valuable strategy of vacancy-mediated reaction to intrinsically modulate the defective structure in TMOs for high-performance lithium-ion batteries.

Atomic Defect Mediated Li-Ion Diffusion in a Lithium Lanthanum Titanate Solid-State Electrolyte

Lithium lanthanum titanium oxide (LLTO) as a fast Li-ion conductor is a promising candidate for future all-solid-state Li batteries. Fundamental understanding of the microstructure of LLTO and its effect on the Li⁺ diffusion mechanism, especially across different length scales and interfaces, is a prerequisite to improving the material design and processing development of oxide-based solid electrolytes. Herein, through detailed structural analysis of LLTO ceramic pellets by aberration-corrected transmission electron microscopy, we discovered previously unreported intrinsic planar defects in LLTO single-crystal grains. These planar defects feature an antiphase boundary along specific crystal planes with a "rock-salt" structure enriched by Li within a few atomic layers. Corroborated by density-functional-theory-based calculations, we show an increased diffusion barrier across these planar defects inevitably lowers the bulk Li⁺ diffusivity of the oxide electrolyte.

Introducing a Pseudocapacitive Lithium Storage Mechanism into Graphite by Defect Engineering for Fast-Charging Lithium-Ion Batteries

The extreme fast-charging capability of lithium-ion batteries (LIBs) is very essential for electric vehicles (EVs). However, currently used graphite anode materials cannot satisfy the requirements of fast charging. Herein, we demonstrate that intrinsic lattice defect engineering based on a thermal treatment of graphite in CO₂ is an effective method to improve the fast-charging capability of the graphite anode. The activated graphite (AG) exhibits a superior rate capability of 209 mAh g^-1 at 10 C (in comparison to 15 mAh g^-1 for the pristine graphite), which is attributed to a pseudocapacitive lithium storage behavior. Furthermore, the full cell LiFePO₄||AG can achieve SOCs of 82% and 96% within 6 and 15 min, respectively. The intrinsic carbon defect introduced by the CO₂ treatment succeeds in improving the kinetics of lithium ion intercalation at the rate-determining step during lithiation, which is identified by the distribution of relaxation times (DRT) and density functional theory (DFT) calculations. Therefore, this study provides a novel strategy for fast-charging LIBs. Moreover, this facile method is also suitable for activating other carbon-based materials.

Atomic Short-Range Order in a Cation-Deficient Perovskite Anode for Fast-Charging and Long-Life Lithium-Ion Batteries

Perovskite-type oxides are widely used for energy conversion and storage, but their rate-inhibiting phase transition and large volume change hinder the applications of most perovskite-type oxides for high-rate electrochemical energy storage. Here, it is shown that a cation-deficient perovskite CeNb₃ O₉ (CNO) can store a sufficient amount of lithium at a high charge/discharge rate, even when the sizes of the synthesized particles are on the order of micrometers. At 60 C (15 A g^-1 ), corresponding to a 1 min charge, the CNO anode delivers over 52.8% of its capacity. In addition, the CNO anode material exhibits 96.6% capacity retention after 2000 charge-discharge cycles at 50 C (12.5 A g^-1 ), indicating exceptional long-term cycling stability at high rates. The excellent cycling performance is attributed to the formation of atomic short-range order, which significantly prevents local and long-range structural rearrangements, stabilizing the host structure and being responsible for the small volume evolution. Moreover, the extremely high rate capacity can be explained by the intrinsically large interstitial sites in multiple directions, intercalation pseudocapacitance, atomic short-range order, and cation-vacancy-enhanced 3D-conduction networks for lithium ions. These structural characteristics and mechanisms can be used to design advanced perovskite electrode materials for fast-charging and long-life lithium-ion batteries.

Low-Temperature Synthesis of Lithium Lanthanum Titanate/Carbon Nanowires for Fast-Charging Li-Ion Batteries

Due to the lower working voltage and higher capacity, the Li-rich lithium lanthanum titanate perovskite (LLTO) anode is becoming a potential candidate for the commercial Li₄Ti₅O₁₂ (LTO) Li-ion battery anode [Zhang, L. Lithium Lanthanum Titanate Perovskite as an Anode for Lithium Ion Batteries. Nat. Commun. 2020, 11, 3490]. However, a high temperature of 1250 °C is required to fabricate pure LLTO particles by the conventional solid-phase calcination method, limiting their further practical applications. Here, an in situ carbon nanospace confined method is developed to synthesize the pure LLTO with sub-nanometer grain size at an extremely low temperature of 800 °C. The LLTO precursor is confined in the in situ formed carbon nanowire matrix during heating, resulting in a shorter solid-phase diffusion distance and subsequently lower energy required for the formation of the pure LLTO phase. The low-temperature-synthesized pure LLTO/carbon composite nanowires (P-LLTO/C NWs) exhibit improved lithium storage performances than the traditionally prepared LLTO due to the fast electronic conduction of carbon and the stable carbon surface. In addition, the working potentials of P-LLTO/C||LiFePO₄ and P-LLTO/C||LiCoO₂ full cells are all 0.7 V higher than that of the corresponding commercial full cells with LTO as an anode, meaning much higher power energy densities (307.6 W kg^-1 at 2C and 342.4 W kg^-1 at 1C vs 198.4 W kg^-1 and 275.2 W kg^-1 for LTO||LiFePO₄ and LTO||LiCoO₂ full cells based on electrode materials, respectively). This low-temperature synthesis method can extend to other solid-state ionic materials and electrode materials for electrochemical devices.

Resource Availability and Implications for the Development of Plug-In Electric Vehicles

Plug-in electric vehicles (PEVs) have immense potential for reducing greenhouse gas emissions and dependence on fossil fuels, and for smart grid applications. Although a great deal of research is focused on technological limitations that affect PEV battery performance targets, a major and arguably equal concern is the constraint imposed by the finite availability of elements or resources used in the manufacture of PEV batteries. Availability of resources, such as lithium, for batteries is critical to the future of PEVs and is, therefore, a topic that needs attention. This study addresses the issues related to lithium availability and sustainability, particularly supply and demand related to PEVs and the impact on future PEV growth. In this paper, a detailed review of the research on lithium availability for PEV batteries is presented, key challenges are pinpointed and future impacts on PEV technology are outlined.

Mo6+–P5+ co-doped Li2ZnTi3O8 anode for Li-storage in a wide temperature range and applications in LiNi0.5Mn1.5O4/Li2ZnTi3O8 full cells

LZM7TP3O co-doped with Mo6+ and P5+, with excellent electrochemical performance at 0–55 °C, has been synthesized using a simple solid-state method. The LiNi0.5Mn1.5O4/LZM7TP3O full cell can power LED bulbs that emit different colors of light.

Two-dimensional Layered Lithium Lanthanum Titanium Oxide/Graphene-like Composites as Electrodes for Lithium-Ion Batteries

Perovskite-structure (ABO3) Lithium Lanthanum Titanate (LixLa(2-x)/3TiO3, LLTO) is widely used in all solid state lithium ion batteries based on its high ionic conductivity. In this study, a two-dimensional LLTO nanosheet/graphene...

Role of Pairwise Reactions on the Synthesis of Li0.3La0.57TiO3 and the Resulting Structure-Property Correlations

The performance of single-ion conductors is highly sensitive to the material's defect chemistry. Tuning these defects is limited for solid-state reactions as they occur at particle-particle interfaces, which provide a complex evolving energy landscape for atomic rearrangement and product formation. In this report, we investigate the (1) order of addition and (2) lithium precursor decomposition temperature and their effect on the synthesis and grain boundary conductivity of the perovskite lithium lanthanum titanium oxide (LLTO). We use an intimately mixed sol-gel, a solid-state reaction of Li precursor + La₂O₃ + TiO₂, and Li precursor + amorphous La_0.57TiO_x as different chemical routes to change the way in which the elements are brought together. The results show that the perovskite can accommodate a wide range of Li deficiencies (upward of 50%) while maintaining the tetragonal LLTO structure, indicating that X-ray diffraction (XRD) is insufficient to fully characterize the chemical nature of the product (i.e., Li-deficient LLTO may behave differently than stoichiometric LLTO). Variations in the relative intensities of different reflections in XRD suggest variations in the La ordering within the crystal structure between synthesis methods. Furthermore, the choice of the precursor and the order of addition of the reactants lower the time required to form a pure phase. Density functional theory calculations of the formation energy of possible reaction intermediates support the hypothesis that a greater thermodynamic driving force to form LLTO leads to a greater LLTO yield. The retention of lithium is correlated with the thermal decomposition temperature of the Li precursor and the starting material mixing strategy. Taking the results together suggests that cations that share a site with Li should be mixed early to avoid ordering. Such cation ordering inhibits Li motion, leading to higher Li ion resistance.

Defect engineering of oxide perovskites for catalysis and energy storage: synthesis of chemistry and materials science

Oxide perovskites have emerged as an important class of materials with important applications in many technological areas, particularly thermocatalysis, electrocatalysis, photocatalysis, and energy storage. However, their implementation faces numerous challenges that are familiar to the chemist and materials scientist. The present work surveys the state-of-the-art by integrating these two viewpoints, focusing on the critical role that defect engineering plays in the design, fabrication, modification, and application of these materials. An extensive review of experimental and simulation studies of the synthesis and performance of oxide perovskites and devices containing these materials is coupled with exposition of the fundamental and applied aspects of defect equilibria. The aim of this approach is to elucidate how these issues can be integrated in order to shed light on the interpretation of the data and what trajectories are suggested by them. This critical examination has revealed a number of areas in which the review can provide a greater understanding. These include considerations of (1) the nature and formation of solid solutions, (2) site filling and stoichiometry, (3) the rationale for the design of defective oxide perovskites, and (4) the complex mechanisms of charge compensation and charge transfer. The review concludes with some proposed strategies to address the challenges in the future development of oxide perovskites and their applications.

Introducing Oxygen Vacancies in Li4Ti5O12 via Hydrogen Reduction for High-Power Lithium-Ion Batteries

Li4Ti5O12 (LTO), known as a zero-strain material, is widely studied as the anode material for lithium-ion batteries owing to its high safety and long cycling stability. However, its low electronic conductivity and Li diffusion coefficient significantly deteriorate its high-rate performance. In this work, we proposed a facile approach to introduce oxygen vacancies into the commercialized LTO via thermal treatment under Ar/H2 (5%). The oxygen vacancy-containing LTO demonstrates much better performance than the sample before H2 treatment, especially at high current rates. Density functional theory calculation results suggest that increasing oxygen vacancy concentration could enhance the electronic conductivity and lower the diffusion barrier of Li+, giving rise to a fast electrochemical kinetic process and thus improved high-rate performance.

High-Performance-Based Perovskite-Supported Nanocomposite for the Development of Green Energy Device Applications: An Overview

Perovskite-based electrode catalysts are the most promising potential candidate that could bring about remarkable scientific advances in widespread renewable energy-storage devices, especially supercapacitors, batteries, fuel cells, solid oxide fuel cells, and solar-cell applications. This review demonstrated that perovskite composites are used as advanced electrode materials for efficient energy-storage-device development with different working principles and various available electrochemical technologies. Research efforts on increasing energy-storage efficiency, a wide range of electro-active constituents, and a longer lifetime of the various perovskite materials are discussed in this review. Furthermore, this review describes the prospects, widespread available materials, properties, synthesis strategies, uses of perovskite-supported materials, and our views on future perspectives of high-performance, next-generation sustainable-energy technology.