Li-air Research Articles

Manipulating Electron Delocalization of Metal Sites via a High-Entropy Strategy for Accelerating Oxygen Electrode Reactions in Lithium-Oxygen Batteries.

High-entropy perovskite oxides, in which the B-type metal site of perovskite oxides (ABO3) is occupied by over five kinds of transition metal ions, show promising applications in energy storage and conversion fields. Herein, high-entropy perovskite oxides (LaSr(5TM)O3) composed of Cr, Mn, Fe, Co, and Ni at the B-type metal site are prepared as oxygen electrocatalysts for Li-O2 batteries. The presence of compressive strain in LaSr(5TM)O3 effectively regulates the 3d orbit occupancy of the active Co site (Co2+ → Co3+) and lifts the energy level of the Co d-band center, thus leading to enhanced adsorption toward the LiO2 intermediate on Co sites. Furthermore, the high electron-drawing capability of Cr sites ensures sufficient electron exchange and further strengthens the adsorption of LiO2. As expected, the Li-O2 battery with a LaSr(5TM)O3 electrode delivers a low overpotential (0.79 V) and superior cyclability (226 cycles). This study provides a meaningful strain strategy to improve the electrocatalytic activity of multicomponent oxides via fabricating high-entropy materials.

Ruthenium atoms anchored on oxygen-modified molybdenum disulfide with strong interfacial coupling as efficient and stable catalysts for lithium–oxygen batteries

Rechargeable non-aqueous lithium-oxygen batteries (LOBs) have garnered increasing attention owing to their high theoretical energy density. However, their slow cathodic kinetics hinder efficient battery reactions. Nanoscale catalysts can effectively enhance electrocatalytic activity and atomic utilization efficiency. However, the agglomeration of nanoscale catalysts (such as cluster and single atoms) during continuous discharge/charge cycles leads to decreased electrochemical performance and poor cyclic stability. Herein, the ruthenium (Ru) atomic sites anchored on an O-doped molybdenum disulfide (O-MoS2) catalyst (designated as Ru/O-MoS2) was fabricated using a facile impregnation and calcination method. Strong Ru-O coupling between Ru atoms and the O-MoS2 substrate optimizes the localized electronic structure, resulting in improved electrochemical performance and enhanced resistance to Ostwald ripening. When employed as a cathode catalyst for LOBs, Ru/O-MoS2 catalyst exhibits a high reversible specific capacity (18700.5 (±59.8) mAh g−1), good rate capability, and enhanced long-term stability (115 cycles, 1200 h). This study encourages facile and efficient strategies for the development of effective and stable electrocatalysts for use in LOBs.

Mechanistic Study on Oxygen Reduction Reaction in High-Concentrated Electrolytes for Aprotic Lithium-Oxygen Batteries.

Highly concentrated electrolytes (HCEs) have energized the development of high-energy-density lithium metal batteries by facilitating the formation of robust inorganic-derived solid electrolyte interfaces on the lithium anode. However, the oxygen reduction reaction (ORR) occurring on the cathode side remains ambiguous in HCE-based lithium-oxygen (Li-O2) batteries. Herein, we investigate the ORR mechanism in a highly concentrated LiTFSI-CH3CN electrolyte using ultra-microelectrode voltammetry coupled with in situ spectroscopies. It is found that, compared to the dilute electrolyte, the HCE prolongs the lifespan of superoxide intermediates and decelerates their migration rate to the bulk solution, resulting in a change in growth mode for the discharge product of Li2O2 from traditional two-dimensional film growth to surface three-dimensional expansion growth. This alteration reduces the cathode passivation and thus delivers the enhanced discharge capacity. Additionally, the HCE also increases the reaction energy barrier between superoxide and solvent molecules, thereby minimizing parasitic reactions and improving the cycle performance of Li-O2 batteries. Our study reveals the intricate interplay between electrolytes and oxygen intermediates and provides important insights into electrolyte chemistries for better Li-O2 batteries.

Achieving high capacity by controlling the size of Fe/Co-N-C(t) in the cathode of lithium-oxygen batteries

Two samples are synthesized in a bimetallic system of iron and cobalt using a Metal-Organic Framework (MOF). The duration of precursor addition to the reaction vessel is controlled to synthesize Fe/Co-N-C(10 h) and Fe/Co-N-C(At once). The structural properties of the samples are analyzed using XRD, Raman, FT-IR, SEM, TEM, BET, TGA and ICP. Electrochemical tests are performed to evaluate the activity of the prepared catalysts as lithium-oxygen battery cathode materials. The Fe/Co-N-C(At once) sample, with its larger surface area, shows a greater discharge capacity of 8670 mAhg-1 compared to the Fe/Co-N-C(10 h) sample, which has a discharge capacity of 8339 mAhg-1. However, the Fe/Co-N-C(10 h) sample has a larger electrochemical active surface area due to the presence of more metals in the MOF shell. This results in higher ORR/OER activity in an alkaline environment and greater stability (180 h) as a lithium-oxygen battery cathode compared to the Fe/Co-N-C(At once) sample, which exhibits stability for 90 h.

Polyacrylonitrile-blended polyethersulfone separator with greatly improved interface compatibility for lithium-oxygen battery

A novel polyacrylonitrile-blended/polyethersulfone (PES/PAN) separator was developed using the nonsolvent-induced phase separation (NIPS) method to improve the poor interfacial compatibility of Li-O2 batteries. Batteries assembled with the represented PES/PAN-2 separator exhibits significantly enhanced stability compared to the pristine PES separator. Its interfacial impedance (425.1 Ω) is one-fifth that of the pure PES separator (2018.1 Ω), while its ionic conductivity (0.70 mS cm−1) is nearly double that of the pristine PES (0.38 mS cm−1). With all these merits, the battery utilizing the PES/PAN-2 separator achieved excellent cycling performance of up to 80 cycles at 1000 mAh g−1, making it a superior choice for high-performance lithium-oxygen batteries.

NiO nanosheets constructing honeycomb porous catalyst as an effective oxygen adsorption interlayer support for high performance lithium-oxygen batteries

Lithium-oxygen (LiO2) batteries are considered as a novel energy storage system as a result of its outstanding energy density. However, the challenge of oxygen corrosion is still restricting the practical application in LiO2 batteries. Here, we successfully acquire the NiO nanosheets constructing honeycomb porous catalysts as an effective oxygen adsorption interlayer support for high-performance LiO2 batteries. Honeycomb porous structures can store more oxygen and the defects in the exterior of NiO nanosheets can furnish more Lewis acid sites and catalytic sites to bind more O2− as a Lewis base for absorbing O2. Consequently, NiO nanosheets constructing honeycomb porous catalysts as interlayer is loading on the glass fiber membrane separator for LiO2 batteries in order to protect the anode from oxygen corrosion. The interlayer with 1.0 mg/cm2 NiO loading rate per unit area shows the outstanding electrochemical performance at a fixed 500 mAh/g specific discharge capacity and 0.1 mA/cm2 current density for 106 cycles in the LiO2 battery. This work provides an effective strategy to protect the Li metal anode in LiO2 batteries, at the same time, proposes a novel view for the efficient modification of separator.

Harnessing 4f Electron Itinerancy for Integrated Dual-Band Redox Systems Boosts Lithium-Oxygen Batteries Electrocatalysis.

In-depth comprehension and manipulation of band occupation at metal centers are crucial for facilitating effective adsorption and electron transfer in lithium-oxygen battery (LOB) reactions. Rare earth elements play a unique role in band hybridization due to their deep orbitals and strong localization of 4felectrons. Herein, we anchor single Ce atoms onto CoO, constructing a highly active and stable catalyst with d-fa dual-band redox center. It is discovered that the itinerant behavior of 4felectrons introduces an enhanced spin-orbit coupling effect, which facilitates ideal σ/π bonding and flexible adsorption between the Ce/Co active sites and *O. Simultaneously, the injection of localized Ce 4felectrons strengthens the orbital bonding capacity of Co-O, effectively inhibits the dissolution of Co sites and improves the structural stability of the cathode material. Bracingly, the Ce1/CoO-based LOB exhibits an ultra-low charge-discharge polarization (0.46 V) and stable cyclic performance (1088 hours). This work breaks through the traditional limitations in catalyst activity and stability, providing new strategies and theoretical insights for developing high-performance LOBs powered by rare-earth elements.

Progress in Sealed Lithium–Oxygen Batteries Based on the Oxygen Anion Charge Compensation Mechanism

Progress in Sealed Lithium–Oxygen Batteries Based on the Oxygen Anion Charge Compensation Mechanism

Effect of electrolyte level on performance and mass transfer of non-aqueous lithium-oxygen battery

To accurately reveal the effect of electrolyte content on mass transfer within lithium-oxygen batteries and their discharge performance, this study utilizes computed tomography(CT) scanning technology and digital reconstruction methods to construct a geometric model of the lithium-oxygen battery cathode that is equivalent to the actual one. Based on the fundamental principles of mass transfer, fluid dynamics, and electrochemistry, a two-dimensional model for the discharge process of lithium-oxygen batteries is established. This model facilitates analysis of various parameters and their influencing factors, including the distribution of reaction products, pore structure, oxygen concentration distribution, battery performance, and overpotential, within the lithium-oxygen battery cathode. The research findings indicate that the deposition of reaction products alters the cathode structure and material transport; lower discharge current density and higher electrolyte levels are conducive to the dispersed deposition of reaction products, thereby reducing the deposition's resistance to internal mass transfer in the cathode.

Fast and scalable preparation of metal–organic coordination polymeric precursor for bifunctional electrocatalysts for high performance lithium–oxygen batteries

The Metal-organic coordination polymers (MOCPs) with structural and functional diversity are considered effective cathode materials for Lithium-oxygen batteries (LOBs). Conventional synthesis methods make it difficult to obtain large quantities of materials. Here, A highly active low-cost Co-decorated N-doped carbon oxygen cathode catalyst (Co–N–C) was synthesized using a fast and scalable method based on positive and negative charge coordination. Rapid synthesis of MOCPs depends on the addition of base sites. A theory of “Lewis’s base-assisted rapid synthesis” was proposed. Co-N-C as LOBs air cathode showed 150 cycles with 1000 mAh g-1 at 500 mA g-1. The fast and scalable synthesis method can provide a feasible strategy for large-scale production of oxygen electrocatalysts for LOBs.

Defect Engineering in CuS1- x Nanoflowers Enables Low-Overpotential and Long-Cycle-Life of Lithium-Oxygen Batteries.

The defect engineering is essential for the development of efficient cathode catalysts for lithium-oxygen batteries. Herein, CuS1 -x nanoflowers are fabricated by microwave hydrothermal method. Through theoretical and experimental analysis, the S vacancies are observed, which result in augmented charge around Cu, improved adsorption of LiO2, and reduced overpotential. On the one hand, the generated electronic defects cause the Fermi level to shift toward the conduction band, which enhances the electronic conductivity and ion transfer. On the other hand, the increased S vacancies provide a large number of Cu active sites, which increase the charge transfer from Cu to LiO2, which improves the stability of the intermediate adsorption. Interactively, CuS1- x catalyst obtains a capacity of 23,227 mAh g-1 and a cycle life of 225 at 500mA g-1. This work will be helpful for obtaining an efficient cathode catalyst by providing a deep understanding of vacancy modulation in advanced catalysts.

Performance and catalytic mechanism of CNTs/Ti3C2Tx MXene composite cathode for air-breathing hybrid lithium-air batteries

Hybrid lithium-air batteries (HLABs) have not been widely used due to high overpotential, low cycling, slow kinetic rate, and poor cathode catalytic performance. CNTs/Ti3C2Tx MXene composite material was first used as a cathode for HLABs. The cycling performance of batteries equipped with composite cathodes with different mass ratios is tested in an air environment. It is found that when the mass ratio is mCNTs:mTi3C2TxMXene=1:1, the cycling performance of the battery is the best, reaching 405 cycles, i.e., 1620 h of cyclic charging and discharging under fixed capacity. In deep discharge testing, when the mass ratio of the composite cathode is mCNTs:mTi3C2TxMXene=1:1, the battery exhibits extremely high specific capacity, with a maximum value of 22,092.91 mAh/g. The first principles calculate the catalytic mechanism of Ti3C2Tx MXene as the catalyst for HLABs, and the adsorption energy of oxygen on the surface of Ti3C2Tx MXene and ORR processes is calculated. The experiments and calculations confirm that Ti3C2Tx MXene is suitable as a cathode catalyst for HLABs.

Anionic Solvation Transition at Low Temperatures for Reversible Anodes in Lithium-Oxygen Batteries.

Li-O2 batteries provide a novel technology for electric energy storage due to their high energy density. However, the strong solvent coordination with Li+ at low temperatures impacts their performance and triggers irreversible interfacial reactions on the Li anode. Herein, cyclopentyl methyl ether (CME) is incorporated in a dimethoxyethane (DME)-based electrolyte to realize an anionic solvation transition at low temperatures in Li-O2 batteries. CME featuring a single O coordination site substitutes highly solvating DME in the first solvation sheath, and it induces more anion coordination to Li+ across the room- and low-temperature ranges. The low residence time of CME (66 ps at 25 °C, 382 ps at -40 °C.) in the solvation structures leads to the fast exchange of coordinated CME molecules with Li+ in comparison with DME and facilitates Li+ desolvation at low temperatures. The simultaneously generated inorganic-rich solid electrolyte interphase promotes Li+ transport to improve Li deposition and suppress Li dendrite formation. These enable the Li-O2 battery to present a good cycling stability of 110 cycles with a fixed capacity of 1000 mA h g-1 at -40 °C. This work paves the way for designing novel electrolytes in low-temperature batteries.

Stable Lithium Oxygen Batteries Enabled by Solvent-diluent Interaction in N,N-dimethylacetamide-based Electrolytes.

In the pursuit of next-generation ultrahigh-energy-density Li-O2 batteries, it is imperative to develop an electrolyte with stability against the strong oxidation environments. N,N-dimethylacetamide (DMA) is a recognized solvent known for its robust resistance to the highly reactive reduced oxygen species, yet its application in Li-O2 batteries has been constrained due to its poor compatibility with the Li metal anode. In this study, a rationally selected hydrofluoroether diluent, methyl nonafluorobutyl ether (M3), has been introduced into the DMA-based electrolyte to construct a localized high concentration electrolyte. The stable -CH3 and C-F bonds within the M3 structure could not only augment the fundamental properties of the electrolyte but also fortify its resilience against attacks from O2 - and 1O2. Additionally, the strong electron-withdrawing groups (-F) presented in the M3 diluent could facilitate coordination with the electron-donating groups (-CH3) in the DMA solvent. This intermolecular interaction promotes more alignments of Li+-anions with a small amount of M3 addition, leading to the construction of an anion-derived inorganic-rich SEI that enhances the stability of the Li anode. As a result, the Li-O2 batteries with the DMA/M3 electrolyte exhibit superior cycling performance at both 30 °C (359th) and -10 °C (120th).

Stable Lithium Oxygen Batteries Enabled by Solvent‐diluent Interaction in N,N‐dimethylacetamide‐based Electrolytes

AbstractIn the pursuit of next‐generation ultrahigh‐energy‐density Li−O2 batteries, it is imperative to develop an electrolyte with stability against the strong oxidation environments. N,N‐dimethylacetamide (DMA) is a recognized solvent known for its robust resistance to the highly reactive reduced oxygen species, yet its application in Li−O2 batteries has been constrained due to its poor compatibility with the Li metal anode. In this study, a rationally selected hydrofluoroether diluent, methyl nonafluorobutyl ether (M3), has been introduced into the DMA‐based electrolyte to construct a localized high concentration electrolyte. The stable −CH3 and C−F bonds within the M3 structure could not only augment the fundamental properties of the electrolyte but also fortify its resilience against attacks from O2− and 1O2. Additionally, the strong electron‐withdrawing groups (−F) presented in the M3 diluent could facilitate coordination with the electron‐donating groups (−CH3) in the DMA solvent. This intermolecular interaction promotes more alignments of Li+‐anions with a small amount of M3 addition, leading to the construction of an anion‐derived inorganic‐rich SEI that enhances the stability of the Li anode. As a result, the Li−O2 batteries with the DMA/M3 electrolyte exhibit superior cycling performance at both 30 °C (359th) and −10 °C (120th).

Robust oxygen adsorbent mediated oxygen redox reactions for high performance lithium-oxygen battery

Lithium-oxygen batteries (LOBs) have been widely studied because of their ultra-high energy density (∼3500 Wh kg−1). However, the reversibility and stability of LOBs are greatly limited by the sluggish kinetics of oxygen reduction/evolution reactions (ORR/OER) and severely parasitic reactions on oxygen electrodes. Electrolyte in LOBs plays an important role in the transport of reactive oxygen species and Li+, which greatly affects the kinetics and reversibility of the charging and discharging processes of batteries. In this work, perfluorooctane (PFO) is used as the additive in 1.0 M LiTFSI/TEGDEM electrolyte for LOBs to regulate the kinetics of oxygen electrode reactions. Due to the strong adsorption ability of PE toward oxygen, the oxygen concentration inside the electrolyte is greatly increased after the addition of PE. In addition, the PE-added electrolyte also exhibits superior electrochemical stability and is capable of triggering solution-mediated Li2O2 growth pathway during the discharge process of the LOBs. Therefore, with the increased oxygen concentration and the optimized electrode/electrolyte interface, the ORR/OER kinetics on the oxygen electrode is significantly promoted, which enables the LOBs with excellent energy efficiency and cycling life. This work provides a new idea for the design of oxygen-rich and high-performance electrolyte for lithium-oxygen batteries.

Hydrogen‐Bonded Organic Frameworks‐based Electrolytes with Controllable Hydrogen Bonding Networks for Solid‐State Lithium Batteries

AbstractThe lack of stable solid‐state electrolytes (SSEs) with high‐ionic conductivity and the rational design of electrode/electrolyte interfaces remains challenging for solid‐state lithium batteries. Here, for the first time, a high‐performance solid‐state lithium‐oxygen (Li−O2) battery is developed based on the Li‐ion‐conducted hydrogen‐bonded organic framework (LHOF) electrolyte and the HOF‐DAT@CNT composite cathode. Benefiting from the abundant dynamic hydrogen bonding network in the backbone of LHOF‐DAT SSEs, fast Li+ ion transport (2.2×10−4 S cm−1), a high Li+ transference number (0.88), and a wide electrochemical window of 5.05 V are achieved. Symmetric batteries constructed with LHOF‐DAT SSEs exhibit a stably cycled duration of over 1400 h with uniform deposition, which mainly stems from the jumping sites that promote a uniformly high rate of Li+ flux and the hydrogen‐bonding network structure that can relieve the structural changes during Li+ transport. LHOF‐DAT SSEs‐based Li−O2 batteries exhibit high specific capacity (10335 mAh g−1), and stable cycling life up to 150 cycles. Moreover, the solid‐state lithium metal battery with LHOF‐DAT SSEs endow good rate capability (129.6 mAh g−1 at 0.5 C), long‐term discharge/charge stability (210 cycles). The design of LHOF‐DAT SSEs opens an avenue for the development of novel SSEs‐based solid‐state lithium batteries.

Beyond Catalysts: Exploring Discharge Product Growth and Intrinsic Overpotential in Lithium-Oxygen Batteries.

The lithium-oxygen (Li-O2) battery, renowned for its exceptionally high theoretical energy density, is poised to revolutionize next-generation energy storage systems. However, its practical application depends on overcoming several challenges, particularly the high cathode overpotential, which significantly diminishes the battery's energy efficiency and durability. This study delves into the interactions at the cathode surface during oxygen reduction and evolution reactions (ORR/OER), extending the analysis beyond the initial reaction stages to encompass the extensive charge-discharge process. We introduce and define the concepts of intrinsic equilibrium potential and intrinsic overpotential, demonstrating that these critical parameters are predominantly influenced by the growth of discharge products, rather than the catalysts, thereby underscoring the inherent properties of the battery. This shift in focus from merely enhancing cathode catalysts to understanding and leveraging the intrinsic characteristics of the battery discharge process opens new avenues for optimizing and enhancing the performance of large-scale Li-O2 batteries. Furthermore, our findings indicate potential broader applications to other metal-oxygen systems, paving the way for the design of high-capacity, high-efficiency energy storage technologies.

CO2- tolerant CuFe2O4 as Bifunctional Electrocatalyst for Transition from Rechargeable Li-O2 to Li-CO2 Batteries

CO2-tolerant rechargeable Lithium-Air batteries are seen as a high-performing alternative to Li-ion batteries. They utilize O2 from the air, reducing it at the cathode to form lithium peroxide (Li2O2) during discharge which is then oxidized to form lithium-metal and freeing O2 during charging. Most of the present studies involve pure O2 as the cathode material instead of aerial O2, which has a stiff-challenge due to atmospheric CO2 which produces Li2CO3 during discharge, posing a resistive load on the battery if not re-oxidized on charging. Ideally, presence of CO2 should enhance the charge-storage capacity if it is cycled reversibly. Thus, present research aims at taking advantage of both O2 and CO2 by employing metallic Cu on CuFe2O4 catalyst, synthesized from a one-step auto-combustion route. The Cu metal present in the catalyst leads to a low surface-area, yet the catalyst demonstrates excellent oxygen reduction reaction and moderate oxygen evolution reaction activity. excellent CO2 reduction reaction activity, oxidizing both the Li2O2 and the Li2CO3 during charge in both 10% CO2 and 100% CO2 atmospheres. The fabricated Li-CO2 battery operates for practical application, suggesting the suitability of the catalyst for the transition from practical Li-O2 battery to Li-Air battery.

Recent Advances on Ruthenium-Based Electrocatalysts for Lithium-Oxygen Batteries

Recent Advances on Ruthenium-Based Electrocatalysts for Lithium-Oxygen Batteries