Li-air Research Articles

N, F Co-Doped Carbon Material Self-Supporting Cathode for High-Performance Lithium-Oxygen Batteries.

The Li-O2 battery has emerged as a promising energy storage system due to its exceptionally high theoretical energy density of 3500 Wh kg-1. However, the sluggish kinetics associated with the formation and decomposition of discharge product Li2O2 poses several challenges in Li-O2 batteries, including excessive over-potential, limited rate performance, and reduced actual specific energy. Consequently, the development of cost-effective cathode catalysts with enhanced catalytic activity and long-term stability represents a viable approach to address these challenges. In this study, commercial melamine foam is utilized as a precursor material which was subjected to pyrolysis at elevated temperatures with PVDF to synthesize N, F co-doped self-supporting carbon cathode (NF-NSC). Remarkably, thanks to the synergistic effects of N, F heteroatomic in conjunction with the inherent three-dimensional reticular porous structure, NF-NSC exhibited enhanced electrochemical performance when utilized in Li-O2 batteries. Specifically, the NF-NSC cathode demonstrated an impressive discharge specific capacity of up to 35204 mAh g-1 alongside a low over-potential (0.86 V) and excellent cycling stability (146 cycles).

A comprehensive review of carbon-based air cathode materials for advanced non-aqueous lithium–air batteries

A comprehensive review of carbon-based air cathode materials for advanced non-aqueous lithium–air batteries

Solid‐State Electrolytes for Lithium Metal Batteries: State‐of‐the‐Art and Perspectives

AbstractThe use of all‐solid‐state lithium metal batteries (ASSLMBs) has garnered significant attention as a promising solution for advanced energy storage systems. By employing non‐flammable solid electrolytes in ASSLMBs, their safety profile is enhanced, and the use of lithium metal as the anode allows for higher energy density compared to traditional lithium‐ion batteries. To fully realize the potential of ASSLMBs, solid‐state electrolytes (SSEs) must meet several requirements. These include high ionic conductivity and Li+ transference number, smooth interfacial contact between SSEs and electrodes, low manufacturing cost, excellent electrochemical stability, and effective suppression of dendrite formation. This paper delves into the essential requirements of SSEs to enable the successful implementation of ASSLMBs. Additionally, the representative state‐of‐the‐art examples of SSEs developed in the past 5 years, showcasing the latest advancements in SSE materials and highlighting their unique properties are discussed. Finally, the paper provides an outlook on achieving balanced and improved SSEs for ASSLMBs, addressing failure mechanisms and solutions, highlighting critical challenges such as the reversibility of Li plating/stripping and thermal runaway, advanced characterization techniques, composite SSEs, computational studies, and potential and challenges of ASS lithium–sulfur and lithium–oxygen batteries. With this consideration, balanced and improved SSEs for ASSLMBs can be realized.

Metal and Coordinating Atoms Synergistically Achieve High Activity and Stability in Single-Atom Catalysts within the Framework of TM-N3X for the Oxygen Evolution Reaction of Lithium Peroxide.

A critical challenge in the advancement of lithium-oxygen batteries (LOBs) is the difficulty in decomposing lithium peroxide, leading to high charge overpotentials and poor cycling stability. Single-atom catalysts (SACs), known for their ultrahigh catalytic activity in various electrochemical reactions, are expected to enhance the kinetics of the oxygen evolution reaction (OER) for LOBs. Herein, 24 SACs within the framework of TM-N3X have been designed and optimized for the OER of lithium peroxide. First-principles calculations reveal that the doped non-metal atom (X = B, C, O, or P) significantly contributes to the structural stability of the SACs while the metal atom (TM = Ru, Os, Rh, Ir, Pd, or Pt) significantly influences the catalytic activity of the SACs. Upon evaluation of their stability and catalytic activity, the Pt-N3B and Pd-N3B catalysts have been identified as promising candidates for the OER of lithium peroxide, with theoretical charge overpotentials of 0.19 and 0.18 V, respectively. This work provides new guidance for the design of efficient SACs for LOBs and inspires a fundamental understanding of the underlying structure-activity relationship.

Automated Robotic Cell Fabrication Technology for Stacked‐Type Lithium‐Oxygen Batteries

AbstractRechargeable lithium‐oxygen batteries (LOBs) are gaining interest as next‐generation energy storage devices due to their superior theoretical energy density. While recent years have seen successful operation of LOBs with high cell‐level energy density, the technology for cell fabrication is still in its infancy. This is because the cell fabrication procedure for LOBs is quite different from that of conventional lithium‐ion batteries. The study presents a fully automated sequential robotic experimental setup for the fabrication of stacked‐type LOB cells. This approach allows for high accuracy and high throughput fabrication of the cells. The developed system enables the fabrication of over 80 cells per day, which is 10 times higher than conventional human‐based experiments. In addition, the high alignment accuracy during the electrode stacking and electrolyte injection process results in improved battery performance and reproducibility. The effectiveness of the developed system was also confirmed by investigating a multi‐component electrolyte to maximize battery performance. We believe the methodology demonstrated in the present study is beneficial for accelerating the research and development of LOBs.

Tailoring Cationic Cobalt Vacancies in Molybdenum-Cobalt Selenide Derived from POM@ZIF-67 for Enhanced Electrocatalysis in Lithium-Oxygen Batteries.

Slow reaction kinetics during redox reactions limits the utilization of the high theoretical energy density of lithium-oxygen batteries (LOBs). Vacancy engineering, a potential strategy for modulating active sites, is critical in the development of high performance catalysts. This study investigates cobalt vacancies in Mo-CoSe2 nanoparticles created by selenization of phosphomolybdic acid (POM) embedded into zeolitic imidazolate framework-67 (ZIF-67). The nanomaterial exhibits an outstanding electrochemical performance, characterized by high specific capacitance and excellent cycle durability. The LOBs with cobalt vacancies in the Mo-CoSe2 electrode material exhibit a discharge capacity of 21 836 mAh g-1 at a current density of 100 mA g-1 and exhibit stable cycling performance over 194 cycles at 300 mA g-1. Additionally, density functional theory (DFT) calculations suggest that the presence of cobalt vacancies increases the distance between the surface selenium atoms and the subsurface cobalt atoms. In addition, cobalt vacancies modify the electronic structure of the d-orbitals, lowering the energy barriers of the reaction and accelerating the reaction kinetics by improving the adsorption of the reactants. The research introduces a strategy for the rational design of efficient cathode materials in LOBs.

Atomically dispersed Ir Lewis acid sites on (111)-oriented CeO2 enable enhanced reaction kinetics for Li-O2 batteries

Non-aqueous lithium-oxygen batteries are widely regarded as one of the most promising electrochemical energy storage systems, with their ultra-high theoretical energy density and environmental friendliness. However, the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics hinder their practical application. In this study, we tailored an atomically dispersed Ir site on a CeO2 support (Ir@CeO2) with {111} facet-dependent activity to enhance cathode reaction kinetics. The charge interaction between Ir and Ce atoms results in the appropriate regulation of the d-band center of Ir sites leaping into the Fermi energy level, demonstrating a stronger Lewis acidity, which enables easier electron injection from the Ir d-orbitals into O 2p-orbitals of LiO2. This facilitates the conversion kinetics, and as a result, the lithium-oxygen battery with Ir@CeO2 catalyst delivers a minimal discharge/charge polarization and long-term cycle stability, outperforming most traditional catalysts reported. Our promising findings offer compelling insights into the precise manipulation of d orbital structures and the optimization of Lewis acidity, paving the way for advanced electrocatalyst design.

Molecular Unravelling of the Structural Effect of Quinone Redox Mediators on Oxygen Reduction Reaction in Aprotic Lithium-Oxygen Batteries.

Redox mediators (RMs) provide tantalizing solutions to unlock the energy capabilities of aprotic lithium-oxygen (Li-O2) batteries by driving solution-mediated Li2O2 growth. However, the structural effect of RMs on the catalytic efficiency of the oxygen reduction reaction remains incompletely understood. Herein, we present the interplay between the structure of RMs and their discharge capabilities by a comparative study of model quinone (Q)-based RMs. Specifically, at low current densities, incorporating electron-withdrawing groups onto the Q ring can positively move the discharge potential and deliver larger discharge capacity by extending the lifespan of the LiQO2 intermediate and allowing for Li2O2 growth into deeper electrolyte regions. Conversely, at high current densities, the absence of electron-withdrawing groups facilitates homogeneous reaction kinetics from LiQ to regenerate Q (i.e., decreased lifespan of LiQO2), mitigating electrode potential polarization and preserving catalytic activity of Q for higher discharge capacity. The work establishes structure-property relationships that guide the rational design of RMs toward next-generation Li-O2 batteries.

P-Block-metal bismuth embedded in N/P co-doped carbon nanorods for kinetics-enhanced rechargeable lithium-oxygen batteries

Rechargeable lithium-oxygen batteries (LOBs) are considered one of the most promising electrochemical energy storage devices due to their extremely high theoretical energy density. However, the slow redox kinetics of the oxygen cathode leads to low coulombic efficiency and poor cycling performance, which limits the development of high-performance LOBs. Herein, Bi@NPC heterostructure nanorods are designed with the assistance of p-block metal Bi and successfully synthesized as bifunctional cathode catalysts for LOBs. Experimental and theoretical calculations show that Bi@NPC electrode can significantly reduce overpotential during discharge/charge processes due to the easily tunable localized p-orbitals and resulting versatile electronic structures. Benefiting from p-orbital electrons regulation of Bi atoms, the Bi@NPC electrode exhibited superior specific capacity over 11852.6 mAh g−1, outstanding rate capabilities, and ultralong cycle stability over 83 cycles at 200 mA g−1 with the fixed capacity of 500 mAh g−1. This work reveals an efficient pathway to synthesize p-block metal-based catalysts for high-performance LOBs.

Mutually Activated 2D Ti0.87O2/MXene Monolayers Through Electronic Compensation Effect as Highly Efficient Cathode Catalysts of Li–O2 Batteries

Abstract2D materials exhibit remarkable electrochemical performance as the cathode catalyst in lithium–oxygen batteries (LOBs). Their catalytic capability mainly derives from their 2D surface with tunable surface chemistry and unique electronic states. Herein, Ti0.87O2 and Ti3C2 MXene monolayers are applied to construct a face/face 2D heterostructure to enhance the catalytic performance in LOBs. It is demonstrated that electronic compensation from the O‐terminated MXene to Ti0.87O2 side is achieved through the built‐in electric field and the overlap of Ti 3d and O 2p orbitals between Ti0.87O2 and MXene units. As a result, the ORR/OER catalytic activity is improved in Ti0.87O2/MXene heterojunction due to the modulated p‐band center that optimizes the s–p coupling with the key intermediate LiO2. The Ti0.87O2/MXene cathode presents a structural stability and long‐term cycling life of 425 cycles (2534 h) at 200 mA g−1 and 407 cycles at 1000 mA g−1 with a fixed capacity of 600 mAh g−1, being nearly five and three times higher than that of pure Ti0.87O2 and MXene cathodes, respectively.

2D Microporous Polymers/Reduced Graphene Oxide with Built-In Lithiophilic Sites for Uniform Lithium Deposition in Lithium Metal Anode.

Lithium (Li) metal is an attractive anode material for use in high-energy lithium-sulfur and lithium-air batteries. However, its practical application is severely impeded by excessive dendrite growth, huge volume changes, and severe side reactions. Herein, a novel Li metal anode composed of lithiophilic two dimensional (2D) conjugated microporous polymer (Li-CMP) and reduced graphene oxide (rGO) sandwiches (Li-CMP@rGO) for Li metal batteries (LiMBs) is reported. In the Li-CMP@rGO anode, the conductive rGO facilitates the charge transfer while the functionalized-CMP provides Li nucleation sites within the micropores, thereby preventing dendrite growth. As a result, the Li-CMP@rGO anode can be cycled smoothly at 6mA cm-2 of current density with a platting capacity of 2 mAh cm-2 for 1000h. A Coulombic efficiency of 98.4% is achieved over 350 cycles with a low overpotential of 28mV. In a full cell with LiFePO4 cathode, the Li-CMP@rGO anode also exhibited good cycling stability compared to CMP@rGO and CMP/Super-P. As expected, the simulation results reveal that Li-CMP@rGO has a strong affinity for Li ions compared to CMP@rGO. The strategies adopted in this work can open new avenues for designing hybrid porous host materials for developing safe and stable Li metal anodes.

Anion-cation coupled electrolyte additive enhancing the performance of lithium-oxygen batteries

The rational design of electrolyte via introducing additive is an efficient strategy to improve the electrochemical performance of lithium-oxygen batteries (LOBs). In this work, coupling LiCl and Sn(TFSI)2 as the anion-cation electrolyte additive achieved the high-performance of LOBs by promoting the oxygen electrode reactions, regulating the Li+ solvation structure, and inducing the growth of the SEI protective layer. Specifically, Cl− with strong coordination affinity to Li+ could weaken the binding between Li+ and TEGDME solvent molecules, leading to the formation of an anion-dominant Li+ solvation structure, which facilitates the diffusion of Li+ in the electrolyte bulk and electrolyte/electrode interface. On the other hand, Sn2+ can serve as a redox mediator to catalyze ORR on the cathode and participate in the growth of smooth and dense SEI protective layer on Li metal anode surface, thus effectively promoting the oxygen electrode reaction kinetics and suppressing the corrosion of Li anode. As a consequence, the LOBs with coupled LiCl and Sn(TFSI)2 additive exhibited a ultra-high discharge capacity of 21517.1 mA h g−1 and an excellent cycling life of 334 cycles. This work provides a deep understanding for designing efficient electrolyte with additive for LOBs.

Mechanistic Analysis of Lithium-Air Battery with Organic Redox Mediator-Coated Air-Electrode

Redox mediators (RMs) suppress the charging overpotential to enhance the cycle performance of lithium-air batteries (LABs), but inappropriate RM incorporation can adversely shorten cycle life. In this study, three typical organic RMs; tetrathiafulvalene (TTF), 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO), and 10-methylphenothiazine (MPT), were incorporated into the air-electrode (AE) of the LAB (RM-on-AE), rather than dissolving them in the electrolyte (RM-in-EL), to maximize the RM effect throughout the cycle life. The discharge/charge cycle test confirmed that the cells with RM-on-AE prevented the reductive decomposition of RM with the lithium anode, deriving the RM effect for a longer cycle life than the cells with RM-in-EL. The measurement of AE deposits revealed that the TTF- and TEMPO-on-AE cells failed to generate a quantitative amount of Li2O2 discharge product. In contrast, the MPT-on-AE provided a 96% yield of Li2O2 after the first discharge because of the reductive tolerance of the MPT as organic RM. The quantitative analysis also revealed an accumulation of Li2CO3 on the AEs, along with the generation of carboxylate, as the side products of irrelevant battery reactions. This study provides a practical methodology for selecting RMs and their incorporation for developing long-life LABs.

Aligned Ion Conduction Pathway of Polyrotaxane-Based Electrolyte with Dispersed Hydrophobic Chains for Solid-State Lithium–Oxygen Batteries

HighlightsStrategic materials design of polyrotaxane-based electrolytes was suggested by aligning the ion conduction pathways and dispersing hydrophobic chains for solid-state Li–O2 batteries.Owing to intentional design, solid-state Li–O2 battery resulted in stable potential over 300 cycles at 25 °C.

Self-adaptive reconstructed high-entropy sulfide catalysts with optimized surface electronic structure for lithium-oxygen batteries

Self-adaptive reconstructed high-entropy sulfide catalysts with optimized surface electronic structure for lithium-oxygen batteries

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.