Li-air Research Articles

Breaking the capacity bottleneck of lithium-oxygen batteries through reconceptualizing transport and nucleation kinetics

AbstractThe practical capacity of lithium-oxygen batteries falls short of their ultra-high theoretical value. Unfortunately, the fundamental understanding and enhanced design remain lacking, as the issue is complicated by the coupling processes between Li2O2 nucleation, growth, and multi-species transport. Herein, we redefine the relationship between the microscale Li2O2 behaviors and the macroscopic electrochemical performance, emphasizing the importance of the inherent modulating ability of Li+ ions through a synergy of visualization techniques and cross-scale quantification. We find that Li2O2 particle distributed against the oxygen gradient signifies a compatibility match for the nucleation and transport kinetics, thus enabling the output of the electrode’s maximum capacity and providing a basis for evaluating operating protocols for future applications. In this case, a 150% capacity enhancement is further achieved through the development of a universalizing methodology. This work opens the door for the rules and control of energy conversion in metal-air batteries, greatly accelerating their path to commercialization.

Predicting the Impact of Parameter Uncertainty on Model-Guided Li-O2 Cathode Design

Abstract Despite their high theoretical capacity, actual performance in lithium-oxygen (Li-O2) batteries is limited by sluggish transport and kinetic processes. Cathodes must provide ample surface area to host solid reduction products, but must also support species transport to access these surfaces. Numerous modeling studies therefore attempt to optimize cathode design by identifying microstructures to balance these two needs. However, model validation has historically relied on literature-sourced transport properties, which vary greatly between studies. In this work, we develop an open source, 1-D, continuum-scale Li-O2 battery model to examine the impact of electrolyte properties on predicted Li-O2 battery performance and design. Results demonstrate that O2 diffusion and solubility have the greatest impact on optimal design. Varying O2 diffusivity within the range of literature values surveyed led to maximum energy density variations of nearly 400%. These variations have a meaningful impact on the associated design conclusions: the optimal cathode porosity varied between 55 and 75%, depending on the O2 diffusivity. Moreover, the impact of advanced micrsotructures, such as graded cathode porosity, varies greatly with changes in electrolyte transport parameter estimates. As such, fundamental studies are required to accurately measure key electrolyte properties to enable numerical simulation as a guide to Li-O2 cathode design.

Modulating Coordination Environment of Cobalt-Based Spinel Octahedral Metal Sites to Boost Metal–Oxygen Bond Covalency for Reversible Lithium–Oxygen Batteries

Modulating Coordination Environment of Cobalt-Based Spinel Octahedral Metal Sites to Boost Metal–Oxygen Bond Covalency for Reversible Lithium–Oxygen Batteries

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).

Cobalt nanoclusters Deposit on Nitrogen-Doped graphene Sheets as bifunctional electrocatalysts for high performance lithium – Oxygen batteries

Rechargeable lithium-oxygen (Li-O2) batteries are being considered as the next-generation energy storage systems due to their higher theoretical energy density. However, the practical application of Li-O2 batteries is hindered by slow kinetics and the formation of side products during the oxygen reduction and evolution reactions on the cathode. These reactions lead to high overpotentials during charging and discharging. To address these challenges, we propose a simple ultrasonic method for synthesizing cobalt nanoclusters embedded in nitrogen-doped graphene nanosheets (GrZnCo) derived from metal-organic frameworks (MOFs). The resulting material, due to the retention of metallic cobalt structure, exhibits better electronic conductivity. Additionally, the GrZnCo catalyst shows vigorous catalytic activity, which can improve reaction kinetics and suppress side reactions, thus lowering the charging overpotential. We have investigated the impact of different catalyst compositions (GrZnCox; x = 1, 3, 5) by varying the amounts of cobalt and zinc. The optimum catalyst, GrZnCo3, contains high cobalt-N active components, graphitic-N, pyridinic-N, pyrrolic-N, and abundant defect structures, which enhance the electrochemical performance. The defect-rich GrZnCo3 catalyst enables Li-O2 batteries to achieve a high discharge capacity of 13500 mAh·g−1 at 50 mA·g−1 and a remarkable long-term cycling performance of over 400 cycles at 100 mA·g−1 with a limited capacity of 500 mAh·g−1. This work demonstrates an effective approach to fabricate cost-effective electrocatalysts for various energy storage systems.

Investigating the environmental impacts of lithium-oxygen battery cathode production: A comprehensive assessment of the effects associated with oxygen cathode manufacturing

Lithium-oxygen batteries offer remarkably high energy density compared to current lithium-ion batteries. The key to their electrochemical performance lies in the processes occurring at the air cathode. However, the complexity of these reactions, coupled with the by-products generated during discharge, can make the reaction process slow or impede their efficiency. This study evaluates the environmental impact of high-efficiency lithium-oxygen batteries cathodes, including titanium oxide composites, graphene-based composites and activated carbon-based composites, through a life cycle assessment across 18 impact categories using a cradle-to-gate approach with a functional unit of 25 kWh. Results show that active material production was the largest contributor to environmental impact, particularly Global Warming Potential. Among the evaluated cathodes, reduced graphene oxide/α-mnaganese oxide/palladium (rGO/α-MnO2/Pd) demonstrated the highest environmental impact, with a global warming potential of 1130.71 kg carbon dioxide from active material production, due to its energy-intensive synthesis and the use of chemicals like sulfuric acid, sodium borohydride, hydrochloric acid, and hydrogen peroxide. Additionally, the rGO/α-MnO2/Pd cathode had the highest Human Toxicity Potential and Ozone Depletion Potential. Batteries with graphene-based cathodes achieved a specific capacity of 7500 mAh.g-1, underscoring their performance potential while highlighting the need for more sustainable cathode manufacturing methods. These findings emphasize the environmental considerations necessary for large-scale lithium-oxygen batteries implementation.

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

Magnetic field and photon co-enhanced S-scheme MXene/In2S3/CoFe2O4 heterojunction for high-performance lithium-oxygen batteries

Under the spotlight for their potential to reduce over-potential, photo-assisted Li–O2 batteries still face a key challenge: the rapid recombination of photo-generated electron-hole pairs, which limits their efficiency. In this study, we address this limitation by designing a Li–O2 battery that integrates both photo and magnetic field assistance, using an S-scheme MXene/In2S3/CoFe2O4 heterojunction photocathode. This unique combination enhances visible light absorption and generates a strong built-in electric field, facilitating effective charge separation and boosting photocatalytic activity. During discharge, photo-generated electrons participate in the oxygen reduction reaction, while photo-induced holes contribute to the decomposition of discharge products during charging. Furthermore, the introduction of a magnetic field, confirmed through vibrating sample magnetometer, Mössbauer spectroscopy, X-ray absorption near edge structure, and cyclic voltammetry analyses, enhances electron-hole separation via Lorentz forces and spin–orbit coupling, accelerating the formation and decomposition of Li2O2. With this synergistic approach, the battery achieves a high specific capacity of 26500 mAh g−1, ultra-low oxygen reduction/evolution reaction over-potentials of 0.08 V/0.17 V, and a long cycle life of 2000 cycles with energy efficiency of 98.11 %. This work demonstrates the promising potential of combining photo and magnetic field effects to improve the electrochemical performance of Li–O2 batteries, opening new avenues for high-performance energy storage systems.

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.