Li-air Batteries Research Articles

Li–O2/Air Batteries Using Ionic Liquids – A Comprehensive Review

AbstractThe remarkable surge in energy demand has compelled the quest for high‐energy‐density battery systems. The Li–O2 battery (LOB) and Li–air battery (LAB), owing to their extremely high theoretical energy density, have attracted extensive research in the past two decades. The commercial development of LOB is hampered due to the numerous challenges its components present. Ionic liquids (ILs) are considered potential electrolyte solvents of LOBs and LABs due to their excellent electrochemical stability, thermal stability, non‐flammability, low flammability, and O2 solubility. In addition to electrolyte solvents, ILs also have other applications in LOB and LAB systems. This review reports the progress of IL‐based LOBs and LABs over the years since treported for the first time in 2005. The impact of the physiochemical properties of ILs on the performance of LOB and LAB at various operating conditions is thoroughly discussed. The various methodologies are also summarized that are employed to tune ILs’ physiochemical properties to render them more favorable for rechargeable lithium batteries. Tunable properties of ILs create the possibility of designing cost‐effective batteries with excellent safety, high energy density and high power density, and long‐term stability.

Precise Engineering of Octahedron‐Induced Subcrystalline CoMoO4 Cathode Catalyst for High‐Performance Li–Air Batteries

AbstractLithium–air batteries (LABs) have attracted intense interest due to their ultrahigh energy density. However, the performance of LABs has to depend on modified electrolytes, gas selective film and Li anode protection. In this study, firstly it is reported that Mo‐O octahedron induced subcrystalline scheelite CoMoO4 catalyst achieves a high performance LABs performance based only on the high catalytic activity in air. The subcrystalline CoMoO4 catalyst obtains a specific capacity of 12 000 mAh g−1, and ultralong cycle stability over 270 cycles at 1000 mA g−1 in ambient air. This study demonstrates an ultrastable crystal structure and surface conditions of the CoMoO4 catalyst toward a corrosive environment and complex air‐involved reactions. A theoretical calculation further reveals that the polyhedral framework in the scheelite CoMoO4 can provide a highly stable catalytic surface for the OER/ORR reactions, furthermore, its repulsive nature toward H2O and CO2 can efficiently avoid side reactions and slow the corrosion of the Li anode in air. Moreover, the induced octahedron enhances the adsorption energies to O2 and LiO2, and accelerates the catalytic reactions in air. The present study provides a conceptual breakthrough to find highly active cathode catalysts for LABs.

Why charging Li-air batteries with current low-voltage mediators is slow and singlet oxygen does not explain degradation.

Although Li-air rechargeable batteries offer higher energy densities than lithium-ion batteries, the insulating Li2O2 formed during discharge hinders rapid, efficient re-charging. Redox mediators are used to facilitate Li2O2 oxidation; however, fast kinetics at a low charging voltage are necessary for practical applications and are yet to be achieved. We investigate the mechanism of Li2O2 oxidation by redox mediators. The rate-limiting step is the outer-sphere one-electron oxidation of Li2O2 to LiO2, which follows Marcus theory. The second step is dominated by LiO2 disproportionation, forming mostly triplet-state O2. The yield of singlet-state O2 depends on the redox potential of the mediator in a way that does not correlate with electrolyte degradation, in contrast to earlier views. Our mechanistic understanding explains why current low-voltage mediators (<+3.3 V) fail to deliver high rates (the maximum rate is at +3.74 V) and suggests important mediator design strategies to deliver sufficiently high rates for fast charging at potentials closer to the thermodynamic potential of Li2O2 oxidation (+2.96 V).

Lithium superoxide-based high rate Li-Air batteries enabled by Di-iridium sulfur bridge active sites

Li-oxygen (Li-O2) batteries can potentially provide much higher energy density than Li-ion batteries; however, the practical application of these batteries is hindered due to several drawbacks such as low current rates and high overpotential for the charging process. In this paper, we report a novel Li-Air battery system that operates under high current rates (up to 1mAcm−2) with LiO2 as the primary discharge product instead of the commonly reported Li2O2. This LiO2 based battery at high rates is through a combination of an as-synthesized new one-dimensional (1D) transition metal trichalcogenide mid-entropy alloy of SnIrS3.6 as a cathode catalyst and an electrolyte blend with a SnI2 bi-functional additive. It is revealed that SnIrS3.6 has a microporous structure composed of six- and five-coordinated metal atoms, forming octahedral and triangular bipyramids which has not been observed in other layered chalcogeide materials. DFT calculations reveal that the SnIrS3.6 structure can result in LiO2 formation through di-iridium sulfur bridge active sites that results in strong binding of O2 and LiO2 preventing disproportionation to Li2O2 and enabling high rates. This finding will open a new perspective in designing advanced LiO2-based Li-O2 batteries for real practices.

Gel electrolyte with dimethyl sulfoxide confined in a polymer matrix for Li-air batteries operable at sub-zero temperature

The instability of the electrolyte and insufficient ionic conductivity are considered the main problems that adversely affect applications of Li-air batteries (LABs) at sub-zero temperatures. In this study, a polymer-confined gel (PCG) electrolyte suitable for low-temperature LABs is developed by confining high donor number dimethyl sulfoxide (DMSO) within an in situ polymerized 4,4′-bis(stearoylamino)diphenyl ether (BSDE) matrix. The strong hydrogen bonds between the BSDE framework and DMSO molecules has destroyed the frozen structure of DMSO, thus the ionic conductivity at lower temperature has thus been improved. Furthermore, a local high-concentration electrolyte is constructed using DMSO as a solvent to dissolve the Li salt. The ionic conductivity of PCG in the fabricated electrolyte at −20 °C is maintained at 0.15 mS cm−1, which is 5.5 times higher than the corresponding liquid DMSO electrolyte. As a result, the LABs equipped with PCG display a long cycle life of 450 h (−20 °C) and 760 h (25 °C), whereas the LABs with a liquid DMSO electrolyte fail at −20 °C and can only operate for 40 h at 25 °C. This study provides a feasible but facile strategy for the design of gel electrolytes suitable for low-temperature LABs, and this strategy can be extended to other energy-storage systems.

Physical characteristics of nickel thin-films and nickel thin-film foams as Li-air batteries anode and cathode current collectors

Lithium-air batteries (LABs) are in the research and development stage between 2020 and 2030 as the future of lithium-ion batteries, and knowledge about their components provides the necessary data for commercializing. Current research investigates the physical characteristics of nickel (Ni) thin-films and Ni thin-film foams as anode and cathode current collectors, respectively, for LABs using the molecular dynamics simulation method. The obtained results provide helpful theoretical guidance for researchers to understand the physical attributes of current collectors and the interfacial interaction of air and electrolyte with cathode current collectors. Results indicate that the maximum service temperature of Ni thin-films and their foams with a 2.82–5.63 nm thickness equals 1200 and 1088 K, respectively, because the physical characteristics change significantly after these temperatures. Evaluation of the mechanical properties of Ni thin-films and their foams show that the mechanical attributes of these materials are in the acceptable region of current collectors. Therefore, Ni thin-films and their foams provide the required thermal and mechanical characteristics as anode and cathode current collectors, respectively. However, interfacial interaction between Ni thin-film foams with air and (CH3)2SO/LiPF6 non-aqueous electrolyte reveals that the presence of oxygen selective membrane is necessary for LABs cells. This membrane must not only block the flow of N2 and H2O toward the battery but also must impede the leakage of electrolytes. In addition, results depict that Ni thin-film foams have suitable applications as cathode current collectors for Li-N2 batteries due to more permeation depth of N2 molecules in comparison with other air molecules.

A Flexible Lithium-Ion-Conducting Membrane with Highly Loaded Titanium Oxide Nanoparticles to Promote Charge Transfer for Lithium-Air Battery.

In this research, we aim to investigate a flexible composite lithium-ion-conducting membrane (FC-LICM) consisting of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and titanium dioxide (TiO2) nanoparticles with a TiO2-rich configuration. PVDF-HFP was selected as the host polymer owing to its chemically compatible nature with lithium metal. TiO2 (40-60 wt%) was incorporated into the polymer matrix, and the FC-LICM charge transfer resistance values (Rct) were reduced by two-thirds (from 1609 Ω to 420 Ω) at the 50 wt% TiO2 loading compared with the pristine PVDF-HFP. This improvement may be attributed to the electron transport properties enabled by the incorporation of semiconductive TiO2. After being immersed in an electrolyte, the FC-LICM also exhibited a Rct that was lower by 45% (from 141 to 76 Ω), suggesting enhanced ionic transfer upon the addition of TiO2. The TiO2 nanoparticles in the FC-LICM facilitated charge transfers for both electron transfer and ionic transport. The FC-LICM incorporated at an optimal load of 50 wt% TiO2 was assembled into a hybrid electrolyte Li-air battery (HELAB). This battery was operated for 70 h with a cut-off capacity of 500 mAh g-1 in a passive air-breathing mode under an atmosphere with high humidity. A 33% reduction in the overpotential of the HELAB was observed in comparison with using the bare polymer. The present work provides a simple FC-LICM approach for use in HELABs.

A novel solid-state Li-air battery: from 2e− to 4e− O-redox reaction

A novel solid-state Li-air battery: from 2e− to 4e− O-redox reaction

Designing a hydrophobic PtCo/N-doped porous carbon catalyst for the long-term operation of Li–Air batteries in humid atmosphere

Li–air batteries with ultrahigh energy density are attracting attention, but at present, their practical applications are severely limited by water intrusion in the air. Herein, we loaded PtCo alloy nanoparticles on a N-doped porous carbon surface to create a novel hydrophobic functional catalyst. This catalyst effectively inhibited water contamination and suppressed the occurrence of side reactions. Li–air batteries with hydrophobic functional catalysts exhibited over double the cycle performance in both humid oxygen (∼50% relative humidity, over 255 h) and ambient air (CO2: 700 ppm, ∼55% relative humidity, over 135 h) at a current density of 500 mA g -1. In addition, the discharge specific capacities of humid oxygen and ambient air were increased to 18719.3 mAh g -1 and 11,385 mAh g -1.

Mechanistic Study of Solvent-Mediated Oxygen Reduction Reaction/Oxygen Evolution Reaction for Li-Air Battery Applications

Li-air batteries (LABs) have drawn growing interest to replace Li-ion batteries due to their extremely high theoretical energy density. However, the development of LABs is restricted majorly to designing air-cathode electrocatalysts and studying electrolyte properties such as conductivity and stability. Determining the effect of the explicit solvent environment on the electrochemical reactions taking place in LABs is important. Here, we have carried out the first principles thermodynamic study for LAB reactions (discharge and charge) on the Li2O2(100) cathode surface considering the effect of explicit dimethyl sulfoxide (DMSO) solvent. The mechanistic pathways and the thermodynamic overpotentials of LAB reactions are investigated. Furthermore, the effect of the explicit DMSO environment on the configurations of intermediate adsorptions resulting in changes in free energies is analyzed. The toroid-like nature of subsequent Li2O2 growth in the considered model is also proposed. An improved overpotential of discharging (0.52 V) for the considered system is reported, signifying the importance of considering the surface–solvent interphase model to study LAB reactions closer to the experimental scenario.

In-Situ Transformation of Li-ABW Zeolites Based on Li-Geopolymer

Lithium batteries, as energy storage devices, are playing an increasingly important role in human society. As a result of the low safety of the liquid electrolyte in batteries, more attention has been paid to solid electrolytes. Based on the application of lithium zeolite in a Li-air battery, a non-hydrothermal conversed lithium molecular sieve was prepared. In this paper, in-situ infrared spectroscopy, together with other methods, was used to characterize the transformation process of geopolymer-based zeolite. The results showed that Li/Al = 1.1 and 60 °C were the best transformation conditions for the Li-ABW zeolite. On this basis, the geopolymer was crystallized after 50 min of reaction. This study proves that the formation of geopolymer-based zeolite occurs earlier than the solidification of the geopolymer and shows that the geopolymer is a good precursor for zeolite conversion. At the same time, it comes to the conclusion that the formation of zeolite will have an impact on the geopolymer gel. This article provides a simple preparation process for lithium zeolite, explores the preparation process and mechanism, and provides a theoretical basis for future applications.

High Areal Capacity, Long Cycle Life Li-Air Batteries Enabled by Nano/Micro Hierarchical Porous Cathode.

The limited cycle life of Li-air batteries (LABs) with high areal capacity remains the chief challenge that hinders their practical applications. Here, the study proposes a hierarchical porous electrode (HPE) design strategy, in which porous MnO nanoflowers are built into mesopore/macropore electrodes through a combination of chemical dealloying and physical de-templating procedures. The MnO nanoflowers with 10-30nm pore provides active sites to catalyze the O2 reduction and decomposition of discharged products. The 5-10µm macroscopic pores in the cathode serve as channels of O2 transportation and facilitate the electrolyte permeation. The proposed HPE exhibits a full discharge capacity of 17.49mAhcm-2 and stable cycle life >2000h with a limited capacity of 6mAhcm-2 . These results suggest that the HPE design strategy for LABs can simultaneously provide large capacity and robust cycle life, which is promising for advanced metal-air batteries.

Rechargeable non-aqueous lithium-O2 batteries: Novel bimetallic (Ni-Cu) conductive coordination polymer cathodes

The development of highly efficient catalysts for the reactions of oxygen reduction (ORR) and oxygen evolution (OER) is crucial for lithium-O2 (Li-O2) batteries. Herein is synthesized a π-d conjugated bimetallic coordination polymer (NiCu-BTA) by the aid of the chemical deposition method and applied as cathode catalyst for Li-O2 batteries. Due to the difference in the electronic structures of Ni and Cu, the degree-disorder and porosity of NiCu-BTA increased compared with the pure Ni-BTA and Cu-BTA, resulting in an enhanced electrocatalytic activity and battery performance. At a current density of 100 mA g−1, the Li-air battery equipped with NiCu-BTA shows a discharge specific capacity of 23,000 mAh g−1 and can be consistently cycled up to 113 times. The tunable catalytic activity in M-BTA opens a new window for the design of low-cost and multifunctional catalysts, and may find potential applications in clean and renewable energy fields.

Addressing Transport Issues in Non-Aqueous Li–air Batteries to Achieving High Electrochemical Performance

Addressing Transport Issues in Non-Aqueous Li–air Batteries to Achieving High Electrochemical Performance

Solid‐state Li–air batteries: Fundamentals, challenges, and strategies

AbstractThe landmark Net Zero Emissions by 2050 Scenario requires the revolution of today's energy system for realizing nonenergy‐related global economy. Advanced batteries with high energy density and safety are expected to realize the shift of end‐use sectors toward renewable and clean sources of electricity. Present Li‐ion technologies have dominated the modern energy market but face with looming challenges of limited theoretical specific capacity and high cost. Li–air(O2) battery, characterized by energy‐rich redox chemistry of Li stripping/plating and oxygen conversion, emerges as a promising “beyond Li‐ion” strategy. In view of the superior stability and inherent safety, a solid‐state Li–air battery is regarded as a more practical choice compared to the liquid‐state counterpart. However, there remain many challenges that retard the development of solid‐state Li–air batteries. In this review, we provide an in‐depth understanding of fundamental science from both thermodynamics and kinetics of solid‐state Li–air batteries and give a comprehensive assessment of the main challenges. The discussion of effective strategies along with authoritative demonstrations for achieving high‐performance solid‐state Li–air batteries is presented, including the improvement of cathode kinetics and durability, solid electrolyte design, Li anode optimization and protection, as well as interfacial engineering.

Li-N2 Battery for Ammonia Synthesis and Computational Insight.

Electrochemical synthesis of ammonia is deemed as an alternative to the fossil-fuel-driven Haber-Bosch (HB) process, in which Li-mediated nitrogen reduction (LiNR) is the most promising scheme. Continuous lithium-mediated nitrogen reduction for ammonia synthesis (C-LiNR) has recently been reported in high-level journals with many foggy internal reactions. Synthesizing ammonia in a separate way may be profitable for understanding the mechanism of LiNR. Herein, an intermittent lithium-mediated nitrogen reduction for ammonia synthesis (I-LiNR) was proposed, three steps required for I-LiNR were achieved in the cathode chamber of a Li-N2 battery. Discharge, stand, and charge in the Li-N2 battery correspond to N2 lithification, protonation, and lithium regeneration, respectively. It can also realize the quasi-continuous process with practical significance because it could be carried out through identical batteries. Products such as Li3N, LiOH, and NH3 are detected experimentally, which demonstrate a definite reaction pathway. The mechanism of the Li-N2 battery, the Li-mediated synthesis of ammonia, and LiOH decomposition are explored through density functional theory calculations. The role of Li in dinitrogen activation is highlighted. It expands the range of LiOH-based Li-air batteries and may guide the study from Li-air to Li-N2; attention has been given to the reaction mechanism of Li-mediated nitrogen reduction. The challenges and opportunities of the procedure are discussed in the end.

Reversible Discharge Products in Li-Air Batteries.

Lithium-air (Li-air) batteries stand out among the post-Li-ion batteries due to their high energy density, which has rapidly progressed in the past years. Regarding the fundamental mechanism of Li-air batteries that discharge products produced and decomposed during charging and recharging progress, the reversibility of products closely affects the battery performance. Along with the upsurge of the mainstream discharge products lithium peroxide, with devoted efforts to screening electrolytes, constructing high-efficiency cathodes, and optimizing anodes, much progress is made in the fundamental understanding and performance. However, the limited advancement is insufficient. In this case, the investigations of other discharge products, including lithium hydroxide, lithium superoxide, lithium oxide, and lithium carbonate, emerge and bring breakthroughs for the Li-air battery technologies. To deepen the understanding of the electrochemical reactions and conversions of discharge products in the battery, recent advances in the various discharge products, mainly focusing on the growth and decomposition mechanisms and the determining factors are systematically reviewed. The perspectives for Li-air batteries on the fundamental development of discharge products and future applications are also provided.

2D MoSi2N4 as electrode material of Li-air battery — A DFT study

2D MoSi2N4 as electrode material of Li-air battery — A DFT study

Boosting the Bifunctional Oxygen Electrode Activity of Nitrogen-decorated Carbon Networks via Ni/NiO Addition for Li-Air and Zn-Air Batteries

Designing efficient and cost-effective oxygen electrode catalysts for metal-air batteries is the most intrinsic requisite for next-generation energy storage devices. In this work, bifunctional air-breathing electrode catalysts made of nitrogen-doped carbon (NC) and nickel/nickel oxide/nitrogen-doped carbon (NNONC) nanocomposites are explored for rechargeable Li-Air and Zn-Air batteries. The integration of Ni/NiO nanoparticles on the NC enhances the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities of the NC. Ni, nickel oxide, and NC acted synergistically to create additional reaction sites, high conductivity, and rapid diffusion pathways, resulting in increased catalytic activity. The CR-2032 coin-type and split cell Li-Air batteries were made with NNONC composite as cathode and Lithium metal as anode. The split cell had a high discharge capacity of 3330 mA h g−1 at a current density of 100 mA g−1. Moreover, the NNONC used as bifunctional cathode catalyst in the rechargeable Zn-Air battery. Where Anode is made of zinc-can from a used zinc carbon battery. The Zn-Air battery has good electrochemical activity, such as good cycle life and low overpotentials of 0.31 and 0.19 V for charging and discharging, respectively. Thus, NNONC can be a promising bifunctional catalyst for both the non–aqueous and aqueous rechargeable metal–air batteries.

A leap by the rise of solid-state electrolytes for Li-air batteries

Li-air batteries have attracted extensive attention because of their ultrahigh theoretical energy density. However, the potential safety hazard of flammable organic liquid electrolytes hinders their practical applications. Replacing liquid electrolytes with solidstate electrolytes (SSEs) is expected to fundamentally overcome the safety issues. In this work, we focus on the development and challenge of solid-stateLi-air batteries (SSLABs). The rise of different types of SSEs, interfacial compatibility and verifiability in SSLABs are presented. The corresponding strategies and prospects of SSLABs are also proposed. In particular, combining machine learning method with experiment and in situ (or operando) techniques is imperative to accelerate the development of SSLABs.