Performance Of Li-O2 Batteries Research Articles

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.

Ruthenium highly dispersed in low crystallinity cobalt oxide as an efficient catalyst for Li-O2 battery

The performance of Li-O2 battery can be improved by adjusting the reaction active sites of cathode catalysts. In this study, noble metal ruthenium (Ru) was successfully added to the framework of Zeolitic Imidazolate Framework-67 (ZIF-67) through a dual solvent method, and prepared highly dispersed noble metal ruthenium cathode catalyst material for Li-O2 battery. At the same time, the phenomenon of aggregation of precious metal ruthenium on the catalyst surface is avoided, and the atomic utilization rate of precious metals is improved. The low crystallinity cobalt oxide (ZIF-67-280) and noble metal ruthenium act as the catalytic active center together, enriching the reaction active sites of the catalyst, further improving the performance of Li-O2 battery and reducing the reaction overpotential. Compared to commercial cobalt oxides (C-Co3O4), ruthenium doped low crystallinity cobalt oxides (Ru@ZIF-67-280) has better cycle stability (272 cycles) and higher energy efficiency.© 2023 xxxxxxxx. Hosting by Elsevier B.V. All rights reserved.

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.

Rate-Dependent Formation Processes in Li-O2 Batteries: Phase-Field Modeling with the Marcus Kinetics

Lithium-oxygen batteries (Li-O2) present a compelling prospect for the next generation of batteries owing to their exceptionally high theoretical energy density.[1] Yet, the performance of Li-O2 batteries is significantly limited by the current-dependent morphology of insulating oxides.[2-3] Existing mathematical models using Butler-Volmer kinetics exhibit uncertainties and inaccuracies.[4-5] In this study, we propose the integration of Marcus kinetics with the existing phase-field model to resolve a few outstanding inconsistencies between theoretical predictions and experimental discoveries. Notably, utilizing the Marcus kinetics enables a quantitative assessment of the role of solvation energy in current-dependet particle growth as opposed to film growth. Experimental results further verify the new theoretical predictions. This research offers valuable insights for the future design of Li-O2 batteries.[1] Bruce, P. G., Freunberger, S. A., Hardwick, L. J., & Tarascon, J.-M. (2012). Nucleation and growth of lithium peroxide in the Li-O2 battery. Nature Materials, 11, 19–29.[2] Read, J. (2002). Characterization of the Lithium/Oxygen Organic Electrolyte Battery. Journal of The Electrochemical Society, 149, A1190-A1195.[3] Kraytsberg, A., & Ein-Eli, Y. (2011). Review on Li–air batteries—Opportunities, limitations and perspective. Journal of Power Sources, 196, 886-893.[4] Lau, S., & Archer, L. A. (2015). Nucleation and growth of lithium peroxide in the Li-O2 battery. Nano Letters, 15(9), 6108–6114.[5] Horstmann, B., Gallant, B., Mitchell, R., Bessler, W. G., Shao-Horn, Y., & Bazant, M. Z. (2013). Rate-dependent morphology of Li2O2 growth in Li-O2 batteries. Journal of Physical Chemistry Letters, 4(24), 4227–4232.

(Invited) Enhanced Catalysis of Surface-Activated Metallic WSe2 Nanosheets By Single-Atom Pt for High-Performance Li-O2 Battery

Layered materials, such as TMDCs, exhibit various electronic structures attributed to their polymorphism and can be further modificated at the atomic level through chemical treatments. TMDCs in the metallic phase (1T or 1T’ phase) have gained attention as efficient electrocatalystic materials, due to their exceptional transport properties compared to TMDCs in the semiconducting phase (2H phase). TMDCs with the metallic phase have been prepared by atomic-scale post-treatments, such as an intercalation and single-atom doping. However, the precise role of these post-treatments in the catalytic performance of TMDCs is still ambiguous, as it is uncertain whether the enhanced properties arise from charge transfer kinetics in metallic phase or electrochemical properties induced by the post-treatment.Herein, we present a straightforward approach fabrication for fabricating metallic WSe2 nanosheets, which serve as an excellent support for single-atom Pt doping. The incorporation of single-atom Pt into WSe2 nanosheets was achieved using a simple solution method at room temperature. Extensive measurements were conducted, including XAS, XPS, and XPDF to investigate the local coordination structure of Pt-WSe2. These measurements confirmed the presentce of single-atom Pt doping within WSe2 layers. The introduction of single-atom Pt significantly enhanced the kinetics of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), leading to improved performance of Li-O2 batteries. Experimental measurements and DFT calculations provided evidence that the enhanced catalytic abilities of Pt-WSe2 originated from the improved interaction between oxygen and the Se vacancy on basal planes of WSe2. Consequently, the Li-O2 battery incorporating the Pt-WSe2 catalyst exhibited a stable discharge and charge cycle for up to 350 cycles, demonstrating its superior durability.

Construct heterostructures of MoO3 nanorods modified with Fe2O3 rice grains to improve the performance of light-involved Li-O2 battery

Light-involved Li-O2 batteries have received widespread attention in recent years. However, slow reaction kinetics and high charge/discharge overpotentials at high current densities, as well as rapid recombination of photogenerated holes and electrons have hindered their further development. In this study, we propose a design strategy to grow Fe2O3 rice grains in situ on α-MoO3 nanorods to fabricate heterostructures for Li-O2 batteries at high current densities. The heterostructure α-MoO3@Fe2O3 serves as dual-function cathode catalysts for light-involved Li-O2 batteries by facilitating oxygen reduction/oxidation reactions and enhancing the separation of photogenerated charges, thereby effectively improving photoelectrocatalytic performance. Under light irradiation conditions, the heterostructure α-MoO3@Fe2O3 exhibits low charge/discharge overpotential (0.99 V) while demonstrating good cycling stability (stable cycling for 120 cycles at a high current density of 0.5 mA cm−2 with a fixed capacity of 0.5 mAh cm−2) and good rate performance, which significantly better than that was reported the currently popular light-involved Li-O2 batteries under a high current density.

Enhanced Li-O2 battery performance using NiS/MoS2 heterostructure by building internal electric field to promote the one-electron oxygen reduction/oxidation

Electrocatalysts with appropriate electron coupling toward LiO2 intermediates can exhibit superior oxygen reduction/evolution reaction kinetics in Li-O2 batteries (LOBs). In this work, a charge redistribution strategy has been developed by constructing NiS/MoS2 heterostructure nanosheet self-assembled hollow microspheres with an internal electric field to regulate the interaction with LiO2 and then improve the electrochemical performance of LOBs. Density functional theory calculations and physicochemical characterizations reveal that the difference of work functions between NiS and MoS2 promotes the electron redistribution in heterointerface via built-in electrical field, leading to increased electron density of interfacial Ni atom, thereby enhancing its electron coupling toward LiO2 intermediates and promoting one-electron oxygen reduction/oxidation reaction kinetics. As a result, the NiS/MoS2-based LOBs exhibit evidently higher discharge capacity and much better cycling performance than the batteries using NiS and MoS2. This work provides a reliable charge redistribution strategy induced by build-in electric field to design efficient catalysts for LOBs.

Probing interfacial stress on Au cathode in DMSO electrolyte during electrochemical polarization in aprotic Li-O2 batteries

The practical performance of Li-O2 batteries suffers from interfacial instabilities associated with the reaction intermediates. These instabilities on the cathode-electrolyte interface dictate the direction of the oxygen evolution and reduction reactions (OER/ORR) in Li-O2 batteries. Despite intensive research on chemical instabilities in the reaction intermediates, there is limited work on understanding the importance of stress on the interfacial dynamics. To address this gap, in-situ curvature measurements were conducted to probe interfacial stress generation during electrochemical polarization on Au cathode in DMSO electrolytes. Charge accumulation induces tensile stress, whereas compressive stress generation is associated with the adsorbate-induced stress and mismatch strain between reaction intermediates and the Au surface. Abrupt stress relaxation on the onset of discharge presents evidence for a contribution of electrostriction stress. Adsorption of redox mediator nitrate ions induces compressive stress before ORR. Unique findings demonstrate the impact of interfacial stress on the OER/ORR in Li-O2 batteries.

In situ construction of a P-doped TiO2/Ti3C2Tx heterostructure with local site optimization to improve Li-O2 battery performance

The performance of Li-O2 batteries is seriously limited by the sluggish kinetics of the mass transition in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). To explore a useful strategy to overcome these limitations, herein, we constructed a P-doped TiO2/Ti3C2Tx heterostructure (PTT) with local active site optimization, in which the highly conductive substrate anchored the P-TiO2 nanoparticles with a selective adsorption and conversion of LiOx. In contrast to the TiO2/Ti3C2Tx heterostructure with a relatively uniform active site inducing typical toroidal Li2O2, the introduction of P-doping generates a unique nanosheet array Li2O2 on the PTT surface as a discharge product. This unique structure is endowed with a shorter Li+ diffusion path and benefits mass transfer in ORR and OER, facilitating the reaction kinetics. It presents obviously enhanced battery performance with a high specific capacity of 13,482 mAh g−1 and decreased discharge–charge overpotential, as well as superior cycling stability of 190 cycles. Furthermore, this novel and efficient electrocatalyst can stably operate for more than 650 cycles at 1000 mA g−1 with the addition of a LiI redox mediator. This study provides new insight into high-performance electrocatalyst design in Li2O2 related battery system.

Constructing Built-In Electric Field in NiCo2O4-CeO2 Heterostructures to Regulate Li2O2 Formation Routes at High Current Densities.

Developing catalysts with suitable adsorption energy for oxygen-containing intermediates and elucidating their internal structure-performance relationships are essential for the commercialization of Li-O2 batteries (LOBs), especially under high current densities. Herein, NiCo2O4-CeO2 heterostructure with a spontaneous built-in electric field (BIEF) is designed and utilized as a cathode catalyst for LOBs at high current density. The driving mechanism of electron pumping/accumulation at heterointerface is studied via experiments and density functional theory (DFT) calculations, elucidating the growth mechanism of discharge products. The results show that BIEF induced by work function difference optimizes the affinity for LiO2 and promotes the formation of nano-flocculent Li2O2, thus improving LOBs performance at high current density. Specifically, NiCo2O4-CeO2 cathode exhibits a large discharge capacity (9546mAhg-1 at 4000mAg-1) and high stability (>430 cycles at 4000mAg-1), which are better than the majority of previously reported metal-based catalysts. This work provides a new method for tuning the nucleation and decomposition of Li2O2 and inspires the design of ideal catalysts for LOBs to operate at high current density.

The effect of water admixture on aprotic Mg-O2 battery performance

Generally, aprotic Li-O2 batteries performance is significantly influenced by water impurity in electrolyte/gas via promotion of Li2O2 mesocrystallization. In the case of promising alkali-earth metals this issue remains unexplored. Here we have studied the role of water content in DMSO-based electrolyte in discharge process of Mg-O2 cells with metallic magnesium anode and carbon cathode. We found that water impurity in the electrolyte is not a key factor determining the discharge capacity for a Mg-O2 battery, at least in a single-compartment cell. Morphology of discharge product does not change upon addition 8000 ppm of water. Discharge products contain major amount of electrolyte byproducts and negligible concentration of magnesium peroxide. Under high water content (more than 8000 ppm) Mg(OH)2 is also formed as discharge product, but content of by-products still remains high.

Regulating d-orbital electronic configuration of Ni-based chalcogenides to enhance the oxygen electrode reactions in Li-O2 batteries

Transition metal chalcogenides based electrocatalysts with regulable d-orbital electronic configuration by various chalcogen anions can exhibit excellent oxygen electrode reaction kinetics in Li-O2 batteries (LOBs). In this work, an electron rearrangement strategy to improve the catalytic activity of hexagonal NiS microsheets for LOBs has been developed via introducing Se anion as a substitution of S. With the as-prepared NiS0.67Se0.33 as cathode catalyst, LOB could achieve evidently lower overpotentials, larger discharge capacity, and ultralong cycling life than that using NiS. With the help of physicochemical techniques and theoretical calculations, the performance enhancement of NiS0.67Se0.33 could be elucidated with its suitable d-orbital electronic configuration. Specifically, Se anion substitution can modulate metal–chalcogen interactions with increased charge density and positively shifted d-band center of Ni metal cation, thereby promoting the d-p orbitals hybridization with increased binding strength to LiO2 intermediates and promoting oxygen reduction/evolution reaction kinetics. Moreover, small amount of Ni dissolution from NiS0.67Se0.33 to the electrolyte because of the rearranged electronic configuration also contributes to the enhanced oxygen electrochemistry and improved LOB performance by serving as a redox mediate catalyst. This work provides a facile anion doping engineering to facilitate the oxygen electrode reactions in LOBs by modulating d-orbital electronic configuration.

Exploring the Potential of Hierarchical Zeolite-Templated Carbon Materials for High-Performance Li-O2 Batteries: Insights from Molecular Simulations.

The commercialization of ultrahigh capacity lithium-oxygen (Li-O2) batteries is highly dependent on the cathode architecture, and a better understanding of its role in species transport and solid discharge product (i.e., Li2O2) formation is critical to improving the discharge capacity. Tailoring the pore size distribution in the cathode structure can enhance the ion mobility and increase the number of reaction sites to improve the formation of solid Li2O2. In this work, the potential of hierarchical zeolite-templated carbon (ZTC) structures as novel electrodes for Li-O2 batteries was investigated by using reactive force field molecular dynamics simulation (reaxFF-MD). Initially, 47 microporous zeolite-templated carbon morphologies were screened based on microporosity and specific area. Among them, four structures (i.e., RHO-, BEA-, MFI-, and FAU-ZTCs) were selected for further investigation including hierarchical features in their structures. Discharge product cluster analysis, self-diffusivities, and density number profiles of Li+, O2, and dimethyl sulfoxide (DMSO) electrolyte were obtained to find that the RHO-type ZTC exhibited enhanced mass transfer compared to conventional microporous ZTC (approximately 31% for O2, 44% for Li+, and 91% for DMSO) electrodes. This is due to the promoted formation of small-sized product clusters, creating more accessible sites for oxygen reduction reaction and mass transport. These findings indicate how hierarchical ZTC electrodes with micro- and mesopores can enhance the discharge performance of aprotic Li-O2 batteries, providing molecular insights into the underlying phenomena.

Coupling MoSe2 with Non-Stoichiometry Ni0.85 Se in Carbon Hollow Nanoflowers for Efficient Electrocatalytic Synergistic Effect on Li-O2 Batteries.

Li-O2 batteries could deliver ultra-high theoretical energy density compared to current Li-ion batteries counterpart. The slow cathode reaction kinetics in Li-O2 batteries, however, limits their electrocatalytic performance. To this end, MoSe2 and Ni0.85 Se nanoflakeswere decorated in carbon hollow nanoflowers, whichwere served as the cathode catalysts for Li-O2 batteries. The hexagonal Ni0.85 Se and MoSe2 show good structural compatibility with the same space group, resulting in a stable heterogeneous structure. The synergistic interaction of the unsaturated atoms and the built-in electric fields on the heterogeneous structure exposes abundant catalytically active sites, accelerating ion and charge transport and imparting superior electrochemical activity, including high specific capacities and stable cycling performance. More importantly, the lattice distances of the Ni0.85 Se (101) plane and MoSe2 (100) plane at the heterogeneous interfaces are highly matched to that of Li2 O2 (100) plane, facilitating epitaxial growth of Li2 O2 , as well as the formation and decomposition of discharge products during the cycles. This strategy of employing nonstoichiometric compounds to build heterojunctions and improve Li-O2 battery performance is expected to be applied to other energy storage or conversion systems.

A "Trinity" Design of Li-O2 Battery Engaging the Slow-Release Capsule of Redox Mediators.

Nonaqueous Li-O2 battery (LOB) represents one of the promising next-gen energy storage solutions owing to its ultrahigh energy density but suffers from problems such as high charging overpotential, slow redox kinetics and Li anode corrosion etc., calling for a systemic optimization of the battery configuration and structural components. Herein, an ingenious "trinity" design of LOB is initiated by implementing a hollowed cobalt metal organic framework (MOF) impregnating iodized polypyrrole simultaneously as the cathode catalyst, anode protection layer and slow-release capsule of redox mediators, so as to systemically address issues of impeded mass transport and redox kinetics on the cathode, dendrite growth and surface corrosion on the anode, as well as limited intermediate solubility in the low donor-number (DN) solvent. As a result of the systemic effort, the LOB constructed demonstrates an ultralow discharge/charge polarization of 0.2V, prolonged cycle life of 1200h and total discharge capacity of 28.41 mAh cm-2 . Mechanistic investigations attribute the superb LOB performance to the redox-mediated solution growth mechanism of crystalline Li2 O2 with both enhanced reaction kinetics and reversibility. This study offers a paradigm in designing smart materials to raise the performance bar of Li-O2 battery towards realistic applications. This article is protected by copyright. All rights reserved.

Binder-Free Cnt Cathodes for Li-O2 Batteries with More Than One Life.

Li-O2 batteries (LOB) performance degradation ultimately occurs through the accumulation of discharge products and irreversible clogging of the porous electrode during the cycling. Electrode binder degradation in the presence of reduced oxygen species can result in additional coating of the conductive surface, exacerbating capacity fading. Herein, a facile method to fabricate free-standing is established, binder-free electrodes for LOBs in which multi-wall carbon nanotubes form cross-linked networks exhibiting high porosity, conductivity, and flexibility. These electrodes demonstrate high reproducibility upon cycling in LOBs. After cell death, efficient and inexpensive methods to wash away the accumulated discharge products are demonstrated, as reconditioning method. The second life usage of these electrodes is validated, without noticeable loss of performance. These findings aim to assist in the development of greener high energy density batteries while reducing manufacturing and recycling costs.

Effects of Operating Temperature on Li-O2 Battery with Ionic Liquid-Based Binary Electrolyte

The progress of rechargeable Li-O2 battery (LOB) is hampered due to the number of challenges its components present. Among various critical challenges, the choice of electrolyte has always been a bottleneck impeding the breakthrough in the development of LOB. Various electrolytes, including organic solvents and room-temperature ionic liquids (RTILs) have been developed and studied. Each electrolyte comes with various limitations, which restrict its application in the LOB. These include thermal and electrochemical stability, volatility, viscosity, flammability, capability to dissolve incoming oxygen, diffusivity, and ionic conductivity. Consequently, no electrolyte could be regarded as an ideal electrolyte. Nonetheless, efforts have been made to tune the physiochemical properties of the electrolyte by blending two or more miscible solvents. High thermal and electrochemical stability and negligible volatility of RTILs can be combined with high diffusivity and ionic conductivity of organic solvents by merely blending them with optimized volume ratios.In this study, we comprehensively investigated the effects of operating temperature (20°C, 40°C and 60°C) on the electrochemical performance of LOBs incorporated with RTIL and organic solvent binary electrolyte. We designed and investigated, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2C1im][Tf2N]) RTIL and dimethyl sulfoxide (DMSO) organic solvent at various volume ratios ((4:1), (1:1), (1:4)). Among the binary electrolytes, ([C2C1im][Tf2N]/DMSO (1:4)) delivered the highest discharge capacities of 3.70 Ah g-1 (20°C), 4.0 Ah g-1 (40°C) and 3.65 Ah g-1 (60°C) as compared with pure [C2C1im][Tf2N] and DMSO. Cycling stability tests showed superior stability of the binary electrolyte ([C2C1im][Tf2N]/DMSO (1:4)) irrespective of the operating temperature. From viscosity and ionic conductivity measurements (at 20-60°C), [C2C1im][Tf2N]/DMSO (1:4) exhibited the highest ionic conductivity and the lowest viscosity compared with other binary electrolytes and pure RTIL at any given temperature. Cyclic voltammetry (CV) tests revealed a higher reaction rate with [C2C1im][Tf2N]/DMSO (1:4) binary electrolytes than pure electrolytes. The superior performance of [C2C1im][Tf2N]/DMSO (1:4) binary electrolyte was ascribed to enhanced stability against reactive intermediate species during oxygen reduction reaction (ORR), increased ionic conductivity, low viscosity (comparable with organic electrolytes), improved oxygen solubility, and relatively low evaporation rates. The detailed results and discussion will be presented during the presentation.

Quasi-solid-state composite polymer electrolyte with NASICON-type nanofillers for high performance lithium-oxygen batteries

This study designs a quasi-solid-state composite polymer electrolyte (QSCPE) to improve the performance of LiO2 batteries by integrating a composite solid framework and liquid electrolyte. The solid framework, containing poly(vinylidene difluoride-co-hexafluoropropylene) (PVDF-HFP) and sodium superionic conductor (NASICON)-type lithium aluminum germanium phosphate (LAGP) filler, is prepared using a conventional solution casting method. The framework is then activated using a liquid electrolyte to fabricate the QSCPE. The optimized electrolyte exhibits a high ionic conductivity and wide electrochemical stability. The Li/QSCPE/Li symmetric cell shows an overpotential of below 100 mV and a cycle life of >250 cycles at 1 mA cm−2 at a capacity of 2 mA h cm−2, ensuring electrochemical stability. The LiO2 cell fabricated using the optimized electrolyte exhibits significantly improved cyclability with a cycle life of 152. The QSCPE effectively prevents contamination of Li and suppresses the growth of Li dendrites. These results suggest that the LAGP nanofillers-containing QSCPE is a promising approach for further improving the performance of LiO2 batteries.

The Role of Self-Catalysis Induced by Co Doping in Nonaqueous Li-O2 Batteries.

This work systematically studies the product self-catalysis of in situ electrochemical cobalt doping of Li2O2 and reveals its potential mechanism for improving the performance of lithium-oxygen (Li-O2) batteries. Theoretical calculations demonstrate that the discharge products contain substituted and interstitial Co impurities, which serve as active sites to promote the formation of Li3O4 crystallization, thus switching the nucleation mechanism from the main discharge product Li2O2 to Li3O4. This Co-doping behavior leads to the thermodynamically favorable and dynamically stable formation of Li3O4 crystals during the discharge process. Through systematic investigation of the structural, energetic, electronic, diffusive, and catalytic properties of the Co-doped Li2O2 and Li3O4 compounds, we found that Li3O4 has better charge/mass transport and a lower overpotential for the Li3O4 formation/decomposition reaction. Consequently, this work elucidates that Co doping provides a simple and effective approach for increasing the proportion of Li3O4, which can significantly improve the Li-O2 battery performance.

Tuning solid electrolyte interface against oxygen/superoxide-derived attack on Li-metal anode in Li-O2 battery

Practical working environment (O2-saturated base electrolyte), architecture and operation mechanism/processes of Li-O2 batteries (LOBs) endows severe O2 and superoxide (O2-)-derived attack on Li-metal and solid electrolyte interface (SEI) at Li/electrolyte interface, limiting stability of Li anodes and LOBs. Herein, how O2/O2--derived attack on Li-metal and structure/composition of SEI are revealed by cryogenic transmission electron microscopy (cryo-TEM) and comprehensive spectroscopic characterizations. Specifically, generated from O2-reduction on Li-anode, the Li2O-induced nucleophilic attack on base electrolyte decomposition and Li corrosion especially during long-term aging, and more aggressive O2- created in cycling aggravates Li anodes and SEI. Moreover, to address O2/O2--derived attack on Li-metal, 1, 2-difluorobenzene (F-ben) was introduced as cosolvent in base electrolyte to make an F-ben electrolyte, in which F-ben preferentially reacted with Li-metal to form dual-functional SEI. Tuned SEI not only separate Li2O from bulk electrolyte thus suppresses O2-derived chemical attack, also acts as protective film protecting Li-metal against O2- attack. Eventually, electro-stability/reversibility of Li-metal in practical working environment of LOBs and battery performance of LOBs are significantly enhanced with help of F-ben cosolvent. This work sheds light on behavior of O2/O2--derived attack on Li-metal and SEI, sets an effective and practicable path towards practical applications of LOBs.