RESUMEN

The very high theoretical specific energy of the lithium-air (Li-O2) battery (3500 Wh kg-1) compared with other batteries makes it potentially attractive, especially for the electrification of flight. While progress has been made in realizing the Li-air battery, several challenges remain. One such challenge is achieving a high capacity to store charge at the positive electrode at practical current densities, without which Li-air batteries will not outperform lithium-ion. The capacity is limited by the mass transport of O2 throughout the porous carbon positive electrode. Here it is shown that by replacing the binder in the electrode by a polymer with the intrinsic ability to transport O2, it is possible to reach capacities as high as 31 mAh cm-2 at 1 mA cm-2 in a 300 µm thick electrode. This corresponds to a positive electrode energy density of 2650 Wh L-1 and specific energy of 1716 Wh kg-1, exceeding significantly Li-ion batteries and previously reported Li-O2 cells. Due to the enhanced oxygen diffusion imparted by the gas diffusion polymer, Li2O2 (the product of O2 reduction on discharge) fills a greater volume fraction of the electrode and is more homogeneously distributed.

RESUMEN

Redox mediators (RMs) are widely utilized in the electrolytes of Li-O2 batteries to catalyze the formation/decomposition of Li2O2, which significantly enhances the cycling performance and reduces the charge overpotential. However, RMs have a shuttle effect by migrating to the Li anode side and inducing Li metal degradation through a parasitic reaction. Herein, a metal-organic framework gel (MOF-gel) separator is proposed to restrain the shuttling of RMs. Compared to traditional MOF nanoparticles, MOF gels form uniform and dense films on the separators. When using Ru(acac)3 (ruthenium acetylacetonate) as an RM, the MOF-gel separator suppresses the shuttling of Ru(acac)3 toward the Li anode side and significantly enhances the performance of Li-O2 batteries. Specifically, Li-O2 batteries exhibit an ultralong cycling life (410 cycles) at a current density of 0.5 A g-1. Moreover, the batteries using the MOF-gel/celgard separator exhibit significantly improved cycling performance (increase by ≈1.6 times) at a high current density of 1.0 A g-1 and a decreased charge/discharge overpotential. This result is expected to guide future development of battery separators and the exploration of redox mediators.

RESUMEN

Lithium-oxygen batteries show promising energy storage potential with high theoretical energy density; however, further investigation of chemical reactions is required. In this study, experimental Raman and theoretical analyzes are performed for a Li-O2 battery with LiClO4/dimethyl sulfoxide (DMSO) electrolyte and carbon cathode to understand the role of intermediate species in the reactional mechanism of the cell using a high donor number solvent. Operando Raman results reveal reversible changes in the DMSO bands, in addition to the formation and decomposition of Li2O2. On discharge, a decrease in DMSO polarizability is observed and bands of DMSO-Li+-anion interactions are evidenced and supported by ab initio density functional theory (DFT) calculations. Molecular dynamics (MD) force field simulations and operando Raman show that DMSO interacts with LiO2(sol), highlighting the stability of the electrolyte compared to the interaction with reactive O 2 - ${\rm O}_2^{-}$ . On charging, the presence of Li+ indicates the formation of a lithium-deficient phase, followed by the release of Li+ and oxygen. Therefore, this study contributes to understanding the discharge/charge chemistry of a Li-O2 cell, employing a common carbon cathode and DMSO electrolyte. The combination of a simple characterization technique in operando mode and theoretical studies provides essential information on the mechanism of Li-O2 system.

RESUMEN

Limited triple-phase boundaries arising from the accumulation of solid discharge product(s) in solid-state cathodes (SSCs) pose a challenge to high-property solid-state lithium-oxygen batteries (SSLOBs). Light-assisted SSLOBs have been gradually explored as an ingenious system; however, the fundamental mechanisms of the SSCs interface behavior remain unclear. Here, we discovered that light assistance can enhance the fast inner-sphere charge transfer in SSCs and regulate the discharge products with spherical particles generated via the surface growth model. Moreover, the high photoelectron excitation and transportation capabilities of SSCs can retard cathodic catalytic decay by avoiding structural degradation of the cathode with a reduced charge voltage. The light-induced SSLOBs exhibited excellent stability (170 cycles) with a low discharge-charge polarization overpotential (0.27 V). Furthermore, transparent SSLOBs with exceptional flexibility, mechanical stability, and multiform shapes were fabricated for theory-to-practical applications in sunlight-induced batteries. Our study opens new opportunities for the introduction of solar energy into energy storage systems.

RESUMEN

Lithium-oxygen batteries (LOBs) with a theoretical energy density of up to 3500 Wh kg-1 hold a promise for the next-generation high-energy-density batteries. However, the slow oxygen reduction/evolution kinetics at the cathode limits the performance of Li-air batteries. The rational design of efficient catalysts is essential for the improvement of oxygen electrode reaction kinetics. Herein, we report a facile strategy to co-dope N and P atoms simultaneously into Ti3C2Tx (NP-Ti3C2Tx) MXene via an electrostatic self-assembly approach. The co-doped NP-Ti3C2Tx layers expose abundant active sites, providing more space for accommodating the formed Li2O2. Moreover, the N and P co-doping facilitates efficient electron transport in Ti3C2Tx MXene. The LOB with NP-Ti3C2TX catalyst delivers a high discharge capacity of 24,940 mAh/g at 1000 mA g-1. At a cut-off capacity of 1000 mAh/g, this battery runs continuously for 159, 276, 185, and 229 cycles at current densities of 1000, 2000, 3000, and 5000 mA g-1, respectively. Theoretical calculations unveil that N and P co-doping enables lower ηORR and ηOER of only 0.26 V and 0.13 V on Ti3C2Tx MXene, respectively. This work offers a feasible approach for constructing efficient MXene electrocatalysts for Li-air batteries.

RESUMEN

Lithium-oxygen batteries, with their very high energy density (3500 Wh kg-1), could represent a real breakthrough in the envisioned strategies towards more efficient energy storage solutions for a less and less carbonated energy mix. However, the problems associated with this technology are numerous. A first one is linked to the high reactivity of the lithium metal anode, while a second one is linked to the highly oxidative environment created by the cell's O2 saturation. Keeping in mind the necessity for greener materials in future energy storage solutions, in this work an innovative lithium protective membrane is prepared based on chitosan, a polysaccharide obtained from the deacetylation reaction of chitin. Chitosan was methacrylated through a simple, one-step reaction in water and then cross-linked by UV-induced radical polymerization. The obtained membranes were successively activated in liquid electrolyte and used as a lithium protection layer. The cells prepared with protected lithium were able to reach a higher full discharge capacity, and the chitosan's ability to slow down degradation processes was verified by post-mortem analyses. Moreover, in long cycling conditions, the protected lithium cell performed more than 40 cycles at 0.1 mA cm-2, at a fixed capacity of 0.5 mAh cm-2, retaining 100% coulombic efficiency, which is more than twice the lifespan of the bare lithium cell.

RESUMEN

For lithium-oxygen batteries (LOBs), the leakage and volatilization of a liquid electrolyte and its poor electrochemical performance are the main reasons for the slow industrial advancement. Searching for more stable electrolyte substrates and reducing the use of liquid solvents are crucial to the development of LOBs. In this work, a well-designed succinonitrile-based (SN) gel polymer electrolyte (GPE-SLFE) is prepared by in situ thermal cross-linking of an ethoxylate trimethylolpropane triacrylate (ETPTA) monomer. The continuous Li+ transfer channel, formed by the synergistic effect of an SN-based plastic crystal electrolyte and an ETPTA polymer network, endows the GPE-SLFE with a high room-temperature ionic conductivity (1.61 mS cm-1 at 25 °C), a high lithium-ion transference number (tLi+ = 0.489), and excellent long-term stability of the Li/GPE-SLFE/Li symmetric cell at a current density of 0.1 mA cm-2 for over 220 h. Furthermore, cells with the GPE-SLFE exhibit a high discharge specific capacity of 4629.7 mAh g-1 and achieve 40 cycles.

RESUMEN

Lithium-oxygen batteries (LOBs) are well known for their high energy density. However, their reversibility and rate performance are challenged due to the sluggish oxygen reduction/evolution reactions (ORR/OER) kinetics, serious side reactions and uncontrollable Li dendrite growth. The electrolyte plays a key role in transport of Li+ and reactive oxygen species in LOBs. Here, we tailored a dilute electrolyte by screening suitable crown ether additives to promote lithium salt dissociation and Li+ solvation through electrostatic interaction. The electrolyte containing 100 mM 18-crown-6 ether (100-18C6) exhibits enhanced electrochemical stability and triggers a solution-mediated Li2 O2 growth pathway in LOBs, showing high discharge capacity of 10 828.8 mAh gcarbon -1 . Moreover, optimized electrode/electrolyte interfaces promote ORR/OER kinetics on cathode and achieve dendrite-free Li anode, which enhances the cycle life. This work casts new lights on the design of low-cost dilute electrolytes for high performance LOBs.

RESUMEN

Solid-state lithium-metal batteries using inorganic solid-state electrolyte (SSE) instead of liquid-electrolyte, especially lithium-oxygen (Li-O2) battery, have attracted much more attention due to their high-energy density and safety. However, the poor interface contact between electrodes and SSEs makes these batteries lose most of their capacity and power during cycling. Here we report that by coating a heterogeneous silicon carbide on lithium metal anode and Li1.5Al0.5Ge1.5P3O12(LAGP)-SSE, a good interface contact is created between the electrode and electrolyte that can effectively reduce the interface impedance and improve the cycle performance of the assembled battery. As a result, the solid-sate Li-O2battery demonstrates a cycle lifespan of ∼78 cycles being at least 3-times higher than the solid-state Li-O2battery without silicon carbide with a capacity limitation of 1000 mAh g-1at 250 mA g-1. The characterization of discharge products indicates a typical two-electron convention of oxygen-to-lithium oxide for the solid-state Li-O2battery system. This work paves a way for developing high-energy long-cycle solid-state lithium-metal battery. The work provides insights into the interface between the Li-metal and SSE to develop high-energy long-cycle all solid-state Li-metal batteries.

RESUMEN

Co3O4-MoSe2@C nanocomposite has been prepared by a convenient method via combining hydrothermally synthesized MoSe2@C and Co3O4. When catalyzing the hydrogen evolution reaction and oxygen evolution reaction, the catalyst features low overpotentials of 144 mV and 360 mV (both at 10 mA cm-2current density), respectively. It can also serve as the cathode in the lithium-oxygen battery and the device shows a low charging-discharging overpotential of 1.50 V with a stable performance of over 200 cycles at current density of 1000 mA g-1, shedding light on the design and synthesis of novel multifunctional electrocatalysts for energy conversions.

RESUMEN

Lithium-oxygen batteries have received great research interest owing to their ultrahigh theoretical energy density and are considered as one of the promising secondary batteries. However, there are still some challenges in their practical application, like liquid organic electrolyte evaporation in the semi-open system and instability in the high-voltage oxidizing environment. In this work, a cellulose acetate-based gel polymer electrolyte (CA@GPE) is proposed, whose cross-linked microporous structure ensures the ultrahigh liquid electrolyte uptake of 2391%. The prepared CA@GPE exhibits a high lithium-ion transference number of 0.595, a satisfying ionic conductivity of 0.47 mS cm-1 and a wide electrochemical stability window up to 5.0 V. The Li//Li symmetric cell employing CA@GPE could cycle stably over 1200 h. The lithium-oxygen battery with CA@GPE presents a superb cycling lifetime of 370 cycles at 0.1 mA cm-2 under 0.25 mAh cm-2 . This work offers a possible strategy to realize long-cycling stability lithium-oxygen batteries.

RESUMEN

Electronic structural engineering plays a key role in the design of high-efficiency catalysts. Here, to achieve optimal electronic states, introduction of exotic Fe dopant and Co vacancy into CoSe2 nanosheet (denoted as Fe-CoSe2-VCo) is presented. The obtained Fe-CoSe2-VCo demonstrates excellent catalytic activity as compared to CoSe2. Experimental results and density functional theory (DFT) calculations confirm that Fe dopant and Co defects cause significant electron delocalization, which reduces the adsorption energy of LiO2 intermediate on the catalyst surface, thereby obviously improving the electrocatalytic activity of Fe-CoSe2-VCo towards oxygen redox reactions. Moreover, the synergistic effect between Co vacancy and Fe dopant is able to optimize the microscopic electronic structure of Co ion, further reducing the energy barrier of oxygen electrode reactions on Fe-CoSe2-VCo. And the lithium-oxygen batteries (LOBs) based on Fe-CoSe2-VCo electrodes demonstrate a high Coulombic efficiency (CE) of about 72.66%, a large discharge capacity of about 13723 mA h g-1, and an excellent cycling life of about 1338 h. In general, the electronic structure modulation strategy with the reasonable introduction of vacancy and dopant is expected to inspire the design of highly efficient catalysts for various electrochemical systems.

RESUMEN

Lithium metal anode is regarded as the ultimate negative electrode material due to its high theoretical capacity and low electrochemical potential. However, the significantly high reactivity of Li metal limits the practical application of Li metal batteries. To improve the stability of the interface between Li metal and an electrolyte, a facile and scalable blade coating method was used to cover the commercial polyethylene membrane separator with an inorganic/organic composite solid electrolyte layer containing lithium-ion-conducting ceramic fillers. The coated separator suppressed the interfacial resistance between the Li metal and the electrolyte and consequently prolonged the cycling stability of deposition/dissolution processes in Li/Li symmetric cells. Furthermore, the effect of the coating layer on the discharge/charge cycling performance of lithium-oxygen batteries was investigated.

RESUMEN

Although sufficient tolerance against attack by superoxide radicals (O2 - ) has been mainly recognized as an important property for Li-O2 battery (LOB) electrolytes, recent evidence has revealed that other critical factors also govern the cyclability, prompting a reconsideration of the basic design guidelines of LOB electrolytes. Here, we found that LOBs equipped with a N,N-dimethylacetamide (DMA)-based electrolyte exhibited better cyclability compared with other standard LOB electrolytes. This superior cyclability is attributable to the capabilities of quenching 1 O2 and forming highly decomposable Li2 O2 . The 1 O2 quenching capability is equivalent to that of a tetraglyme-based electrolyte containing a several millimolar concentration of a typical chemical quencher. Based on these overlooked factors, the DMA-based electrolyte led to superior cyclability despite its lower O2 - tolerance. Thus, the present work provides a novel design guideline for the development of LOB electrolytes.

RESUMEN

Lithium-oxygen (Li-O2 ) batteries possess the highest theoretical energy density (3500 Wh kg-1 ), which makes them attractive candidates for modern electronics and transportation applications. In this work, an inexpensive, flexible, and wearable Li-O2 battery based on the bifunctional redox mediator of InBr3 , MoS2 cathode catalyst, and Fomblin-based oxygen permeable membrane that enable long-cycle-life operation of the battery in pure oxygen, dry air, and ambient air is designed, fabricated, and tested. The battery operates in ambient air with an open system air-breathing architecture and exhibits excellent cycling up to 240 at the high current density of 1 A g-1 with a relative humidity of 75%. The electrochemical performance of the battery including deep-discharge capacity, and rate capability remains almost identical after 1000 cycle in a bending fatigue test. This finding opens a new direction for utilizing high performance Li-O2 batteries for applications in the field of flexible and wearable electronics.

Asunto(s)

RESUMEN

The increasing interest in lithium-oxygen batteries (LOB), having the highest theoretical energy densities among the advanced lithium batteries, has triggered the search for in-situ characterization techniques, including Electrochemical Atomic Force Microscopy (EC-AFM). In this work we addressed the characterization of the formation and decomposition of lithium peroxide (Li2O2) on a carbon cathode using a modified AFM technique, called Flow Electrochemical Atomic Force Microscopy (FE-AFM), where an oxygen-saturated solution of the non-aqueous lithium electrolyte is circulated through a liquid AFM cell. This novel technique does not require keeping the AFM equipment inside a glove-box, and it allows performing a number of experiments using the same substrate with different electrolytes without disassembling the cell. We study the morphology of Li2O2 on graphite carbon using lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) in dimethyl sulphoxide (DMSO) as electrolyte under different operational conditions, in order to compare our results with those reported using other electrolytes and in-situ and ex-situ EC-AFM.

RESUMEN

A rechargeable lithium-oxygen battery (LOB) operates via the electrochemical formation and decomposition of solid-state Li2O2 on the cathode. The rational design of the cathode nanoarchitectures is thus required to realize high-energy-density and long-cycling LOBs. Here, we propose a cathode nanoarchitecture for LOBs, which is composed of mesoporous carbon (MPC) integrated with carbon nanotubes (CNTs). The proposed design has the advantages of the two components. MPC provides sufficient active sites for the electrochemical reactions and free space for Li2O2 storage, while CNT forests serve as conductive pathways for electron and offer additional reaction sites. Results show that the synergistic architecture of MPC and CNTs leads to improvements in the capacity (~ 18,400 mAh g- 1), rate capability, and cyclability (~ 200 cycles) of the CNT-integrated MPC cathode in comparison with MPC.

RESUMEN

A high energy efficiency, low charging voltage cathode is of great significance for the development of non-aqueous lithium-oxygen batteries. Non-stoichiometric manganese dioxide (MnO2-x) and chromium trioxide (Cr2O3) are known to have good catalytic activities for the discharging and charging processes, respectively. In this work, we prepared a cathode based on Cr2O3 decorated MnO2-x nanosheets via a simple anodic electrodeposition-electrostatic adsorption-calcination process. This combined fabrication process allowed the simultaneous introduction of abundant oxygen vacancies and trivalent manganese into the MnO2-x nanosheets, with a uniform load of a small amount of Cr2O3 on the surface of the MnO2-x nanosheets. Therefore, the Cr2O3/MnO2-x electrode exhibited a high catalytic effect for both discharging and charging, while providing high energy efficiency and low charge voltage. Experimental results show that the as-prepared Cr2O3/MnO2-x cathode could provide a specific capacity of 6,779 mA·h·g-1 with a terminal charge voltage of 3.84 V, and energy efficiency of 78%, at a current density of 200 mA·g-1. The Cr2O3/MnO2-x electrode also showed good rate capability and cycle stability. All the results suggest that the as-prepared Cr2O3/MnO2-x nanosheet electrode has great prospects in non-aqueous lithium-oxygen batteries.

RESUMEN

The lithium (Li)-air battery has an ultrahigh theoretical specific energy, however, even in pure oxygen (O2 ), the vulnerability of conventional organic electrolytes and carbon cathodes towards reaction intermediates, especially O2 - , and corrosive oxidation and crack/pulverization of Li metal anode lead to poor cycling stability of the Li-air battery. Even worse, the water and/or CO2 in air bring parasitic reactions and safety issues. Therefore, applying such systems in open-air environment is challenging. Herein, contrary to previous assertions, we have found that CO2 can improve the stability of both anode and electrolyte, and a high-performance rechargeable Li-O2 /CO2 battery is developed. The CO2 not only facilitates the in situ formation of a passivated protective Li2 CO3 film on the Li anode, but also restrains side reactions involving electrolyte and cathode by capturing O2 - . Moreover, the Pd/CNT catalyst in the cathode can extend the battery lifespan by effectively tuning the product morphology and catalyzing the decomposition of Li2 CO3 . The Li-O2 /CO2 battery achieves a full discharge capacity of 6628 mAh g-1 and a long life of 715 cycles, which is even better than those of pure Li-O2 batteries.

RESUMEN

An exceptionally strong solvation effect of dimethyl sulfoxide (DMSO) on I2 is identified by the largest shift observed so far of the I2 Raman peak with respect to I2 vapor and by elongated I-I bond lengths in first-principles molecular-dynamics simulations. This effect together with strong binding by an RuO2 surface to I2 is found to invert the direction of the reaction I- +I2 ⇌I3 - to the left-hand side. Inspired by this finding, we prepared a Li-O2 battery with the Li/DMSO+LiI/RuO2 structure. The synergic action of DMSO and RuO2 on I2 is found to suppress the shuttle effect of the redox mediator (RM) by anchoring I2 molecules, the oxidation product of the RM. Significantly enhanced stability is demonstrated over 100 cycles at charging voltage below 3.65 V.