RESUMEN
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, 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 0.2 V, prolonged cycle life of 1244 h 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 toward realistic applications.
RESUMEN
As the promising next-generation energy storage solution, lithium metal battery (LMB) has gained great attention but still suffers from troubles associated with the highly active metallic lithium. Herein, it is aimed to develop an anode-free LMB engaging no Li disk or foil by modifying the Cu current collector with mercapto metal-organic frameworks (MOFs) impregnating Ag nanoparticles (NPs). While the polar mercapto groups facilitate and guide Li+ transport, the highly lithiophilic Ag NPs help to enhance the electric conductivity and lower the energy barrier of Li nucleation. Furthermore, the MOF pores allow compartmentalizing bulk Li into a 3D matrix Li storage so that not only the local current density is reduced, but also is the plating/stripping reversibility greatly enhanced. As a result, full cells pairing the prelithiated Ag@Zr-DMBD/Cu anodes with LiFePO4 cathodes demonstrate a high initial specific capacity of 159.8 mAh g-1 , first-cycle Coulombic efficiency of 96.6%, and long-term cycling stability over 1000 cycles with 99.3% capacity retention at 1 C. This study underlines the multi-aspect functionalization of MOFs to impart lithiophilicity, polarity, and porosity to achieve reversible Li plating/stripping and paves the way for realizing high-performance anode-free LMBs through exquisite modification of the Cu current collector.
RESUMEN
Owing to their structural tunability for furnishing high catalytic activity and photoactivity, perovskite oxides are a class of promising materials for high-performance photocathode catalysts in a photoassisted lithium oxygen battery (LOB), which is still in its infancy. Herein, single-crystalline LaCoO3 (LCO) is successfully synthesized through a microwave-assisted approach and selenylated to simultaneously introduce anionic doping and oxygen vacancies, boosting not only the electrocatalytic activity toward reversible Li2O2 formation/decomposition, but also the photoactivity to further reduce the charge/discharge polarization. As a result, LOBs utilizing Se-doped LCO as the photocathode catalyst demonstrate a superior performance under illumination in all aspects of energy efficiency, specific capacity, and cycling stability, ranking among the best reported in the literature for perovskite oxides. The photoenhanced charge kinetics is found to be correlated with the accelerated Li2O2 nucleation with lowered granule size, which is key to both the improved charge/discharge capacity and reversibility. The results underscore the tailoring of perovskite structure to aggrandize both the catalytic activity and photoactivity for concertedly promoting the kinetics of LOBs.
