RESUMEN
Black phosphorus (BP) is a promising anode material in lithium-ion batteries (LIBs) owing to its high electrical conductivity and capacity. However, the huge volume change of BP during cycling induces rapid capacity fading. In addition, the unclear electrochemical mechanism of BP hinders the development of rational designs and preparation of high-performance BP-based anodes. Here, a high-performance nanostructured BP-graphite-carbon nanotubes composite (BP/G/CNTs) synthesized using ball-milling method is reported. The BP/G/CNTs anode delivers a high initial capacity of 1375 mA h g-1 at 0.15 A g-1 and maintains 1031.7 mA h g-1 after 450 cycles. Excellent high-rate performance is demonstrated with a capacity of 508.1 mA h g-1 after 3000 cycles at 2 A g-1 . Moreover, for the first time, direct evidence is provided experimentally to present the electrochemical mechanism of BP anodes with three-step lithiation and delithiation using ex situ X-ray diffraction (XRD), ex situ X-ray absorption spectroscopy (XAS), ex situ X-ray emission spectroscopy, operando XRD, and operando XAS, which reveal the formation of Li3 P7 , LiP, and Li3 P. Furthermore, the study indicates an open-circuit relaxation effect of the electrode with ex situ and operando XAS analyses.
RESUMEN
Aluminum foil is the predominant cathodic current collector in lithium-based batteries due to the high electronic conductivity, stable chemical/electrochemical properties, low density, and low cost. However, with the development of next-generation lithium batteries, Al current collectors face new challenges, such as the requirement of increased chemical stability at high voltage, long-cycle-life batteries with different electrolyte systems, as well as improved electronic conductivity and adhesion for new electrode materials. In this study, we demonstrate a novel graphene-like carbon (GLC) coating on the Al foil in lithium-based batteries. Various physical and electrochemical characterizations are conducted to reveal the electronic conductivity and electrochemical stability of the GLC-Al foil in both carbonate- and ether-based electrolytes. Full-cell tests, including Li-S batteries and high-voltage Li-ion batteries, are performed to demonstrate the significantly improved cycling and rate performance of batteries with the use of the GLC-Al foil as current collectors. The cell using the GLC-Al foil can greatly reduce the potential polarization in Li-S batteries and can obtain a reversible capacity of 750 mAh g-1 over 100 cycles at 0.5C. Even with high-sulfur-loading cathodes, the Li-S battery at 1C still maintains over 500 mAh g-1 after 100 cycles. In high-voltage Li-ion batteries, the GLC-Al foil significantly improves the high-rate performance, showing an increased retained capacity by over 100 mAh g-1 after 450 cycles at 1C compared to the bare foil. It is believed that the developed GLC-Al foil brings new opportunities to enhance the battery life of lithium-based batteries.