RESUMEN
With the increasing demand for high energy density and rapid charging performance, Li-rich materials have been the up and coming cathodes for next-generation lithium-ion batteries. However, because of oxygen evolution and structural instability, the commercialization of Li-rich materials is extremely retarded by their poor electrochemical performances. In this work, Li-deficient materials Li0.3NbO2 and (Nb0.62Li0.15)TiO3 are applied to functionalize the surface of Li1.2Mn0.54Ni0.13Co0.13O2, aiming to suppress oxygen evolution and increase structural stability in LIBs. In addition, a fast Li-ion transport channel is beneficial to enhance Li+ diffusion kinetics. The results demonstrate that the electrodes decorated with Li0.3NbO2 and (Nb0.62Li0.15)TiO3 materials exhibit more stable cycling stability after long-term cycling and outstanding rate capability.
RESUMEN
Improving the durability of cathode materials at low temperature is of great importance for the development nowadays of lithium ion batteries, since the practical capacity and cycling stability of the electrode are reduced significantly at low temperature. Herein, by amorphous Zr3(PO4)4 surface engineering, we realize a stable high-voltage LiCoO2 operation (4.6 V) at -25 °C. The highly amorphous surface layer can help to form a high-quality cathode-electrolyte interphase with strong stability and low interface resistance, especially at low temperature. Such a surface-engineered LiCoO2 shows a capacity of 179.2 mAh g-1 at 0.2C and an excellent cyclability with 91% capacity retention after 300 cycles (1C). As a comparison, bare LiCoO2 shows only 161.6 mAh g-1 and 1% capacity retention under the same circumstances. This work confirms that surface regulation and control engineering is an effective route to improve the high-voltage and low-temperature performance of LiCoO2.
RESUMEN
Carbonaceous materials featuring both ordered graphitic structure and disordered defects hold great promise for high-performance K-ion batteries (KIBs) due to the concurrent advantages of high electronic conductivity, fast and reversible K+ intercalation/deintercalation, and abundant active K+ storage sites. However, it has been a lingering problem and remains a big challenge because graphitization and defects are intrinsic trade-off properties of carbonaceous materials. Herein, for the first time, we propose a cobalt-catalyzed carbonization strategy to fabricate porous carbon nanofibers that incorporate disordered defects in graphitic domain layers (PCNFs-DG) for fast and durable K+ storage. The Co catalyst not only ensures the formation of highly graphitized carbon shells around the Co particles but also introduces nanopores and doping defects in the following catalyst removal process. This idea of architecting defected-ordered graphitic carbon engineering guarantees fast reaction kinetics as well as structural stability with negligible interlayer expansion/contraction owing to the uncompromised electronic conductivity, expanded interlayer spacing, and regulated K+ storage mechanism. These appealing features translate to a high reversible capacity of 318.5 mAh g-1 at 100 mA g-1 and ultrahigh stability with almost 100% capacity retention over 2000 cycles in KIBs. This work puts in perspective that defected and ordered carbonaceous materials could be simultaneously achieved, advancing their performance for next-generation energy storage systems.
RESUMEN
To improve the initial Coulombic efficiency, cycling stability, and rate performance of the Li-rich Mn-based Li1.2Mn0.54Ni0.13Co0.13O2 cathode, the combination of LiMn1.4Ni0.5Mo0.1O4 coating with Mo doping has been successfully carried out by the sol-gel method and subsequent dip-dry process. This strategy buffers the electrodes from the corrosion of electrolyte and enhances the lattice parameter, which could inhibit the oxygen release and maintain the structural stability, thus improving the cycle stability and rate capability. After LiMn1.4Ni0.5Mo0.1O4 modification, the initial discharge capacity reaches 272.4 mAh g-1 with a corresponding initial Coulombic efficiency (ICE) of 84.2% at 0.1C (1C = 250 mAh g-1), far higher than those (221.5 mAh g-1 and 68.9%) of the pristine sample. Besides, the capacity retention of the coated sample is enhanced by up to 66.8% after 200 cycles at 0.1C. Especially, the rate capability of the coated sample is 95.2 mAh g-1 at 5C. XRD, SEM, TEM, XPS, and Raman spectroscopy are adopted to characterize the morphologies and structures of the samples. This coating strategy has been demonstrated to be an effective approach to construct high-performance energy storage devices.
RESUMEN
The Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode has attracted great interest owing to its low cost, high capacity, and energy density. Nevertheless, rapid capacity fading is a critical problem because of direct contact of NCM811 with electrolytes and hence restrains its wide applications. To prevent the direct contact, the surface inert layer coating becomes a feasible strategy to tackle this problem. However, to achieve a homogeneous surface coating is very challenging. Considering the bonding effect between NCM811, polyvinylpyrrolidone (PVP), and polyaniline (PANI), in this work, we use PVP as an inductive agent to controllably coat a uniform conductive PANI layer on NCM811 (NCM811@PANI-PVP). The coated PANI layer not only serves as a rapid channel for electron conduction, but also prohibits direct contact of the electrode with the electrolyte to effectively hinder side reaction. NCM811@PANI-PVP thus exhibits excellent cyclability (88.7% after 100 cycles at 200 mA g-1) and great rate performance (152 mA h g-1 at 1000 mA g-1). In situ X-ray diffraction and in situ Raman are performed to investigate the charge-discharge mechanism and the cyclability of NCM811@PANI-PVP upon electrochemical reaction. This surfactant-modulated surface uniform coating strategy offers a new modification approach to stabilize Ni-rich cathode materials for lithium-ion batteries.
RESUMEN
A 3D hierarchical meso- and macroporous Na3V2(PO4)3-based hybrid cathode with connected Na ion/electron pathways is developed for ultra-fast charge and discharge sodium-ion batteries. It delivers an excellent rate capability (e.g., 86 mA h g(-1) at 100 C) and outstanding cycling stability (e.g., 64% retention after 10,000 cycles at 100 C), indicating its superiority in practical applications.