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Conversion-alloying-type compounds offer many new possibilities as anode materials for Li-ion cells, but also show some drawbacks related to their intrinsic characteristics. To overcome those limitations, the consecutive steps of electrochemical processes occurring in the selected Zn2SnO4 inverse spinel are studied in detail i.e. by operando X-ray diffraction, ex situ X-ray absorption spectroscopy, and transmission electron microscopy. Decomposition of the spinel phase upon the 1st lithiation proceeds with the precipitation of Li2O and metallic particles, which further form LiZn and LixSn. A multicomponent matrix is created, which allows for reversible lithium storage. After dealloying upon the 1st delithiation, a Li6ZnO4/Li4ZnO3-type phase is formed in the conversion reaction, indicating reactivity between ZnO and Li2O. Initially, α-Sn is likely precipitated, which is transformed into β-Sn during the 2nd cycle, indicating aggregation. Understanding the electrochemical reaction mechanism allowed identifying essential issues, important for the practical application of the Zn2SnO4 anode: too high reaction voltage vs. Li+/Li with large hysteresis during the conversion reaction; metallic particle aggregation; large volume changes during deep (de-)alloying; mechanical problems on prolonged cycling. While the full-range capacity of the developed anodes reaches 920 mA h g−1 after 10 cycles at a current of 50 mA g−1 and over 460 mA h g−1 at 1000 mA g−1, their operation range has to be limited in order to overcome the listed problems. This can be achieved by the controlled electrochemical prelithiation of Zn2SnO4 anodes before assembling full-cells. For the first time, excellent cycling stability is reached for micrometer-sized solid-state-synthesized Zn2SnO4, working in full Li-ion cells. [ABSTRACT FROM AUTHOR]

In this work, tiny CoFe2O4 nanoparticles with a diameter of several nanometers were firmly grown on carbon nanotube (CNT) through a solvothermal process followed with calcination step. The composite shows a coralline structure, where CoFe2O4 nanoparticles are dispersed finely on the surface of CNT. The coralline CoFe2O4-CNT composite electrode can deliver initial discharge/charge capacities of 1183.6/876.1 mAh g−1 at 100 mA g−1, with a Coulombic efficiency reaching up to 74.0%. The capacity drops first but ascends latter when the electrode is cycled 220 times at 200 mA g−1, giving a value of 747.5 mAh g−1 at 220th discharge process. Besides, the composite displays a capacity of 620.8 mAh g−1 even at a high rate of 1600 mA g−1, larger than commercialized graphite (372 mAh g−1). Thus, coralline CoFe2O4-CNT composite of remarkable electrochemical properties makes it a promising anode for lithium ion batteries. [ABSTRACT FROM AUTHOR]

A series of high performance carbonaceous mesoporous materials: activated carbon beads (ACBs), have been prepared in this work. Among the samples, ACB-5 possesses the BET specific surface area of 3537 m2 g−1 and ACB-2 has the pore volume of 3.18 cm3 g−1. Experimental measurements were carried out on the intelligent gravimetric analyzer (IGA-003, Hiden). Carbon dioxide adsorption capacity of 909 mg g−1 has been achieved in ACB-5 at 298 K and 18 bar, which is superior to the existing carbonaceous porous materials and comparable to metal-organic framework (MOF)-177 (1232 mg g−1, at 298 K and 20 bar) and covalent-organic framework (COF)-102 (1050 mg g−1 at 298 K and 20 bar) reported in the literature. Moreover, methane uptake reaches 15.23 wt % in ACB-5 at 298 K and 18 bar, which is better than MOF-5. To predict the performances of the samples ACB-2 and ACB-5 at high pressures, modeling of the samples and grand canonical Monte Carlo simulation have been conducted, as is presented in our previous work. The adsorption isotherms of CO2/N2 and CO2/CH4 in our samples ACB-2 and 5 have been measured at 298 and 348 K and different compositions, corresponding to the pre- and postcombustion conditions for CO2 capture. The Dual-Site Langmuir-Freundlich (DSLF) model-based ideal-adsorbed solution theory (IAST) was also used to solve the selectivity of CO2 over N2 and CH4. The selectivities of ACBs for CO2/CH4 are in the range of 2-2.5, while they remain in the range of 6.0-8.0 for CO2/N2 at T = 298 K. In summary, this work presents a new type of adsorbent-ACBs, which are not only good candidates for CO2 and CH4 storage but also for the capture of carbon dioxide in pre- and postcombustion processes. © 2011 American Institute of Chemical Engineers AIChE J, 2011 [ABSTRACT FROM AUTHOR]

The liquid-phase mass transport is the key factor affecting battery stability. The influencing mechanism of liquid-phase mass transport in the separators is still not clear, the internal environment being a complex multi-field during the service life of lithium-ion batteries. The liquid-phase mass transport in the separators is related to the microstructure of the separator and the physicochemical properties of electrolytes. Here, in-situ local electrochemical impedance spectra were developed to investigate local inhomogeneities in the mass transfer process of lithium-ion batteries. The geometric microstructure of the separator significantly impacts the mass transfer process, with a reduction in porosity leading to increased overpotentials. A competitive relationship among porosity, tortuosity, and membrane thickness in the geometric parameters of the separator were established, resulting in a peak of polarization. The resistance of the liquid-phase mass transfer process is positively correlated with the viscosity of the electrolyte, hindering ion migration due to high viscosity. Polarization is closely related to the electrochemical performance, so a phase diagram of battery performance and inhomogeneous mass transfer was developed to guide the design of the battery. This study provides a foundation for the development of high stability lithium-ion batteries., (© 2024 Wiley-VCH GmbH.)

Benefits emerging from applying high-entropy ceramics in Li-ion technology are already well-documented in a growing number of papers. However, an intriguing question may be formulated: how can the multicomponent solid solution-type material ensure stable electrochemical performance? Utilizing an example of nonequimolar Sn-based Sn 0.8 (Co 0.2 Mg 0.2 Mn 0.2 Ni 0.2 Zn 0.2 ) 2.2 O 4 high-entropy spinel oxide, we provide a comprehensive model explaining the observed very good cyclability. The material exhibits a high specific capacity above 600 mAh g -1 under a specific current of 50 mA g -1 and excellent capacity retention near 100% after 500 cycles under 200 mA g -1 . The stability originates from the conversion-alloying reversible reactivity of the amorphous matrix, which forms during the first lithiation from the initial high-entropy structure, and preserves the high level of cation disorder at the atomic scale. In the altered Li-storage mechanism in relation to the simple oxides, the unwanted aggregated metallic grains are not exsolved from the anode and therefore do not form highly lithiated phases characterized by large volumetric changes. Also, the electrochemical activity of Mg from the oxide matrix can be clearly observed. Because the studied compound was prepared by a conventional solid-state route, implementation of the presented approach is facile and appears usable for any oxide anode material containing a high-entropy mixture of elements.

Being considered as one of the most potential cathode materials, Li 1.15 Ni 0.17 Co 0.11 Mn 0.57 O 2 draws plenty of attention towards its optimization on cycling and rate performance. The surface coating process provides a longer cycling life and better rate performance for the cathodes. A systematic investigation has been carried out on the nano-AlPO 4 coating layer for the Li 1.15 Ni 0.17 Co 0.11 Mn 0.57 O 2 cathode material through a facile in situ dispersion process. The 1% coated cathode material can hold about 90% capacity retention after 100 cycles. Besides, the surface coating enhances the rate ability of Li 1.15 Ni 0.17 Co 0.11 Mn 0.57 O 2 , which holds a reversible capacity of 202.3 mAh g -1 at the rate of 1C. Surface information is collected during cycling, which reveals that less side reactions occur on the electrode-electrolyte interface after the coating process for improved cycling and rate performance.