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Rechargeable calcium batteries have attracted increasing attention as promising multivalent ion battery systems due to the high abundance of calcium. However, the development has been hampered by the lack of suitable cathodes to accommodate the large and divalent Ca2+ ions at a high redox potential with sufficiently fast ionic conduction. Herein, we report a new intercalation host which presents 500 cycles with a capacity retention of 90% and a remarkable power capability at ~3.2 V (vs. Ca/Ca2+) in a calcium battery. The cathode material derived from Na0.5VPO4.8F0.7 is demonstrated to reversibly accommodate a large amount of Ca2+ ions, forming a series of CaxNa0.5VPO4.8F0.7 (0, Rechargeable calcium batteries are promising multivalent battery systems but the lack of suitable electrodes hampers their development. Here the authors report a cathode derived from polyanion framework that demonstrates uncommonly stable and fast intercalation behaviours of calcium ions.

Magnesium (Mg) rechargeable batteries are one of the promising high-energy post-lithium battery chemistries exploiting the multivalent charge carrier. However, the use of magnesium metal has been c...

The all-solid-state battery (ASSB) has become one of the most promising next-generation battery systems, since the aspect of safety has emerged as a crucial criterion for new large-scale applications such as in electric vehicles. Despite the recent remarkable progress in the performance enhancement, the real-world implementation of the ASSB still requires full comprehension/evaluation of its properties and performance under various practical operational conditions. Unlike batteries employed in conventional electronic devices, those in electric vehicles—the major application that the ASSB is expected to be employed—would be exposed to wide temperature variations (−20 to ∼70 °C) at various states of charges due to their outdoor storage and irregular discharge/rest/charge conditions depending on vehicle drivers' usage patterns. Herein, we investigate the reliability of a Li6PS5Cl-based ASSB system in practically harsh but plausible storage conditions and reveal that it is vulnerable to elevated-temperature storage as low as 70 °C, which, in contrast to the common belief, causes significant degradation of the electrolyte and consequently irreversible buildup of the cell resistance. It is unraveled that this storage condition induces the decomposition of Li6PS5Cl in contact with the cathode material, involving the SOx gas evolution particularly at charged states, which creates a detrimental porous cathode/electrolyte interface, thereby leading to the large interfacial resistance. Our findings indicate that the stability of the solid electrolyte, which has been believed to be failsafe, needs to be carefully revisited at various practical operational conditions for actual applications in ASSBs.

The electrochemical properties and performances of lithium-ion batteries are primarily governed by their constituent electrode materials, whose intrinsic thermodynamic and kinetic properties are understood as the determining factor. As a part of complementing the intrinsic material properties, the strategy of nanosizing has been widely applied to electrodes to improve battery performance. It has been revealed that this not only improves the kinetics of the electrode materials but is also capable of regulating their thermodynamic properties, taking advantage of nanoscale phenomena regarding the changes in redox potential, solid-state solubility of the intercalation compounds, and reaction paths. In addition, the nanosizing of materials has recently enabled the discovery of new energy storage mechanisms, through which unexplored classes of electrodes could be introduced. Herein, we review the nanoscale phenomena discovered or exploited in lithium-ion battery chemistry thus far and discuss their potential implications, providing opportunities to further unveil uncharted electrode materials and chemistries. Finally, we discuss the limitations of the nanoscale phenomena presently employed in battery applications and suggest strategies to overcome these limitations.

Author(s): Xu, ZL; Park, J; Yoon, G; Kim, H; Kang, K | Abstract: Lithium-ion batteries (LIBs) have dominated the energy storage market for more than two decades; however, the quest for lower-cost battery alternatives is rapidly expanding, especially for large-scale applications. Sodium-ion batteries (SIBs) have recently experienced an impressive resurgence owing to the earth's abundance of sodium resources and the similar electrochemistry of SIBs and the well-established LIBs. Nonetheless, whereas cost-effective and reliable graphite anodes have served as a cornerstone in current LIB technology, one of the major limitations of SIBs has been the inability to exploit graphite as an electrode because of its negligible sodium storage capability. Recently, however, clear progress has been made in preparing high-performance graphitic carbon anodes for SIBs with new findings on the mechanisms of sodium storage. Herein, this paper aims to review the progress made in understanding the sodium storage mechanisms in graphitic carbon materials and comprehensively summarize the start-of-the-art achievements by surveying the correlations among the type of graphitic material, microstructure, sodium storage mechanisms, and electrochemical performance in SIBs. In addition, perspectives related to practical applications, including the electrolyte, coulombic efficiency, and applicability in sodium-ion full cells, are also presented.