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Constructing stable electrode/electrolyte interphase with fast interfacial kinetics is vital for fast‐charging batteries. Herein, we investigate the interphase that forms between a high‐voltage Na3V2(PO4)2F3 cathode and the electrolytes consisting of 3.0, 1.0, or 0.3 M NaClO4 in an organic carbonate solvent (47.5 : 47.5 : 5 mixture of EC: PC: FEC) during charging up to 4.5 V at 55 °C. It is found that a higher anion/solvent ratio in electrolyte solvation structure induces anion‐dominated interphase containing more inorganic species and more anion derivatives (CxClOy), which leads to a larger interfacial Na+ transport resistance and more unfavorable gas evolution. In comparison, a low anion/solvent ratio derives stable anion‐tuned interphase that enables better interfacial kinetics and cycle ability. Importantly, the performance of a failed cathode is restored by triggering the decomposition of CxClOy species. This work elucidates the role of tuning interphase in fast‐charging batteries. [ABSTRACT FROM AUTHOR]

Spinel LiNi0.5Mn1.5O4 (LNMO), high‐voltage and high‐power density, is a very promising cathode candidate. Nevertheless, its lack of cycling stability has historically been long accepted as an inherent issue. Based on the above problem, a strategy is initiated to directly address Mn dissolution and unstable interface structure. A beneficial solid‐phase reaction occurs at the LNMO interface, transforming the spinel phase into two functional phases. One is the layered phase that provides electrochemical activity and supports charge transport. The other is the rock‐salt like phase induced by Li/Mn exchange that can inhibit the dissolution of Mn and provide inert protection. The Li/Mn exchange structure increases the diffusion energy barriers of Mn, which restrains the loss of Mn, proven by the bond valence sum calculation. The two phases are modulated successfully at the LNMO interface to balance the stable material structure and excellent charge transfer, obtaining a sample with excellent electrochemical performance. The capacity retention rate of modified LNMO is 15% higher than that of the pristine sample after 500 cycles. The preparation method does not utilize any dopants or coatings and can play a guiding role in addressing issues regarding structural stability and electrochemical performance for cathode materials. [ABSTRACT FROM AUTHOR]

Achieving fast‐charging capabilities in Li‐ion batteries (LIBs)—charging 80% of the battery capacity within 15 minutes—while maintaining an acceptable cycle life remains challenging due to various polarizations occurring at elevated charge rates. Such a goal is more tough at subzero, as temperature reduction slows the kinetics process including electrolyte mass transport and electrode charge transfer, substantially increasing the risk of lithium plating. Herein, it is found that adding LiFSI to a LiPF6 carbonate‐based electrolyte alters the Li+ solvation structure, endowing the dual‐salt electrolyte with a higher Li+ diffusion coefficient and lower desolvation energy. Benefit from the smaller structural change and the formation of a robust, conductive solid electrolyte interphase, the 12Ah‐pouch cells based on LiNi0.52Co0.2Mn0.28O2 cathodes and graphite anodes demonstrate fast‐charging capabilities and stable cycling performance across a wide temperature range of −20 to 50 ℃: charging 89% and 93% of pouch cell capacity within 4 minutes at 25 and 50 ℃ and 82% within 15 minutes at −20 ℃, maintaining capacity retention of 94% after 2000 cycles at 8C at 0 ℃ and 89% after 350 cycles at −20 ℃ at 4C. This work might offer new insights into enhancing the fast‐charging capabilities of LIBs under extreme conditions. [ABSTRACT FROM AUTHOR]

It is challenging for flexible solid-state hybrid capacitors to achieve high-energy-high-power densities in both Li-ion and Na-ion systems, and the kinetics discrepancy between the sluggish faradaic anode and the rapid capacitive cathode is the most critical issue needs to be addressed. To improve Li-ion/Na-ion diffusion kinetics, flexible oxygen-deficient TiO 2- x /CNT composite film with ultrafast electron/ion transport network is constructed as self-supported and light-weight anode for a quasi-solid-state hybrid capacitor. It is found that the designed porous yolk-shell structure endows large surface area and provides short diffusion length, the oxygen-deficient composite film can improve electrical conductivity, and enhance ion diffusion kinetic by introducing intercalation pseudocapacitance, therefore resulting in advance electrochemical properties. It exhibits high capacity, excellent rate performance, and long cycle life when utilized as self-supported anodes for Li-ion and Na-ion batteries. When assembled with activated carbon/carbon nanotube (AC/CNT) flexible cathode, using ion conducting gel polymer as the electrolyte, high energy densities of 104 and 109 Wh kg -1 are achieved at 250 W kg -1 in quasi-solid-state Li-ion and Na-ion capacitors (LICs and SICs), respectively. Still, energy densities of 32 and 36 Wh kg -1 can be maintained at high power densities of 5000 W kg -1 in LICs and SICs., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)