ABSTRACT
The effects of lithium bis(fluorosulfonyl)imide, Li[N(SO2F)2] (LiFSI), as an additive on the low-temperature performance of graphiteâLiCoO2 pouch cells are investigated. The cell, which includes 0.2M LiFSI salt additive in the 1M lithium hexafluorophosphate (LiPF6)-based conventional electrolyte, outperforms the one without additive under -20 °C and high charge cutoff voltage of 4.3 V, delivering higher discharge capacity and promoted rate performance and cycling stability with the reduced change in interfacial resistance. Surface analysis results on the cycled LiCoO2 cathodes and cycled graphite anodes extracted from the cells provide evidence that a LiFSI-induced improvement of high-voltage cycling stability at low temperature originates from the formation of a less resistive solid electrolyte interphase layer, which contains plenty of LiFSI-derived organic compounds mixed with inorganics that passivate and protect the surface of the cathode and anode from further electrolyte decomposition and promotes Li+ ion-transport kinetics despite the low temperature, inhibiting Li metal-plating at the anode. The results demonstrate the beneficial effects of the LiFSI additive on the performance of a lithium-ion battery for use in battery-powered electric vehicles and energy storage systems in cold climates and regions.
ABSTRACT
We report a promising approach to achieve the maximum capacity (>230 mA h g-1) and high capacity retention (95% during 100 cycles) of a nickel-rich cathode of LiNi0.8Co0.1Mn0.1O2 (NCM811) by charging to 4.5 V in a non-flammable electrolyte of propylene carbonate and fluorinated linear carbonates. Our electrolyte permits the stabilization of the cathode-electrolyte interface and cathode structure at high-voltage, enabling stable and safe operation of the Ni-rich cathode for high-energy density and high-safety lithium-ion and lithium metal batteries.
ABSTRACT
The objectives of this study were to summarize the curriculum, history, and clinical researches of Chuna in Korea and to ultimately introduce Chuna to Western medicine. Information about the history and insurance coverage of Chuna was collected from Chuna-related institutions and papers. Data on Chuna education in all 12 Korean medicine (KM) colleges in Korea were reconstructed based on previously published papers. All available randomized controlled trials (RCTs) of Chuna in clinical research were searched using seven Korean databases and six KM journals. As a result, during the modern Chuna era, one of the three periods of Chuna, which also include the traditional Chuna era and the suppressed Chuna era, Chuna developed considerably because of a solid Korean academic system, partial insurance coverage, and the establishment of a Chuna association in Korea. All of the KM colleges offered courses on Chuna-related subjects (CRSs); however, the total number of hours dedicated to lectures on CRSs was insufficient to master Chuna completely. Overall, 17 RCTs were reviewed. Of the 14 RCTs of Chuna in musculoskeletal diseases, six reported Chuna was more effective than a control condition, and another six RCTs proposed Chuna had the same effect as a control condition. One of these 14 RCTs made the comparison impossible because of unreported statistical difference; the last RCT reported Chuna was less effective than a control condition. In addition, three RCTs of Chuna in neurological diseases reported Chuna was superior to a control condition. In conclusion, Chuna was not included in the regular curriculum in KM colleges until the modern Chuna era; Chuna became more popular as the result of it being covered by Korean insurance carriers and after the establishment of a Chuna association. Meanwhile, the currently available evidence is insufficient to characterize the effectiveness of Chuna in musculoskeletal and neurological diseases.
