Robust Benzimidazole-Based Electrolyte Overcomes High-Voltage and High-Temperature Applications in 5 V Class Lithium Ion Batteries

Electric vehicles (EVs) are poised to dominate the next generation of transportation, but meeting the power requirements of EVs with lithium ion batteries is challenging because electrolytes containing LiPF₆ and carbonates do not perform well at high temperatures and voltages. However, lithium benzimidazole salt is a promising electrolyte additive that can stabilize LiPF₆ through a Lewis acid–base reaction. The imidazole ring is not eligible for high-voltage applications owing to its resonance structure, but in this research, electron-withdrawing (−CF₃) and electron-donating (−CH₃) substitutions on imidazole rings were investigated. According to the calculation results, the CF₃ substitution facilitates a high electron cloud density on imidazole ring structures to resist the electron releases from bezimidazole in oxidation reactions. In addition, through CF₃ substitution, electrons are accepted from the lattice oxygen (O^2–) in lithium-rich layer material and O^– is converted by an electron released. The O^– is then adsorbed with the ethylene carbonate and catalyzed to alkyl carbonate by Ni²⁺. The −CF₃ substituted benzimidazole triggers a further reaction with alkyl carbonate and forms a new polyionic liquid solid electrolyte interphase on the cathode’s surface. Furthermore, the cycle performance tested at 60 °C and 4.8 V showed that the CF₃ substitution maintains the battery retention effectively and exhibits almost no fading compared with both the blank electrolyte and the CH₃ substitution

Performance Characterization of Dye-Sensitized Photovoltaics under Indoor Lighting

Indoor utilization of emerging photovoltaics is promising; however, efficiency characterization under room lighting is challenging. We report the first round-robin interlaboratory study of performance measurement for dye-sensitized photovoltaics (cells and mini-modules) and one silicon solar cell under a fluorescent dim light. Among 15 research groups, the relative deviation in power conversion efficiency (PCE) of the samples reaches an unprecedented 152%. On the basis of the comprehensive results, the gap between photometry and radiometry measurements and the response of devices to the dim illumination are identified as critical obstacles to the correct PCE. Therefore, we use an illuminometer as a prime standard with a spectroradiometer to quantify the intensity of indoor lighting and adopt the reverse-biased current–voltage (<i>I</i>–<i>V</i>) characteristics as an indicator to qualify the <i>I</i>–<i>V</i> sampling time for dye-sensitized photovoltaics. The recommendations can brighten the prospects of emerging photovoltaics for indoor applications