Decimal Solvent-Based High-Entropy Electrolyte Enabling the Extended Survival Temperature of Lithium-Ion Batteries to−130°C

Freezing and crystallization of commercial ethylene carbonate-based binary electrolytes,leading to irreversible damage to lithium-ion batteries(LIBs),remain a significant challenge for the survival of energy storage devices at extremely low temperatures(<−40°C).Herein,a decimal solvent-based high-entropy electrolyte is developed with an unprecedented low freezing point of−130°C to significantly extend the service temperature range of LIBs,far superior to−30°C of the commercial counterpart.Distinguished from conventional electrolytes,this molecularly disordered solvent mixture greatly suppresses the freezing crystallization of electrolytes,providing good protection for LIBs from possible mechanical damage at extremely low temperatures.Benefiting from this,our high-entropy electrolyte exhibits extraordinarily high ionic conductivity of 0.62 mS·cm−1 at−60°C,several orders of magnitude higher than the frozen commercial electrolytes.Impressively,LIBs utilizing decimal electrolytes can be charged and discharged even at an ultra-low temperature of−60°C,maintaining high capacity retention(∼80%at−40°C)as well as remarkable rate capability.This study provides design strategies of low-temperature electrolytes to extend the service temperature range of LIBs,creating a new avenue for improving the survival and operation of various energy storage systems under extreme environmental conditions.

Synthesis of dispersed long single-crystalline TiO_2 paste and its application in DSSC as a scattering layer

Ti O2 nanowire(NW) is one of the potential scattering layer materials in dye-sensitized solar cells(DSSCs) owing to its fast electron conductivity and excellent light scattering property resulting from its one-dimensional(1D) morphology. However, Ti O2 NWs used as scattering layers in previous work were either aggregated or shortened into shuttles that cannot use their unique 1D properties. In this paper, we present the preparation of a well-dispersed long NW paste(exceeding 1 ?m) by a mild method and used as a scattering layer in DSSC. The paste achieved a photoconversion efficiency of 5.73% and an efficiency enhancement of 12% compared with commercial scattering layer(P200 paste). Compared with the DSSC without a scattering layer, an efficiency enhancement of 54.9% was achieved. Also, the largest efficiency of 6.89% was obtained after optimization of photoanode thickness. The photoanodes were investigated through dye desorbed experiments and transmission spectra, which suggested that P25 nanoparticles with the as-prepared NW scattering layer loaded more dye than those with P200 paste. These results indicate that well-dispersed long NW paste has a potential application in scattering layers.