Electrolyte effects on electron transport and recombination at ZnO nanorods (nd-ZnO) were studied by electrochemical impedance spectroscopy (EIS) in dye-sensitized solar cells (DSSCs). Different electrolyte systems were prepared by gradually adding tert-butylpyridine (TBP) and guanidinium thiocyanate (GuSCN) and replacing LiI with 1-butyl-3-methylimidazolium iodide (BMII). The introduction of TBP and GuSCN, and the replacement of LiI with BMII suppressed charge recombination at the nd-ZnO/electrolyte interface, increased electron lifetime (τn), improved electron transport, and reduced collection time (τd) on nd-ZnO. In addition, they improved the electron diffusion coefficient (D n) and elongated the effective diffusion length (L n). The electron transfer coefficient (β) at the ZnO/electrolyte interface was increased from 0.34 to 0.44, which was a good sign of improvement in fill factor (FF). In addition, the ohmic series resistance was reduced from 17.35 to 4.99 Ω·cm2 and the charge transfer resistance was decreased from 18.49 to 7.09 Ω·cm2 at the electrolyte/Pt interface. Nd-ZnO DSSCs using different electrolytes were tested and the improvement of open circuit voltage (V oc), short circuit current density (J sc), fill factor (FF), and incident photon to electron conversion efficiency (IPCE) was in good agreement with the findings from the EIS data.

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High-energy-density Li-metal batteries are of great significance in the energy storage field. However, the safety hazards caused by Li dendrite growth and flammable organic electrolytes significantly hinder the widespread application of Li-metal batteries. In this work, we report a highly safe electrolyte composed of 4 M lithium bis­(fluorosulfonyl)­imide (LiFSI) dissolved in the single solvent trimethyl phosphate (TMP). By regulating the solvation structure of the electrolyte, a combination of nonflammability and Li dendrite growth suppression was successfully realized. Both Raman spectroscopy and molecular dynamics simulations revealed improved dendrite-free Li anode originating from the unique solvation structure of the electrolyte. Symmetric Li/Li cells fabricated using this nonflammable electrolyte had a long cycle life of up to 1000 h at a current density of 0.5 mA cm–2. Furthermore, the Li4Ti5O12/TMP-4/Li full cells also exhibited excellent cycling performance with a high initial discharge capacity of 170.5 mAh g–1 and a capacity retention of 92.7% after 200 cycles at 0.2 C. This work provides an effective approach for the design of safe electrolytes with favorable solvation structure toward the large-scale application of Li-metal batteries.