Abstract Formamidinium lead iodide (FAPbI3) perovskites are promising for high-performance solar cells; however, the low surface energy of self-assembled monolayers (SAMs) impedes α-phase nucleation in inverted devices. Here, we report a formamidinium (FA)-solvent intermediate-mediated self-seeding crystallization strategy to enable quality α-phase FAPbI3. By employing N-formylmorpholine (NFM) as a non-toxic solvent, (FA···NFM)PbI3 intermediates are formed, thereby lowering the phase-transition barrier and promoting the spontaneous formation of α-phase nuclei at the early stage of crystallization. These preformed nuclei serve as intrinsic seeds, facilitating rapid nucleation and orientated crystal growth. Consequently, NFM-based devices achieve efficiencies of 26.41% and 26.56% using 2-methoxyethanol (2-Me) and N,N-dimethylformamide (DMF) as primary solvents, respectively, with a 1 cm2 device reaching 25.47%. The unencapsulated devices retain 85% and 90% of their initial efficiencies after 1200 h illumination and 1400 h thermal aging at 85 °C, respectively.
Abstract Silicon anodes unlock higher energy density in Li-ion batteries but suffer from poor calendar life due to inadequately passivating solid–electrolyte interphases (SEIs). Here, we contrast the calendar aging behaviors of single- and mixed-salt locally superconcentrated electrolytes (LSCEs) against carbonate electrolytes. Mixed-salt LSCE cells retained 96% and 44% of precalendar capacity after one month and then after five months, while carbonate electrolyte cells retained 77% and 1%, respectively. The mixed-salt LSCE advantage is tied to the formation of a predominantly inorganic SEI, evidenced by nanoscale Fourier transform infrared spectromicroscopy, X-ray photoelectron spectroscopy, and 3D time-of-flight secondary ion mass spectrometry. After 5 months, however, perturbations to SEIs were evident in all cells, accelerating voltage decay and capacity loss by lithium inventory loss associated with SEI growth. These findings suggest that future electrolytes may benefit from strategies that continuously reinforce the SEI through controlled anion and solvent redox in LSCEs.
Abstract Lithium–sulfur (Li–S) batteries are severely hindered by the shuttle effect of lithium polysulfides (LiPSs) and uncontrolled lithium dendrite growth. Herein, a defect-engineered MOF-303 (D-MOF-303) modified separator is developed via a ball-milling strategy to simultaneously mitigate both issues, marking the first application of MOF-303 in the Li–S battery field. The intentional introduction of ligand defects and oxygen vacancies reduces particle size, establishes a hierarchical porous structure, and amplifies local Lewis acidity. Consequently, the D-MOF-303 coating layer provides exceptional chemisorption and accelerated electrocatalytic conversion kinetics for LiPSs, while concurrently homogenizing lithium-ion flux to achieve long-term dendrite-free lithium plating. Benefiting from these synergistic merits, the resulting Li–S full cells exhibit high capacity retention over 500 cycles at 0.5 C, enhanced rate capability up to 3 C, and notable environmental resilience under high-humidity aging conditions. This work demonstrates the potential of coordination defect engineering in metal–organic frameworks for advancing high-energy-density and commercially viable energy storage technologies.
Abstract Fluorinated ether electrolytes are promising for high-energy-density lithium metal batteries, yet their translation to larger-scale production requires systematic control of solvent impurities generated during synthesis and purification. Using 2-(2-(2,2-difluoroethoxy)ethoxy)–1,1,1-trifluoroethane (F5DEE) as a high-performance model solvent, we compare gram- and kilogram-scale batches to correlate impurity origin, purification, and electrochemistry. Although upscaled F5DEE shows >99% purity by standard techniques, ppm-level moisture and organic impurities reduce Li Coulombic efficiency and increase cell variability. We classify impurities by generation pathway into retained intermediates, starting-material-derived analogues, side-reaction products, and purification-introduced residues. Distillation, adsorption, and reactive purification implicate water, alkoxide-derived byproducts, and amines as key performance-limiting species. However, excessive purification generates secondary impurities that degrade performance, revealing a removal–generation trade-off. Thermal, electrochemical, operando microcalorimetry, and online mass spectrometry analyses reveal impurity-dependent current-collector corrosion, heat release, gas evolution, and full-cell degradation. This route-resolved, source-to-consequence workflow provides a transferable qualification framework for electrolyte solvent scale-up.
