Quantifying Asymmetric Zinc Deposition: A Guide Factor for Designing Durable Zinc Anodes.

Zinc metal is recognized as the most promising anode for aqueous energy storage but suffers from severe dendrite growth and poor reversibility. However, the coulombic efficiency lacks specificity for zinc dendrite growth, particularly in Zn||Zn symmetric cells. Herein, a novel indicator (fD) based on the characteristic crystallization peaks is proposed to evaluate the growth and distribution of zinc dendrites. As a proof of concept, triethylenetetramine (TETA) is adopted as an electrolyte additive to manipulate the zinc flux for uniform deposition, with a corroborating low fD value. A highly durable zinc symmetric cell is achieved, lasting over 2500 h at 10 mA cm-2 and 400 h at a large discharge of depth (10 mA cm-2, 10 mAh cm-2). Supported by the low fD value, the Zn||TETA-ZnSO4||MnO2 batteries overcome the sudden short circuit and fast capacity fading. The study provides a feasible method to evaluate zinc dendrites and sheds light on the design of highly reversible zinc anodes.

Highly Reversible Positive-Valence Conversion of Sulfur Chemistry for High-Voltage Zinc-Sulfur Batteries.

Sulfur is a promising conversion-type cathode for zinc batteries (ZBs) due to its high discharge capacity and cost-effectiveness. However, the redox conversion of multivalent S in ZBs is still limited, only having achieved S0/S2- redox conversion with low discharge voltage and poor reversibility. This study presents significant progress by demonstrating, for the first time, the reversible S2-/S4+ redox behavior in ZBs with up to six-electron transfer (with an achieved discharge capacity of ≈1284 mAh g-1) using a highly concentrated ClO4 --containing electrolyte. The developed succinonitrile-Zn(ClO4)2 eutectic electrolyte stabilizes the positive-valence S compound and contributes to an ultra-low polarization voltage. Notably, the achieved flat discharge plateaus demonstrate the highest operation voltage (1.54 V) achieved to date in Zn‖S batteries. Furthermore, the high-voltage Zn‖S battery exhibits remarkable conversion dynamics, excellent cycling performance (85.7% capacity retention after 500 cycles), high efficiency (98.4%), and energy density (527 Wh kg S -1). This strategy of positive-valence conversion of sulfur represents a significant advancement in understanding sulfur chemistry in batteries and holds promise for future high-voltage sulfur-based batteries.

Geochemical distribution and mineralogy of heavy metals in the gasification residue of coal-waste activated carbon-slurry: Insights into leaching behavior.

Here, a novel approach to the detoxification and reuse of waste activated carbon (WAC) through co-gasification with coal-water slurry (CWS) is proposed. To evaluate the harmlessness to the environment of this method, the mineralogical composition, leaching characteristics, and geochemical distribution of heavy metals were investigated, enabling the leaching behavior of heavy metals in gasification residues to be explained. The results showed that the gasification residue of coal-waste activated carbon-slurry (CWACS) contained higher concentrations of Cr, Cu, and Zn, while those of Cd, Pb, As, Hg, and Se were well below 100 µg/g. Further, the spatial distributions of Cr, Cu, and Zn in the mineral phases of the gasification residue of CWACS were relatively uniform overall, and no obvious regional enrichment was observed. The leaching concentrations of various heavy metals in the gasification residues of the two CWACS samples were all lower than the standard limit. Following the co-gasification of WAC with CWS, the stability of the heavy metals in the environment was enhanced. Meanwhile, the gasification residues of the two CWACS samples showed no environmental risk for Cr, low environmental risk for Pb and Hg, and only a moderate environmental risk for Cd, As, and Se.

Organic Monomolecular Layers Enable Energy-Level Matching for Efficient Hole Transporting Layer Free Inverted Perovskite Solar Cells.

High-efficiency hole transport layer free perovskite solar cells (HTL-free PSCs) with economical and simplified device structure can greatly facilitate the commercialization of PSCs. However, eliminating the key HTL in PSCs results usually in a severe efficiency loss and poor carrier transfer due to the energy-level mismatching at the indium tin oxide (ITO)/perovskite interface. In this study, we solve this issue by introducing an organic monomolecular layer (ML) to raise the effective work function of ITO with the assistance of an interface dipole created by Sn-N bonds. The energy-level alignment at the ITO/perovskite interface is optimized with a barrier-free contact, which favors efficient charge transfer and suppressed nonradiative carrier recombination. The HTL-free PSCs based on the ML-modified ITO yield an efficiency of 19.4%, much higher than those of HTL-free PSCs on bare ITO (10.26%), comparable to state-of-the-art PSCs with a HTL. This study provides an in-depth understanding of the mechanism of interfacial energy-level alignment and facilitates the design of advanced interfacial materials for simplified and efficient PSC devices.