ABSTRACT
Electric eels generate electricity with a discharge voltage of up to 860 V under ionic gradients, providing a fascinating example to inspire viable and flexible power sources. However, hitherto reported eel-related devices are strictly restricted by complicated fabrication and environmental energy input. Herein, an electric-eel-type bi-ionic gradient battery (BGB) is performed by cationic and anionic polyelectrolyte hydrogels featuring simplified units and self-energy supply. Benefiting from ionic bonds with opposite charges in the polymer chain, bianion gradients as well as ion selective migration pathways are synchronously constructed and integrated units are enabled. As a result, an open-circuit voltage of 0.54 V and a short-circuit current density of 13 µA cm-2 are generated by a BGB unit. Moreover, a voltage output up to 60 V is derived from integrated BGB devices, demonstrating the potential to drive wearable and implantable electronics. In this case, these artificial electric systems could overcome the great challenges of environmentally friendly, biocompatible, low-cost, and soft power sources, providing in-depth insights into the development of clean and sustainable power generation technologies.
ABSTRACT
The aqueous zinc-ion battery is considered as one of the best alternatives to lithium-ion batteries due to its low cost and high safety. However, the inevitable dendrite growth, byproduct formation, and the side reactions have inhibited the application of aqueous zinc-ion batteries. In this work, the electronegative nitrogen and sulfur-codoped carbon dots (NSCDs) are proposed as an electrolyte additive to regulate the uniform distribution of zinc ions and inhibit the growth of dendrites. It was found that only a small amount of NSCD additive (0.2 mg mL-1) exerted a significant influence in electrochemical performance; the symmetrical cell can operate stably for 2000 h with a low voltage hysteresis of 33 mV at the current density of 1 mA cm-2, and a high Coulombic efficiency (CE) of 99.5% can be obtained after 250 cycles.
ABSTRACT
HIGHLIGHTS: The chemical process of local oxidation-partial reduction-deep coupling for stibnite reduction of carbon dots (CDs) is revealed by in-situ high-temperature X-ray diffraction. Sb2S3@xCDs anode delivers high initial coulombic efficiency in lithium ion batteries (85.2%) and sodium ion batteries (82.9%), respectively. C-S bond influenced by oxygen-rich carbon matrix can restrain the conversion of sulfur to sulfite, well confirmed by X-ray photoelectron spectroscopy characterization of solid electrolyte interphase layers helped with density functional theory calculations. CDs-induced Sb-O-C bond is proved to effectively regulate the interfacial electronic structure. The application of Sb2S3 with marvelous theoretical capacity for alkali metal-ion batteries is seriously limited by its poor electrical conductivity and low initial coulombic efficiency (ICE). In this work, natural stibnite modified by carbon dots (Sb2S3@xCDs) is elaborately designed with high ICE. Greatly, chemical processes of local oxidation-partial reduction-deep coupling for stibnite reduction of CDs are clearly demonstrated, confirmed with in situ high-temperature X-ray diffraction. More impressively, the ICE for lithium-ion batteries (LIBs) is enhanced to 85%, through the effect of oxygen-rich carbon matrix on C-S bonds which inhibit the conversion of sulfur to sulfite, well supported by X-ray photoelectron spectroscopy characterization of solid electrolyte interphase layers helped with density functional theory calculations. Not than less, it is found that Sb-O-C bonds existed in the interface effectively promote the electronic conductivity and expedite ion transmission by reducing the bandgap and restraining the slip of the dislocation. As a result, the optimal sample delivers a tremendous reversible capacity of 660 mAh g-1 in LIBs at a high current rate of 5 A g-1. This work provides a new methodology for enhancing the electrochemical energy storage performance of metal sulfides, especially for improving the ICE.
ABSTRACT
A hybrid shell material of hollow Nb2O5 microspheres has been engineered as an effective sulfur host for use in Li-S batteries. Of particular note is that the selected Nb2O5 not only exhibits ultrafast Li+ motion properties due to its unique room-and-pillar NbO6/NbO7 framework structure, but also demonstrates moderate polar affinities to the lithium polysulfides based on theoretical calculations.
