lyj1070144984

A high-performance Zn–S battery is achieved by employing a hybrid electrolyte using a low-cost protic solvent (ethylene glycol) as the co-solvent in water. The designed hybrid electrolyte not only can regulate water activity and suppress sulfur side reactions in aqueous electrolytes but also forms an in situ SEI layer on the Zn anode to facilitate reversible Zn stripping/plating.

Abstract

Rechargeable aqueous Zn/S batteries exhibit high capacity and energy density. However, the long-term battery performance is bottlenecked by the sulfur side reactions and serious Zn anode dendritic growth in the aqueous electrolyte medium. This work addresses the problem of sulfur side reactions and zinc dendrite growth simultaneously by developing a unique hybrid aqueous electrolyte using ethylene glycol as a co-solvent. The designed hybrid electrolyte enables the fabricated Zn/S battery to deliver an unprecedented capacity of 1435 mAh g⁻¹ and an excellent energy density of 730 Wh kg⁻¹ at 0.1 Ag⁻¹. In addition, the battery exhibits capacity retention of 70% after 250 cycles even at 3 Ag⁻¹. Moreover, the cathode charge–discharge mechanism studies demonstrate a multi-step conversion reaction. During discharge, the elemental sulfur is sequentially reduced by Zn to S²⁻ (S8→Sx2−→S22−+S2−)${{\rm{S}}_8}{\bm{ \to }}{\rm{S}}_{\rm{x}}^{2{\bm{ - }}}{\bm{ \to }}{\rm{S}}_2^{2{\bm{ - }}}{\bm{ + }}{{\rm{S}}^{2{\bm{ - }}}})$, forming ZnS. On charging, the ZnS and short-chain polysulfides will oxidize back to elemental sulfur. This electrolyte design strategy and unique multi-step electrochemistry of the Zn/S system provide a new pathway in tackling both key issues of Zn dendritic growth and sulfur side reactions, and also in designing better Zn/S batteries in the future.

Nature Communications, Published online: 06 December 2022; doi:10.1038/s41467-022-35158-9

We report a versatile method to make liquid metal composites by vigorously mixing gallium (Ga) with non-metallic particles of graphene oxide (G-O), graphite, diamond, and silicon carbide that display either paste or putty-like behavior depending on the volume fraction. Unlike Ga, the putty-like mixtures can be kneaded and rolled on any surface without leaving residue. By changing temperature, these materials can be stiffened, softened, and, for the G-O–containing composite, even made porous. The gallium putty (GalP) containing reduced G-O (rG-O) has excellent electromagnetic interference shielding effectiveness. GalP with diamond filler has excellent thermal conductivity and heat transfer superior to a commercial liquid metal–based thermal paste. Composites can also be formed from eutectic alloys of Ga including Ga-In (EGaIn), Ga-Sn (EGaSn), and Ga-In-Sn (EGaInSn or Galinstan). The versatility of our approach allows a variety of fillers to be incorporated in liquid metals, potentially allowing filler-specific "fit for purpose" materials.

A long‐chain polyethylene oxide (PEO) polymer is developed as an effective multifunctional electrolyte additive to effectively suppress Zn²⁺ ion transfer kinetics, smooth Zn²⁺ ion distribution, prevent gas generation, enabling stable Zn deposition. Stable cycling over 3000 h and high reversibility (Coulombic efficiency > 99.5%) of Zn anodes are demonstrated with PEO additives in 1 m ZnSO₄ aqueous electrolytes.

Abstract

Zn dendrites growth and poor cycling stability are significant challenges for rechargeable aqueous Zn batteries. Zn metal deposition‐dissolution in aqueous electrolytes is typically determined by Zn anode–electrolyte interfaces. In this work, the role of a long‐chain polyethylene oxide (PEO) polymer as a multifunctional electrolyte additive in stabilizing Zn metal anodes is reported. PEO molecules suppress Zn²⁺ ion transfer kinetics and regulate Zn²⁺ ion concentration in the vicinity of Zn anodes through interactions between ether groups of PEO and Zn²⁺ ions. The suppressed Zn²⁺ ion transfer kinetics and homogeneous Zn²⁺ ion distribution at the interface promotes dendrite‐free homogeneous Zn deposition. In addition, electrochemically inert PEO molecules adsorbed onto Zn anodes can protect the anode surfaces from H₂ generation and, thereby, enhance their electrochemical stability. Stable cycling over 3000 h and high reversibility (Coulombic efficiency > 99.5%) of Zn anodes is demonstrated in 1 m ZnSO₄ electrolyte with 0.5 wt% PEO. This finding provides helpful insights into the mechanism of Zn metal anodes stabilization by low‐cost multifunctional polymer electrolyte additives that stabilize interfacial reactions.

An intermediate derivative material with an amorphous structure is formed during the transformation of ZIF‐67 crystal to Co₃O₄ nanocrystal via a low‐temperature heat treatment for ZIF‐67 hollow spheres. As electrocatalysts for the oxygen evolution reaction and nonenzymatic glucose sensing, the amorphous derivative exhibits significantly better catalytic activity than crystalline Co₃O₄ samples.

Abstract

Increasing active sites is an effective method to enhance the catalytic activity of catalysts. Amorphous materials have attracted considerable attention in catalysis because of their abundant catalytic active sites. Herein, a series of derivatives is prepared via the low‐temperature heat treatment of ZIF‐67 hollow sphere at different temperatures. An intermediate product with an amorphous structure is formed during transformation from ZIF‐67 to Co₃O₄ nanocrystallines when ZIF‐67 hollow sphere is heat treated at 260 °C for 3 h. The chemical composition of the amorphous derivative is similar to that of ZIF‐67, and the carbon and nitrogen contents of the amorphous derivative are obviously higher than those of crystalline samples obtained at 270 °C or higher. As electrocatalysts for the oxygen evolution reaction (OER) and nonenzymatic glucose sensing, the amorphous derivative exhibits significantly better catalytic activity than crystalline Co₃O₄ samples. The amorphous sample as an OER catalyst has a low overpotential of 352 mV at 10 mA cm⁻². The amorphous sample as an enzyme‐free glucose sensing catalyst can provide a low detection limit of 3.9 × 10⁻⁶ m and a high sensitivity of 1074.22 µA mM⁻¹ cm⁻².

Al instead of Li: The recent developments of rechargeable aluminum battery systems and their limitations are discussed in this Review. It gives guidelines for better aluminum battery system design in terms of electrodes, electrolytes and electrodes/electrolyte interface.

Abstract

Aluminum battery systems are considered as a system that could supplement current lithium batteries due to the low cost and high volumetric capacity of aluminum metal, and the high safety of the whole battery system. However, first the use of ionic liquid electrolytes leading to AlCl₄ ⁻ instead of Al³⁺, the different intercalation reagents, the sluggish solid diffusion process and the fast capacity fading during cycling in aluminum batteries all need to be thoroughly explored. To provide a good understanding of the opportunities and challenges of the newly emerging aluminum batteries, this Review discusses the reaction mechanisms and the difficulties caused by the trivalent reaction medium in electrolytes, electrodes, and electrode–electrolyte interfaces. It is hoped that the Review will stimulate scientists and engineers to develop more reliable aluminum batteries.

A judicious in situ activating strategy is developed to concurrently boost the oxygen reduction/evolution activities of commercial carbon textiles without loading any other active materials and eventually transform such ubiquitous raw materials into low‐cost, efficient, robust, self‐standing, additive‐free, and bifunctional air electrodes for direct use in rechargeable liquid and flexible solid‐state Zn‐air batteries.

Abstract

An in situ strategy to simultaneously boost oxygen reduction and oxygen evolution (ORR/OER) activities of commercial carbon textiles is reported and the direct use of such ubiquitous raw material as low‐cost, efficient, robust, self‐supporting, and bifunctional air electrodes in rechargeable Zn‐air batteries is demonstrated. This strategy not only furnishes carbon textiles with a large surface area and hierarchical meso‐microporosity, but also enables efficient dual‐doping of N and S into carbon skeletons while retaining high conductivity and stable monolithic structures. Thus, although original carbon textile has rather poor catalytic activity, the activated textiles without loading other active materials yield effective ORR/OER bifunctionality and stability with a much lower reversible overpotential (0.87 V) than those of Pt/C (1.10 V) and RuO₂ (1.02 V) and many reported metal‐free bifunctional catalysts. Importantly, they can concurrently function as current collectors and as ORR/OER catalysts for rechargeable aqueous and flexible solid‐state Zn‐air batteries, showing excellent cell performance, long lifetime, and high flexibility.

Abstract