Carbon Nitride Pillared Vanadate Via Chemical Pre-Intercalation Towards High-Performance Aqueous Zinc-Ion Batteries.

Vanadium based compounds are promising cathode materials for aqueous zinc (Zn)-ion batteries (AZIBs) due to their high specific capacity. However, the narrow interlayer spacing, low intrinsic conductivity and the vanadium dissolution still restrict their further application. Herein, we present an oxygen-deficient vanadate pillared by carbon nitride (C3 N4 ) as the cathode for AZIBs through a facile self-engaged hydrothermal strategy. Of note, C3 N4 nanosheets can act as both the nitrogen source and pre-intercalation species to transform the orthorhombic V2 O5 into layered NH4 V4 O10 with expanded interlayer spacing. Owing to the pillared structure and abundant oxygen vacancies, both the Zn2+ ion (de)intercalation kinetics and the ionic conductivity in the NH4 V4 O10 cathode are promoted. As a result, the NH4 V4 O10 cathode delivers exceptional Zn-ion storage ability with a high specific capacity of about 370 mAh g-1 at 0.5 A g-1 , a high-rate capability of 194.7 mAh g-1 at 20 A g-1 and a stable cycling performance of 10 000 cycles.

Atomically Dispersed Cu in Zeolitic Imidazolate Framework Nanoflake Array for Dendrite-Free Zn Metal Anode.

Aqueous Zn metal batteries (AZMBs) have been considered as a promising alternative to the existing Li-ion batteries. Nevertheless, the large-scale application of the AZMBs is restricted by the dendrite formation and side reactions within the Zn metal anodes (ZMAs) during cycling. Herein, an atomically dispersed Cu in leaf-like Zn-coordinated zeolitic imidazolate framework (ZIF-L) nanoflakes on Ti mesh (CuZIF-L@TM) as ZMA host is developed. The 3D conductive network formed by the interconnected ZIF-L nanoflakes can reduce the local current density and homogenize the electric field distribution. Moreover, experimental data and theoretical calculations reveal the Cu single atoms within the ZIF-L can serve as the zincophilic sites to facilitate the Zn deposition. As expected, the CuZIF-L@TM host enables a homogeneous Zn deposition on the surface without dendrites. The resultant CuZIF-L@TM/Zn electrode shows stable Zn plating/stripping over 1100 h at 1 mA cm-2 with a low voltage hysteresis of about 50 mV. As a proof of concept, a full cell based on the designed CuZIF-L@TM/Zn anode shows a stable cycling performance over 1000 cycles.

Formation of Super-Assembled TiOx /Zn/N-Doped Carbon Inverse Opal Towards Dendrite-Free Zn Anodes.

Uncontrolled growth of Zn dendrites and side reactions are the major restrictions for the commercialization of Zn metal anodes. Herein, we develop a TiOx /Zn/N-doped carbon inverse opal (denoted as TZNC IO) host to regulate the Zn deposition. Amorphous TiOx and Zn/N-doped carbon can serve as the zincophilic nucleation sites to prevent the parasitic reactions. More importantly, the highly ordered IO host homogenizes the local current density and electric field to stabilize Zn deposition. Furthermore, the three-dimensional open networks could regulate Zn ion flux to enable stable cycling performance at large current densities. Owing to the abundant zincophilic sites and the open structure, granular Zn deposits could be realized. As expected, the TZNC IO host guarantees the steady Zn plating/stripping with a long-term stability over 450 h at the current density of 1 mA cm-2 . As a proof-of-concept demonstration, a TZNC@Zn||V2 O5 full cell shows long lifespan over 2000 cycles at 5.0 A g-1 .

Decoration of Ag Species into Reduced Graphene Oxide Foam as a Superelastic and Robust Host toward Stable Zn Metal Anodes under Dwell-Fatigue Condition.

Deep-sea equipment usually operates under dwell-fatigue condition, which means the equipped energy storage devices must survive under the changing pressure. Special mechanical designs should be considered to maintain the electrochemical performance of electrodes under this extreme condition. In this work, an effective assembly strategy is proposed to accommodate the dwell-fatigue loading using Ag decorated reduced graphene oxide (rGO) foam (denoted as AGF) as a superelastic and robust Zn host. The wet-press assembly process enables the formation of highly porous and robust framework. The strong synergetic effect between rGO and Ag further guarantees AGF's superelasticity and ultrahigh mechanical strength. Meanwhile, the homogeneously distributed Ag species on the rGO sheets act as zincophilic sites to effectively facilitate Zn plating. Furthermore, AGF offers enough space to address the expansion during the charge and discharge cycles. As expected, the symmetrical cell using this AGF@Zn host demonstrates a long lifespan over 400 h at a depth-of-discharge of 50%. It is worth mentioning that the superelastic AGF host realizes stable Zn plating/stripping under varying pressures.

Ternary-salt solid polymer electrolyte for high-rate and long-life lithium metal batteries.

A ternary-salt solid polymer electrolyte (TS-SPE) consisting of LiPF6-LiTFSI-LiFSI salts and poly(1,3-dioxolane) is created by in situ polymerization. The TS-SPE possesses high ionic conductivity, high Li+ ion transference number, and stable SEI with low interfacial impedance, thereby realizing excellent rate performance and long-life stability in Li metal batteries.

Nitrogen-Doped Carbon Fibers Embedded with Zincophilic Cu Nanoboxes for Stable Zn-Metal Anodes.

The practical application of Zn-metal anodes (ZMAs) is mainly impeded by the limited lifespan and low Coulombic efficiency (CE) resulting from the Zn dendrite growth and side reactions. Herein, a 3D multifunctional host consisting of N-doped carbon fibers embedded with Cu nanoboxes (denoted as Cu NBs@NCFs) is rationally designed and developed for stable ZMAs. The 3D macroporous configuration and hollow structure can lower the local current density and alleviate the large volume change during the repeated cycling processes. Furthermore, zincophilic Cu and in-situ-formed Cu-Zn alloy can act as homogeneous nucleation sites to minimize the Zn nucleation overpotential, further guiding uniform and dense Zn deposition. As a result, this Cu NBs@NCFs host exhibits high CE of Zn plating/stripping for 1000 cycles. The Cu NBs@NCFs-Zn electrode shows low voltage hysteresis and prolonged cycling life (450 h) with dendrite-free behaviors. As a proof-of-concept demonstration, a Zn-ion full cell is fabricated based on this Cu NBs@NCFs-Zn anode, which demonstrates decent rate capability and improved cycling performance.