Highly Reversible Tin Film Anode Guided via Interfacial Coordination Effect for High Energy Aqueous Acidic Batteries.

Sn metal is a preferable choice as anode material for aqueous acidic batteries due to its acid-tolerance, non-toxicity, and ease of recycling. However, the large size and irregular deposition morphology of polyhedral Sn particles are bad for constructing stable and high-capacity Sn metal anode because of severe hydrogen evolution and metal shedding. To tackle this critical issue, 4-tert-octylphenol pentaethoxylate (POPE) is used as an electrolyte additive to generate a thin-film Sn anode with reversible stripping/plating behavior. POPE can not only induce homogeneous surface chemistry by adsorbing on the Sn surface via coordination bonds but also inhibit hydrogen evolution by modulating the solvation shell of Sn2+. The Sn film anode delivers improved electrochemical stability over 480 h with satisfactory rate performance and low polarization. Moreover, the as-assembled PbO2//Sn battery can also provide outstanding durability at 10 mAh cm-2. This work offers new inspiration for developing a reversible Sn metal film anode.

A weakly solvating electrolyte towards practical rechargeable aqueous zinc-ion batteries.

Structure deterioration and side reaction, which originated from the solvated H2O, are the main constraints for the practical deployment of both cathode and anode in aqueous Zn-ion batteries. Here we formulate a weakly solvating electrolyte to reduce the solvating power of H2O and strengthen the coordination competitiveness of SO42- to Zn2+ over H2O. Experiment results and theoretical simulations demonstrate that the water-poor solvation structure of Zn2+ is achieved, which can (i) substantially eliminate solvated-H2O-mediated undesirable side reactions on the Zn anode. (ii) boost the desolvation kinetics of Zn2+ and suppress Zn dendrite growth as well as structure aberration of the cathode. Remarkably, the synergy of these two factors enables long-life full cells including Zn/NaV3O8·1.5H2O, Zn/MnO2 and Zn/CoFe(CN)6 cells. More importantly, practical rechargeable AA-type Zn/NVO cells are assembled, which present a capacity of 101.7 mAh and stability of 96.1% capacity retention after 30 cycles at 0.66 C.

Unraveling the Mechanism of Cooperative Redox Chemistry in High-Efficient Zn2+ Storage of Vanadium Oxide Cathode.

The inferior capacity and cyclic durability of V2 O5 caused by inadequate active sites and sluggish kinetics are the main problems to encumber the widespread industrial applications of vanadium-zinc batteries (VZBs). Herein, a cooperative redox chemistry (CRC) as "electron carrier" is proposed to facilitate the electron-transfer by capturing/providing electrons for the redox of V2 O5 . The increased oxygen vacancies in V2 O5 provoked in situ by CRC offers numerous Zn2+ storage sites and ion-diffusion paths and reduces the electrostatic interactions between vanadium-based cathode and intercalated Zn2+ , which enhance Zn2+ storage capability and structural stability. The feasibility of this strategy is fully verified by some CRCs. Noticeably, VZB with [Fe(CN)6 ]3- /[Fe(CN)6 ]4- as CRC displays conspicuous specific capacity (433.3 mAh g-1 ), ≈100% coulombic efficiency and superb cyclability (≈3500 cycles without capacity attenuation). Also, the mechanism and selection criteria of CRC are specifically unraveled in this work, which provides insightful perspectives for the development of high-efficiency energy-storage devices.

Tendency Regulation of Competing Reactions Toward Highly Reversible Tin Anode for Aqueous Alkaline Batteries.

Investigating dendrite-free stripping/plating anodes is highly significant for advancing the practical application of aqueous alkaline batteries. Sn has been identified as a promising candidate for anode material, but its deposition/dissolution efficiency is hindered by the strong electrostatic repulsion between Sn(OH)3 - and the substrate. Herein, this work constructs a nondense copper layer which serves as stannophile and hydrogen evolution inhibitor to adjust the tendency of competing reactions on Sn foil surface, thus achieving a highly reversible Sn anode. The interactions between the deposited Sn and the substrates are also strengthened to prevent shedding. Notably, the ratio of Sn redox reaction is significantly boosted from ≈20% to ≈100%, which results in outstanding cycling stability over 560 h at 10 mA cm-2 . A Sn//Ni(OH)2 battery device is also demonstrated with capacities from 0.94 to 22.4 mA h cm-2 and maximum stability of 1800 cycles.

Ultralow Charge Voltage Triggering Exceptional Post-Charging Antibacterial Capability of Co3 O4 /MnOOH Nanoneedles for Skin Infection Treatment.

The post-charging antibacterial therapy is highly promising for treatment of Gram-negative bacterial wound infections. However, the therapeutic efficacy of the current electrode materials is yet unsatisfactory due to their low charge storage capacity and limited reactive oxygen species (ROS) yields. Herein, the design of MnOOH decorated Co3 O4 nanoneedles (MCO) with exceptional post-charging antibacterial effect against Gram-negative bacteria at a low charge voltage and their implementation as a robust antibacterial electrode for skin wound treatment are reported. Taking advantaging of the increased active sites and enhanced OH- adsorption capability, the charge storage capacity and ROS production of the MCO electrode are remarkably boosted. As a result, the MCO electrode after charging at an ultralow voltage of 1.4 V gives a 5.49 log and 5.82 log bacterial reduction in Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) within an incubation time of only 5 min, respectively. More importantly, the antibacterial efficiency of the MCO electrode against multi-drug resistant (MDR) bacteria including Klebsiella pneumoniae (K. pneumoniae) and Acinetobacter baumannii (A. baumannii) also reaches 99.999%. In addition, the MCO electrode exhibits excellent reusability, and the role of extracellular ROS in enhancing post-charging antibacterial activity is also unraveled.

Compacting Electric Double Layer Enables Carbon Electrode with Ultrahigh Zn Ion Storage Capability.

Carbon-based cathodes for aqueous zinc ion hybrid supercapacitors (ZHSCs) typically undergo low Zn ion storage capability due to their electric double layer capacitance (EDLC) energy storage mechanism that is restricted by specific surface area and thickness of electric double layer (EDL). Here, we report a universal surface charge modulation strategy to effectively enhance the capacitance of carbon materials by decreasing the thickness of EDL. Amino groups with lone pair electrons were chosen to increase the surface charge density and enhanced the interaction between carbon electrode and Zn ions, thus effectively compacting the EDL. Consequently, amino functionalized porous carbon based ZHSCs can deliver an ultrahigh capacity of 255.2 mAh g-1 along with excellent cycling stability (95.5 % capacity retention after 50 000 cycles) in 1 M ZnCl2 electrolyte. This study demonstrates the feasibility of EDL modified carbon as Zn2+ storage cathode and great prospect for constructing high performance ZHSCs.

Methods for Rational Design of Advanced Zn-Based Batteries.

Rechargeable aqueous zinc-based batteries (AZBs) have received massive attention as promising contenders for the future large-scale energy storage due to their low cost, inherent safety, and abundant resources. However, the insufficient energy density and poor stability have become the key to hinder their further application. As is well known, the energy densities (E, Wh kg-1 ) of AZBs are determined by the specific capacity (mAh g-1 ) and output voltage (V). Given the fixed redox potential and capacity of the Zn metal anode, the energy density of AZBs is mainly determined by the cathode material, and the rich material systems of the cathode provide more possibilities to this field. Meanwhile, the methods to improve the stability and performance of the Zn anodes have gained more and more attention due to the severe Zn dendrite growth that can pierce the separator and lead to short-circuiting of the cell. Therefore, in this review, we comprehensively summarize the rational design methods in optimizing the cathode, anode, and device architecture, and classic examples of each catalogue are discussed in details as well. Last, the issues and outlook for further development of high performance AZBs are also presented.

Iron decorated ultrathin cobaltous hydroxide nanoflakes with impressive electrochemical reactivity for aqueous Zn batteries.

The main bottlenecks of current Co-based cathodes are their relatively low capacity and inferior reversibility. Here, we report Fe decorated cobaltous hydroxide (FCO) nanoflakes with vastly improved capacity and cycling stability via an efficient surface activation approach, which function as an advanced cathode for Co-Zn batteries. In comparison with the pristine cobaltous hydroxide (CO), the FCO sample owns higher electrochemical reactivity and a larger electrochemical surface area, endowing it with impressive electrochemical properties.

Intrinsic Carbon Defects Induced Reversible Antimony Chemistry for High-Energy Aqueous Alkaline Batteries.

Developing high-capacity, dendrite-free, and stable anode materials for robust aqueous alkaline batteries (AABs) is an ongoing challenge. Antimony (Sb) is predicated as an attractive anode material, but it still suffers from low capacity and poor stability caused by the obstructed kinetic behavior and uncontrollable nucleation for SbO2 - . Herein, designing a new defect-modified carbon skeleton (D-CS), a highly reversible Sb anode with ultralong cycling stability is realized at practical levels of capacity and high depth of discharge (DOD). The abundant intrinsic carbon defects can effectively form positive charge centers to weaken electrostatic repulsion between SbO2 - and electrode surface, facilitating the fast ion kinetics and provide generous controllable nucleation sites. In addition, the uniform electric field distribution of the D-CS induces manageable plating and stripping of the Sb metal, which effectively boosts its electrochemical reversibility and restrains adverse reactions. Accordingly, the Sb/D-CS electrode achieves a long cycle life of over 500 h with a capacity of 2 mAh cm-2 . Even at an ultrahigh capacity of 10 mAh cm-2 , it can still work stably up to 40 h. Furthermore, its feasibility as advanced anode in AABs is also confirmed by assembled Ni//Sb/D-CS full batteries with an ultrahigh capacity of 13.5 mAh cm-2 and a considerable stability of 4500 cycles.

A COF-Like N-Rich Conjugated Microporous Polytriphenylamine Cathode with Pseudocapacitive Anion Storage Behavior for High-Energy Aqueous Zinc Dual-Ion Batteries.

Conducting polymers with good electron conductivity and rich redox functional groups are promising cathode candidates for constructing high-energy aqueous zinc batteries. However, the glaring flaw of active-site underutilization impairs their electrochemical performance. Herein, we report a poriferous polytriphenylamine conjugated microporous polymer (CMP) cathode capable of accommodating Cl- anions in a pseudocapative-dominated manner for energy storage. Its specific 3D, covalent-organic-framework-like conjugated network ensures high accessibility efficacy of N active sites (up to 83.2% at 0.5 A g-1 ) and distinct physicochemical stability (87.6% capacity retention after 1000 cycles) during repeated charging/discharging courses. Such a robust CMP electrode also leads to a zinc dual-ion battery device with a high energy density of 236 W h kg-1 and a maximum power density of 6.8 kW kg-1 , substantially surpassing most recently reported organic-based zinc batteries. This study paves the way for the rational design of advanced CMP-based organic cathodes for high-energy devices.

Linker Defects Triggering Boosted Oxygen Reduction Activity of Co/Zn-ZIF Nanosheet Arrays for Rechargeable Zn-Air batteries.

The poor electronic conductivity and low intrinsically electrocatalytic activity of most metal-organic frameworks (MOFs) greatly limit their direct applications as oxygen reduction reaction (ORR) electrocatalysts. In this work, it is reported that introduction of linker defects can effectively trigger the ORR activity of leaf-shaped zeolitic imidazolate framework (ZIF) by increasing the intrinsic activity of metal sites and electrical conductivity. Experimental results show that part of imidazole molecules is successfully removed from ZIF after a low-temperature thermal treatment without destroying its structure integrity, resulting in the formation of unsaturated metal sites and faster electron transport rate. Consequently, the ZIF with imidazole molecules defects (D-ZIF) exhibits a superior ORR activity than the pristine ZIF, possessing an onset potential of 0.86 V and higher half-wave potential of 0.60 V. Furthermore, the home-made Zn-air batteries with D-ZIF as air cathode exhibit high open-circuit voltage and well cycling stability. The developed linker-deficient modulation strategy can provide a new prospect to enable MOF-based electrocatalysts with efficient catalytic activity.