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A surface-grafting strategy of molecular brushes is demonstrated to create a robust ion-regulating interface toward calendar-life Zn anodes with a high Coulombic efficiency of 99.9% and ultralong cyclability over 2500 h at 10 mA cm−2.

A universal and versatile metal–organic complex interphase strategy is proposed as a splendid dendrite and corrosion inhibitor for achieving ultrastable Zn anodes with substantially improved Coulombic efficiency and extended cycling lifetime.

Rechargeable aqueous zinc-ion batteries hold great prospects in grid-level energy storage due to their virtues of good safety, low cost and eco-friendliness. However, the sluggish intercalation kinetics of divalent Zn2+ makes the exploration of a suitable Zn2+-host cathode being a formidable challenge. In this work, we unveil the crucial role of crystal water on boosting the Zn2+ intercalation kinetics of layered MoS2 host. The crystal water molecules could function as structural pillars to enlarge the interlayer distance of MoS2 and improve the surface hydrophilicity. Notably, a substantially-enhanced Zn2+ intercalation kinetics is realized by accelerating the charge-transfer transportation and Zn2+ diffusivity. Consequently, the hydrated MoS2 nanosheets enable efficacious Zn2+ insertion/extraction to achieve a high specific capacity of 182 mAh g−1 at 0.1 A g−1 and superior rate/cycling performance. The present study will enlighten the water implantation strategy to engineering hydrated cathode materials toward high-performance aqueous batteries.

Rechargeable aqueous zinc-ion batteries (ZIBs) are considered to be one of the most promising energy storage devices for grid-scale applications due to their high safety, eco-friendliness, and low cost. In recent years, enormous efforts have been devoted to developing a great number of high-efficient cathodes, anodes, and electrolytes for improving the electrochemical properties of aqueous ZIBs. However, the as-documented ZIBs and their associated energy storage mechanisms are still in infancy and need to be further investigated for real practice. To expedite the development of ZIBs, this review will offer a comprehensive summary and a detailed discussion of the significant progress and breakthroughs. A brief overview of the battery configuration and various energy storage mechanisms are first introduced. The following emphasis will be mainly dedicated to discussing different design strategies regarding cathodes, anodes, and electrolytes, aiming to provide insightful design principles for future research activities from a fundamental perspective. Finally, the current challenges of developing high-performance ZIBs and their opportunities for practical viability are discussed.

Hierarchically two-dimensional (2D) heteroarchitecture with ultrafine MoS2 nanosheets vertically patterned on graphene is developed by using a facile solvothermal method. It is revealed that the strong interfacial interaction between acidic Mo precursors and graphene oxides allows for uniform and tight alignment of edge-oriented MoS2 nanosheets on planar graphene. The unique sheet-on-sheet architecture is of grand advantage in synergistically utilizing the highly conductive graphene and the electroactive MoS2, thus rendering boosted reaction kinetics and robust structural integrity for energy storage. Consequently, the heterostructured MoS2@graphene exhibits impressive Li/Na-ion storage properties, including high-capacity delivery and superior rate/cycling capability. The present study will provide a positive impetus on rational design of 2D metal sulfide/graphene composites as advanced electrode materials for high-efficient alkali–metal ion storage.

Hierarchically two-dimensional (2D) heteroarchitecture with ultrafine MoS2 nanosheets vertically patterned on graphene is developed by using a facile solvothermal method. It is revealed that the strong interfacial interaction between acidic Mo precursors and graphene oxides allows for uniform and tight alignment of edge-oriented MoS2 nanosheets on planar graphene. The unique sheet-on-sheet architecture is of grand advantage in synergistically utilizing the highly conductive graphene and the electroactive MoS2, thus rendering boosted reaction kinetics and robust structural integrity for energy storage. Consequently, the heterostructured MoS2@graphene exhibits impressive Li/Na-ion storage properties, including high-capacity delivery and superior rate/cycling capability. The present study will provide a positive impetus on rational design of 2D metal sulfide/graphene composites as advanced electrode materials for high-efficient alkali–metal ion storage.

Rechargeable zinc-ion batteries based on Zn/MnO2 in neutral aqueous electrolytes are promising for grid-scale energy storage applications owing to their favorable merits of high safety, low cost and environmental benignity. However, MnO2 cathodes are subjected to the challenging issues of poor cyclability and low rate capability. Herein, we report a facile chemical method for the preparation of mesoporous MnO2 flower-like nanospheres with the layered framework stabilized by hydrated Zn2+ pillars. The MnO2 cathode could deliver a reversible specific capacity of 358 mA h g−1 at 0.3 A g−1 after 100 cycles, a high rate capacity of 124 mA h g−1 at 3.0 A g−1, and excellent operating stability over 2000 cycles. Structural and morphological investigations demonstrate an energy storage mechanism of co-insertion/extraction of H+ and Zn2+ accompanied by deposition/dissolution of zinc sulfate hydroxide hydrate flakes on the electrode surface. The superior electrochemical performance makes the zinc ion stabilized MnO2 promising for high capacity and long lifespan zinc-ion batteries.

Electrode materials with high tap density are important for their practical application to achieve high volumetric energy density Li-ion batteries. In this work, large-scale fabrication of microsized carbon/MnOx/carbon nanotube composites by a low-cost spray-drying method is reported. The carbon/MnOx/carbon nanotube is characteristic of microspherical morphology consisting of interconnected carbon nanotubes and nano-MnOx with an exterior carbon coating. The micropacking enables the composite to exhibit a tap density as high as 2.54 g cm−3. When evaluated as anode materials for Li-ion batteries, the high-tap-density carbon/MnOx/carbon nanotube electrode delivers a specific capacity of 927 mAh g−1 after 100 cycles, corresponding to an ultrahigh volumetric capacity of 2355 mAh cm−3. The carbon network also has dual-functions of excellent electrical conductivity and good mechanical elasticity for the MnOx to sustain superior rate and cycling properties. The scale-up production method provides a reliable practical avenue of fabricating high-tap-density metal-oxide materials for high-performance Li-ion batteries.

SnS-based materials show great potential as high-capacity anode candidates of Li-ion batteries owing to their dual-mechanisms of conversion and alloying reactions. However, the practical application is substantially hampered by its poor electrochemical utilization and stability. Herein, we demonstrate three-dimensional SnS/C microflowers prepared by a controllable self-polymerization and carbonization of polydopamine-coated SnS 2 precursors. The building nanosheet consists of uniform encapsulation of ultrafine SnS nanoparticles into the conductive carbon framework. Benefiting from the nanoscaled building blocks and the porous three-dimensional architecture, the carbon-encapsulated nano-SnS microflowers show a significant enhancement in the electrochemical reaction kinetics and durability. As a result, the hybrid exhibits a high specific capacity of ∼1000 mAh g −1 at 0.1 A g −1 with a high initial Coulombic efficiency of 84.2%, good rate capability, and stable cyclability. The present work provides a reliable strategy for the rational fabrication of carbon-encapsulated SnS composites for high-performance Li-ion batteries.

Lithium-sulfur (Li-S) batteries represent an attractive energy storage technology for the employment in next-generation high-energy–density rechargeable batteries. The main challenge is to increase the electrochemical utilization and stabilization of sulfur cathodes by mitigating the undesirable soluble polysulfide shuttle problem. Herein, a zinc selenide/carbon hybrid (ZnSe/C) is constructed as a regulator of commercial polypropylene (PP) separator to modify the sulfiphilicity of polysulfide species. It is revealed that the polar ZnSe/C hybrid greatly inhibits the shuttling effect by strong chemisorption and thereafter fast electrocatalytic transformation of polysulfides. Accordingly, the ZnSe/C-modified PP separator could kinetically expedite the redox reaction and effectively promotes the utilization and confinement of the active sulfur in the cathode side. As a consequence, the ZnSe/C-PP-cell exhibits excellent electrochemical properties, including an impressive capacity delivery of 1458/605 mAh g−1 at 0.1 C/5 C and long lifetime with 608 mAh g−1 retained after 1000 cycles at 1 C. This study paves a rational pathway for designing and propelling transition-metal-selenide electrocatalysts toward the practical application of Li-S batteries.

Rechargeable aqueous Zn-ion batteries have shown considerable potential for stationary grid-scale energy storage systems owing to their characteristics of low cost and non-pollution. Nevertheless, the development of high-performance cathode materials is still a formidable challenge. In this work, for the first time, we report a superior silver vanadate (β-AgVO3) cathode for Zn-ion batteries, and demonstrate the fundamental Zn2+ storage mechanism in detail. In sharp contrast to the previously-reported layered vandium-based materials, the β-AgVO3 cathode experiences an initial phase transition to form a layered Zn3V2O7(OH)2·2H2O through a displacement/reduction reaction of Zn2+/Ag+ in the first discharge process. The in situ generated Ag0 along with the residual Ag+ and structural water within the framework afford high electronic/ionic conductivity, thus enabling enhanced Zn2+ intercalation/deintercalation kinetics in the layered phase. As a consequence, the cathode can deliver remarkable rate performance (103 mAh g-1 at 5000 mA g-1) and long-term cycling stability (95 mAh g-1 after 1000 cycles at 2000 mA g-1). The present study offers a totally new insight into the exploration of non-layered-structured vandium-based cathodes for high performance Zn-ion batteries.

A novel composite anode is prepared by mixing zinc particles with activated carbon (AC) to improve the cycle performance of the neutral rechargeable zinc ion batteries. Galvanostatic charge/discharge cycling tests indicate that the capacity retention of the cell with adding 12 wt% activated carbon in Zn anode is 85.6% after 80 cycles, which is much higher than that of 56.7% for the cell using unmodified Zn anode. X-ray diffraction analysis indicates that the addition of activated carbon can suppress the formation of inactive basic zinc sulfates (Zn4SO4(OH)6nH20). Morphology, elemental mapping and N2 adsorption and desorption measurements indicate that the pores of activated carbon can accommodate the deposition of Zn dendrites and insoluble anodic products. As a result, the cycle stability of the Zn anode has been greatly enhanced by activated carbon modification.

The rod-like manganese dioxide (MnO2)/acid-treated carbon nanotube (a-CNT) nanocomposites have been synthesized by a simple co-precipitation method. The MnO2 nanorod with the diameter of about 10 nm and length of 50∼120 nm is in-situ deposited on the surface of acid-treated CNT through the redox reaction of KMnO4 and Mn(CH3COO)2·4H2O. Results show that the electron transfer efficiency of the MnO2/a-CNT nanocomposites is greatly enhanced and results in a high electrical conductivity. The energy storage mechanism of as-prepared MnO2/a-CNT in mild aqueous electrolyte (ZnSO4 and MnSO4) is associated with the insertion/extraction of zinc ion into/from the tunnels of crystalline α-MnO2. The composites display both excellent storage properties with zinc ions (∼400 mAh·g−1 at 1 A·g−1) and reversibility at various current rates (∼100% coulombic efficiency after 500 charge/discharge cycles). The MnO2/a-CNT nanocomposites are rather promising cathode material for high performance rechargeable zinc ion batteries.

Manganese oxides represent a class of promising cathode materials for rechargeable aqueous zinc-ion batteries (ZIBs) due to their high energy density, safety, low cost, eco-friendliness and non-toxicity. However, manganese monooxide (MnO) is considered to be inactive for Zn2+ energy storage. Herein, for the first time, we demonstrate the possible application of commercial MnO microsized particles as cathodes for high performance ZIBs. It is interesting to note that electrochemical activation (or oxidation) is observed during the initial charging process, which leads to the formation of porous layered-type MnO2 nanosheets surrounding the MnO surface. As a result, the activated cathode could deliver a maximum specific capacity of 330 mAh g−1 in ZnSO4 aqueous electrolyte at a current density of 0.1 A g−1. In addition, the underlying energy storage mechanism is systematically investigated. The present work provides a new insight into the electrochemical activation strategy for developing advanced cathodes for high-performance zinc-ion batteries.

Six samples of α-MnO2 with different K ion contents are synthesized by using KMnO4 and Mn(CH3COO)2·4H2O with different pH values at room temperature. The samples are labeled as Mx where x denotes the pH value. The anomalous effect of K ion content on the electrochemical capacitance properties of amorphous MnO2 is investigated systematically. It is found that with the increase of the K ion content, the MnO2 nanospheres form a more dense aggregates, the surface area dramatically decreases from 273 (M2) to 14 m2 g−1 (M12), and pore volume decreases from 0.349 (M2) to 0.014 cm3 g−1 (M12). The specific capacitance (SC) is decreased by 17.6% from 157 (M2) to 131 F g−1 (M12). In addition, the SC values are greatly influenced by the molar ratio of K to Mn in the range of 0–0.4. And it is found that part of K ions in the MnO2 tunnels can be replaced by Na ions during electrochemical reaction. Finally, an appropriate explanation of the effect of K ion content on the SC values is provided.

A small amount of cations such as Li + , Na + , K + , or NH 4 + is required to stabilize the tunnels during the formation of MnO 2 . Here, the effect of the content of K ion on crystalline state and capacitance behavior of MnO 2 are investigated. It is found that with the content of K ion increasing, manganese dioxide is more likely to maintain amorphous, while adding Li + , Na + , or NH 4 + has no such effect. Adding K ion not only delays the conversion of manganese dioxide crystalline, but also delays the phase transformation temperature, which causes the big difference of specific capacitance value from 58 F g −1 for H2/400 to 124 F g −1 for K12/400. Furthermore, the morphology, special surface area, and pore data change dramatically from H2/400 to K12/400. These results have important implications for the characterization of MnO 2 in supercapacitor applications.

α-, β-, γ-, and δ-types manganese dioxide (MnO 2 ) with different tunnel structures and morphologies have been successfully synthesized by a common liquid co-precipitation method based on the redox reactions of Mn 4+ and Mn 2+ . The crystalline tunnel structure, particle size, and morphology of the manganese dioxides have been characterized by X-ray diffraction and scanning electron microscopy. It is found that the morphology of as-prepared MnO 2 changes with the concentration of raw materials. Depending on the procedure of preparation, spherical particles about 20 nm in diameter, nanorods of 40–100 nm in length and about 20 nm in diameter, or interlocked nanosheet of 10–20 nm in thickness are formed. The effect of crystallographic forms of MnO 2 on Zn 2+ ion storage properties has been revealed. The electrochemical performances of the α-, β-, γ-, and δ-MnO 2 were characterized by the galvanostatic charge–discharge and cyclic voltammetry tests. The δ-MnO 2 shows the highest specific capacity (269 mAh g −1 ) in the new zinc battery system Zn|ZnSO 4 (aq)|MnO 2 .

Formation and conversion mechanisms between single-crystal gamma-MnOOH and manganese oxides had investigated systematically. Without extra surfactant or template, α-MnO2 nanorods and prismatic single crystalline γ-MnOOH rods had been synthesized under hydrothermal treatment in this study. The formation and conversion mechanisms of prismatic γ-MnOOH rod were investigated by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It was found that the formation process includes three evolution stages: (1) formation of α-MnO2 nanorods whiskers; (2) transformation from α-MnO2 nanorods to prismatic γ-MnOOH rods by a dissolution-growth-recrystallization process; and (3) preferred growth on ( 1 1 1 ¯ ) crystal plane. In addition, β-MnO2, Mn2O3 or Mn3O4 rods could be obtained by calcination of the γ-MnOOH rods at different temperatures, which indicated that γ-MnOOH is an important precursor for preparing manganese oxides. The morphology and dimension of γ-MnOOH rods remained unchanged after converted to β-MnO2, Mn2O3 and Mn3O4.

The co-existence of two mechanisms, the surface chemisorption mechanism (SCM) and the tunnel storage mechanism (TSM), for the charge storage of MnO 2 is investigated. Sample α-MnO 2 whose tunnels (2 × 2) are almost vacant is synthesized by chemical co-precipitation technique. To verify whether the charge storage of as-prepared α-MnO 2 involves the charges based on the SCM besides the TSM, Ba 2+ and K + are intercalated into the tunnels of α-MnO 2 by refluxing and samples Ba-MnO 2 and K-MnO 2 are obtained, respectively. By powder X-ray diffraction, ICP and the extraction test, it is confirmed that Ba 2+ and K + occupy the tunnels and are difficult to remove. By electrochemical analyses, we have found that the charge storage of Ba-MnO 2 and K-MnO 2 basically depends on the SCM, as Ba 2+ and K + stabilized in the tunnels in advance block the intercalation/deintercalation of cations from the electrolyte. Thus, it can be inferred that for α-MnO 2 two mechanisms contribute to the charge storage. The contributions of α-MnO 2 's mechanisms are estimated. The charges based on the TSM predominantly account for 81.2–89.9% of the total charges. The charges on the SCM may contribute to 7.9–16.8% and are not negligible. The charges from double-layer capacitance may be negligible, since it is only 1.1–4.1%.

Effect of the electrolyte particularities on manganese dioxide in the neutral electrolytes containing alkaline (Li+, Na+, or K+) and alkaline-earth (Mg2+, Ca2+, or Ba2+) metal cations for electrochemical capacitor is investigated by cyclic voltammetry and electrochemical impedance spectroscopy. A very high capacitance of 357.9 F g−1 is measured when Ca2+ ion is used as electrolyte cation. The results show that cations of the electrolyte instead of proton or anions are responsible for the pseudo-capacitive behavior of manganese dioxide. The capacitance of manganese dioxide is found to depend strongly on the electrolyte particularities, for example, pH value, cation and anion species, and salt concentrations. A logarithmic dependence of capacitance of MnO2 on cation activity is obtained for all alkaline and alkaline-earth metal cations. The capacitance of MnO2 can be doubled by replacing univalent cation with bivalent cation at a close cation activity.

Posttraumatic stress disorder (PTSD) and posttraumatic growth (PTG) are two different outcomes that may occur after experiencing traumatic events. Resilience and rumination are two important factors that determine the development of these outcomes after trauma. We investigated the association between these two factors, PTSD and PTG, among Chinese survivors in an earthquake. With a convenience sample of 318 survivors from earthquake, we measured trauma exposure, PTSD, PTG, resilience, and rumination (Impact of Event Scale-Revised, Posttraumatic Growth Inventory, 10 item Connor–Davidson Resilience Scale, Ruminative Response Scale). Then we used bivariate correlation and structural equation modeling to examine the structure of relations among these factors. Results showed that resilience and reflective rumination have a positive effect on PTG (β = 0.32, p < 0.001; β = 0.17, p = 0.049). Earthquake exposure, brooding rumination and depressed-related rumination are related with higher level of PTSD (β = 0.10, p = 0.021; β = 0.33, p < 0.001; β = 0.36, p < 0.001). The findings suggest distinct determinants of the negative and positive outcomes, and this may provide better understanding about the risk and protective factors for traumatic reactions.