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Solid-state zinc ion batteries (ssBs) based on hydrogel electrolytes have received tremendous attention due to their reliable safety, high flexibility and robust performance. However, freezing of the hydrogel electrolyte and resulting low ionic conductivity limit the capability of ssBs to work at low temperatures. Herein, a wood based cellulose nanofiber (CNF)–polyacrylamide (PAM) hydrogel electrolyte was developed with a hybrid methanol/water solvent. At the optimized methanol molar ratio of 56% (Me56), the hybrid electrolyte shows a low freezing point and high-Zn2+ reversibility. The reversibility of the Zn anode is boosted in this antisolvent since Zn2+ solvation is weakened and corrosion reactions are suppressed. With the Me56 hybrid electrolyte, MgVO/Zn batteries can deliver a high specific capacity of 214 mA h g−1 after 4000 cycles at 10 A g−1 (charging time: about 1 minute). The developed CNF–PAM hydrogel maintains high flexibility under repeated bending and twisting under very cold conditions. At an extremely low temperature of −60 °C, the ssBs still deliver a high specific capacity of about 140 mA h g−1 at 10 mA g−1 while remaining flexible, exhibiting great potential to be applied in wearable devices under cold conditions.

In comparison with well-protected rigid batteries with liquid electrolytes, solid-state batteries (ssBs) are more beneficial, offering high flexibility, high wearability and leakage prevention. Currently, ssBs with the capability of bending and twisting have been extensively studied. However, it remains a challenge to develop a highly stretchable ssB with the maintenance of high performance. Herein, we report a stable solid-state zinc ion battery (ssZIB) based on a cellulose nanofiber (CNF)–polyacrylamide (PAM) hydrogel electrolyte and a Mg0.23V2O5·1.0H2O cathode. The designed CNF–PAM hydrogel shows high stretchability and robust mechanical stability. Moreover, the porous CNF–PAM hydrogel electrolyte provides efficient pathways for the transportation of zinc ions. And the robust layered structure of V2O5·1.0H2O pillared with Mg2+ ions and water supports the fast insertion/extraction of zinc ions in the lattice. Therefore, the designed ssZIB shows unprecedented high capacity at high current with durable cycling life. At a current density of 5 A g−1 (charging time of around 3 minutes), the ssZIBs can deliver a high reversible capacity of 216 mA h g−1 after 2000 cycles and retain 98.6% of the initial capacity, showing a high capacity and long-life durability at high currents. Furthermore, the designed spring ssZIBs can work under stretching with the strain reaching 650%. And the designed ssZIBs are still operational even under repeated bending, freezing, and heating conditions. The ssZIBs show robust mechanical stability, high stretchability and impressive electrochemical performance, providing a potential pathway to expand the application of ZIBs to a broad range of practical energy storage devices.

The exploration of new inexpensive rechargeable batteries with high energy-density electrodes is a key to integrate renewable sources such as solar and wind, and address sustainability issues. Herein, a facile and scalable method is developed to prepare a two-dimensional earth-abundant jarosite-KFe3(SO4)2(OH)6/rGO hybrid via a solution-phase oxidation process at elevated temperature. In this synthesis, single-layer graphene sheets serve as both structure-directing agents and growth platforms to directly grow monocrystalline KFe3(SO4)2(OH)6 nanoplates with unique hexagonal shapes, forming a KFe3(SO4)2(OH)6/rGO hybrid. As a cathode for lithium batteries, the hybrid structure exhibits a high reversible capacity of 120.5 mA h g−1 after 100 cycles at a specific current of 2C and thus retains 88% of the maximum capacity. The monocrystalline jarosite-KFe3(SO4)2(OH)6-nanoplates/rGO hybrid exhibits a discharge capacity of 143.6, 113.9, 98.2, 83.9 and 65.9 mA h g−1 at 1, 2, 5, 10, and 20C, respectively, and retains a specific capacity of 134.4 mA h g−1 when the specific current returns from 20C to 1C, displaying an excellent rate capability. At a high rate of 10C, the jarosite-KFe3(SO4)2(OH)6/rGO composites maintained 70.7 mA h g−1 after 300 cycles with a capacity retention of 78.2%, indicating remarkable cycling stability even at a high rate. Compared with KFe3(SO4)2(OH)6 particles, the KFe3(SO4)2(OH)6/rGO nanocomposites exhibit remarkably prolonged cycling life and improved rate capability. Therefore, the earth-abundant jarosite-KFe3(SO4)2(OH)6/rGO hybrid demonstrates great potential for application as a high-performance cathode material in new-generation lithium-ion rechargeable batteries.

Tin(IV) sulfide (SnS2), as a mid-band-gap semiconductor shows good potential as an excellent photocatalyst due to its low cost, wide light spectrum response and environment-friendly nature. However, to meet the demands of large-scale water treatment, a SnS2 photocatalyst with a red-shifted band gap, increased surface area and accelerated molecule and ion diffusion is required. Doping is a facile method to manipulate the optical and chemical properties of semiconductor materials simultaneously. In this work, SnS2 photocatalysts with varied Ag doping content are synthesized through a facile one-step hydrothermal method. The product is characterized by XRD, SEM, TEM and UV-Vis spectrometry. The photocatalytic activity of the as-prepared Sn1−xAgxS2 is studied by the degradation of methylene blue (MB) dye under solar light irradiation. It is found that increasing the Ag dopant concentration can effectively increase the solar light adsorption efficiency of the photocatalyst and accelerate heterogeneous photocatalysis. The optimal concentration of Ag dopant is found to be 5% with the highest rate constant being 1.8251 hour−1. This study demonstrates that an optimal amount of Ag doping can effectively increase the photocatalytic performance of SnS2 and will promote the commercialization of such photocatalysts in the photocatalytic degradation of organic compounds.

Tin disulfide (SnS2) has been considered as a prospective counter electrode (CE) material for dye-sensitized solar cells due to its good electrocatalytic properties. However, its low electronic and ionic conductivities pose challenges for using it in high-performance dye-sensitized solar cells (DSSCs). Herein, doping is utilized to improve the properties of SnS2 for application as a DSSC counter electrode. Ag-doped SnS2 samples with various doping amounts are prepared via a facile one-step solvothermal route. It is found that the DSSC based on a 5% Ag-doped SnS2 CE demonstrates the best performance showing an impressive photovoltaic conversion efficiency (PCE) of 8.70% which exceeds the efficiency of a Pt-based DSSC (7.88%) by 10.41%, while the DSSC consisting of undoped SnS2 only exhibits a PCE of 6.47%. Such an enhanced efficiency of the DSSC is attributed to the effectively improved electrocatalytic activity and mixed conductivity resulting from the Ag dopant. Therefore, the Ag-doped SnS2 CE proves to be a promising alternative to the expensive Pt CE in DSSCs and may pave a new way for large-scale production of new-generation DSSCs.

Complex heterostructured nanomaterials receive tremendous attention due to their superior physical and chemical performances than single-structured materials. Nevertheless, it remains a great challenge to precisely control the composition (crystalline or amorphous), size and dimension of the building blocks of hierarchical nanostructures. Herein, we report a scalable method for fabricating crystalline–Co3O4–carbon@amorphous-FeOOH interwoven hollow polyhedrons through thermal treatment paired with solution-phase growth for application as anodes in new-generation lithium ion batteries. In this synthesis, well-defined Co3O4–carbon hollow polyhedrons serve as both oxidizing agent and growth platform for amorphous FeOOH nanowires. The obtained heterostructured hollow polyhedrons exhibit a high reversible capacity of 603 mA h g−1 after 100 cycles at the specific current of 200 mA g−1, showing a capacity fading of only 0.158% per cycle between 10 to 100 cycles, much lower than that of pure Co3O4–carbon hollow polyhedrons (0.604%). When the specific current returns from 2000 mA g−1 to 50 mA g−1, Co3O4–carbon@FeOOH heterostructure maintains a specific capacity of 1120 mA h g−1, demonstrating remarkable cycleability and high rate capability. Such superior performance is attributed to the synergistic effect of integrated crystal and amorphous components as well as the unique interwoven heterostructure. The design of such an interwoven 3D frame architecture provides a new opportunity for obtaining high-performance electrode materials in the field of energy storage.

We report, for the first time, a simple and novel synthesis of a Li-rich layered-spinel core-shell heterostructure (L@S core-shell) via evaporation-induced self-assembly (EISA) of Ni-doped Li4Mn5O12 nanoparticles (Li4Mn4.5Ni0.5O12) onto the surface of layered Li[Li0.2Mn0.54Ni0.13Co0.13]O2 (LMNCO) without using any surfactant during the coating process. The resultant L@S core-shell as a cathode in lithium ion batteries demonstrates significantly improved specific capacity, cycling performance and rate capability compared to pristine LMNCO.

To combine the merits of the one-dimensional structure and the porous structure, mesoporous VO2 nanowires have been designed and reported for the first time. Excellent cycling stability and enhanced rate performance are obtained and may be attributed to the mesoporous nanowires, realizing both high surface area for more active sites and facile stress relaxation resulting in excellent structure stability. Our results demonstrate that the mesoporous nanowires are favourable for high-rate and long-life lithium batteries.