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Sulfide-based solid electrolyte is one of the most promising solid electrolytes due to its high ionic conductivity and wide electrochemical window. However, it suffers from serious interfacial issues with lithium metal, which hinder the lithium-ion transport during cycling process and increase the interfacial resistance and instability. Protection only from Li anode side is not enough since Li enters into the bulk solid electrolyte resulting reaction and dendrite growth. Herein, we design a graphene oxide (GO) coated solid electrolyte Li7P3S11 particles for stable and efficient all-solid-state battery application. The GO could partially isolate the Li7P3S11 solid electrolyte from lithium metal. Meanwhile, the GO or rGO reduced by Li guide the homogeneous growth of Li and increase the cycling stability. Our work provides a facile method to fully protect Li7P3S11 in three directions from reaction with Li metal for dendrite-free and highly stable sulfide-based all-solid-state battery applications. This work might inspire the community with new material engineering/design strategies toward practical application in highly stable all solid state lithium-ion batteries.

Rechargeable Li-O2 batteries (LOBs) have been receiving intensive attention because of their ultra-high theoretical energy density close to the gasoline. Herein, Ag modified urchin-like α-MnO2 (Ag-MnO2) material with hierarchical porous structure is obtained by a facile one-step hydrothermal method. Ag-MnO2 possesses thick nanowires and presents hierarchical porous structure of mesopores and macropores. The unique structure can expose more active sites, and provide continuous pathways for O2 and discharge products as well. The doping of Ag leads to the change of electronic distribution in a-MnO2 (i.e., more oxygen vacancies), which play important roles in improving their intrinsic catalytic activity and conductivity. As a result, LOBs with Ag-MnO2 catalysts exhibit lower overpotential, higher discharge specific capacity and much better cycle stability compared to pure α-MnO2. LOBs with Ag-MnO2 catalysts exhibit a superior discharge specific capacity of 13,131 mAhg−1 at a current density of 200 mAg−1, a good cycle stability of 500 cycles at the capacity of 500 mAhg−1. When current density is increased to 400 mAg−1, LOBs still retain a long lifespan of 170 cycles at a limited capacity of 1,000 mAhg−1.

High ionic conductivity and superior interfacial stability of solid electrolytes at the electrodes are crucial factors for high-performance all-solid-state sodium batteries. Herein, a composite solid electrolyte Na3PS4-polyethylene oxide is synthesized by the solution-phase reaction method with an improved ionic conductivity up to 9.4 × 10−5 S/cm at room temperature. Moreover, polyethylene oxide polymer layer is wrapped homogeneously on the surface of Na3PS4 particles, which could effectively avoid the direct contact between Na3PS4 electrolyte and sodium metal, thus alleviate their side reactions. We demonstrate that all-solid-state battery SnS2/Na with the composite solid electrolyte Na3PS4-polyethylene oxide delivers an enhanced electrochemical performance with 230 mAh/g after 40 cycles.

As high energy density and enhanced safety are required for the lithium-ion battery development, all-solid-state battery has attracted significant attention. Herein, we report an all-solid-state full battery consisting of a Li7P3S11 solid electrolyte coated silicon anode, Li2S/graphene composite cathode, and Li7P3S11 solid-state electrolyte. With a high capacity for the silicon anode and Li2S cathode, this battery yields a high theoretical specific energy density up to 1495 Wh kg−1, which is higher than that of lithium-ion batteries based on oxide cathodes. Moreover, Li2S cathode is used as lithium source instead of using metallic lithium, avoiding interface reaction between lithium metal anode and sulfide electrolyte Li7P3S11. This all-solid-state battery system we proposed could avoid the safety issues associated with the use of lithium metal and be a promising candidate for an enhanced energy density, which would promote their applications in the fields of electric vehicles and portable electronics.

The biotoxicity and environmental applications of carbon nanomaterials have always been the focus of research. In this research, functional carbon nanodots (FCNs) show high promotion effects on regulating the growth, development and yield of tomato under drought stress, due to their up-regulation effects on the physiological processes of plants including photosynthesis, antioxidant system, osmotic adjustment, as well as soil amelioration in physicochemical properties and microbial environment during vegetative and reproductive growth stage. The reduction of tissue water content and water use efficiency are moderated by FCNs through improving root vigor and osmolytes (soluble sugar and proline) level, which contributes to maintain the enzyme function, photosynthesis and nutrient uptake in plant. FCNs regulate the enzymatic and non-enzymatic antioxidant system to scavenge reactive oxygen species (ROS) and inhibit the lipid peroxidation, thus protect the membrane structure and function of plant cells under stress. FCNs up-regulate soil microbial communities under drought stress by regulating the soil pH, enzyme activity, organic carbon and organic matters contents. Our results prove that FCNs are biological friendly to plant growth and soil environment under drought stress, thus exhibit potential as emendator to promote plant tolerance and improve agricultural productivity in water-deficient areas.

Low ionic conductivity and poor interfacial compatibility between lithium electrodes and Li7P3S11 sulfide solid electrolytes are the greatest challenges for all-solid state lithium-sulfur batteries. Herein, we introduce a hybrid solid electrolyte with Li7P3S11 being wrapped with polyethylene oxide-LiClO4 (PEO-LiClO4). As served as conductive bridge between Li7P3S11 particles, PEO-LiClO4 would provide Li+ transition paths between Li7P3S11 particles, thus successfully improve its ionic conductivity. Moreover, the polymer layer of PEO-LiClO4 can isolate lithium metal and Li7P3S11 solid electrolyte, suppressing the reaction between lithium electrode and Li7P3S11 electrolyte. Therefore, hybrid solid electrolyte Li7P3S11-PEO-LiClO4 shows excellent interfacial compatibility with lithium foil. Lithium-sulfur battery with the hybrid electrolyte Li7P3S11-PEO-LiClO4 exhibits much improved electrochemical performance with better cycling stability and higher Coulombic efficiency.

To solve the critical issues like high polarization and unstable cycle ability, it is vital to design low-cost, stable and efficient catalytic cathode material for nonaqueous Li-O2 batteries (LOBs). Herein, a hollow urchin-like hollandite Ag2Mn8O16 electrocatalyst is fabricated by one-step hydrothermal method. The mixed bimetallic oxide with diverse valences (Mn3+ and Mn4+) and active oxygen defects provide sufficient active sites, and Ag Mn O bonds accelerate charge transformation. LOBs with the well-designed porous Ag2Mn8O16 cathode show superior electrochemical performances in LOBs, including ultrahigh specific capacity (7912 mAh gc−1 at 100 mA gc−1), good rate performance (5076 mAh gc−1 at 250 mA gc−1, 64.16%) and long-term cycle stability (320 cycles at 100 mA gc−1 within a limited capacity of 250 mAh gc−1 and 133 cycles at 200 mA gc−1 within a limited capacity of 500 mAh gc−1). This work provides a positive effect on designing better catalytic cathode materials for LOBs and push forward the commercialization progress.

Functional carbon nanodots (FCNs) with multiple chemical groups have great impact on the growth regulation of plants. To understand the role of the chemical groups, FCNs were reduced from the raw material by pyrolysis method and hydrolysis method. The chemical structure of these materials were characterized by using TGA, TEM, FT-IR, XPS, Raman and elementary analysis. The raw and reduced FCNs were used as plants growth regulators in culture medium of Arabidopsis thaliana. Our results indicate there is a strong correlation between the physiological responses of plants and the surface chemistries (especially carboxyl group and ester group) of the nanomaterials. The quantum-sized FCNs with multiple carboxyl groups and ester groups show better aqueous dispersity and can induce various positive physiological responses in Arabidopsis thaliana seedlings compared with the FCNs decorated without carboxyl and ester as well as aggregated FCNs. The raw FCNs present higher promotion capacity in plants biomass and roots length, and the quantum-sized FCNs are easier to be absorbed by plants and generate more positive effects on plants.

Methanol gas sensors with excellent performances are in great demand to monitor the industrial manufacture and many household products. We have synthesized Pt-activated SnO2 nanoparticles partly wrapped by reduced graphene oxide (RGO) for high performance methanol gas sensor application. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) results indicated that the platinum element is present in two types, including metal (Pt) and tetravalent metal oxide (PtO2) in the Pt-activated SnO2 clusters. The SnO2 nanoparticles with an average size of about 10 nm are in form of cluster type and there are abundant random wormhole-like pores throughout each cluster. The gas responses of the pristine SnO2 gas sensor, Pt-activated SnO2 gas sensor and the RGO-assisted sensors toward 40 ppm methanol at the relatively low operating temperatures (110 °C) were 7.8, 38.5 and 60.1, respectively. And the sensor exhibited shorter response time with only 6 s. The excellent gas-sensing properties are mainly attributed to the improved electronic interaction and the reduced potential barrier between RGO and Pt/SnO2.

Phytoremediation is one of the effective, economic and green approaches to cope with the increasing worldwide heavy metal (HM) pollution. Here, we evaluate the effects of functional carbon nanodots (FCNs) against the hyperaccumulation capacity as well as the physiological and genetic responses of water hyacinth under Pb2+ or/and Cd2+ stress. The bioaccumulation efficiency, HM content and transfer factor, biomass, root development, chlorophyll content, antioxidant system and genes expression are investigated at various concentration of HMs. Based on the excellent adsorption capacity and plant growth regulation ability, FCNs and nitrogen doped FCNs (N-FCNs) cooperate with water hyacinth to improve their HMs removal efficiencies. FCNs and N-FCNs immobilize excess HMs ions in plant, smartly regulate enzymatic levels to mitigate oxidative damage, as well as regulate the microelement uptake and related gene expression, thus improve plant tolerance against HMs stress. Although Pb and Cd have antagonistic effects on bioaccumulation of water hyacinth to the single metal, FCNs and N-FCNs can cooperate with water hyacinth to raise the removal efficiency of HMs in water, and enhance plant tolerance under Pb-Cd combined stress. The promotion effects of FCNs and N-FCNs on phytoremediation are more effective than conventional carbon nanomaterials, including carbon nanotubes and graphene oxides. These findings demonstrate that the application of FCNs or N-FCNs can improve the phytoremediation efficiency in the restoration of HMs contaminated water area. This study provides important insights into the possibility of using FCNs-based nanomaterials and water hyacinth as synergistic system for remediation of Cd-Pb contaminated water area.

With high specific capacity, the layered Li-rich Mn-based oxide (LRMO) is a promising candidate cathode material for Li-ion batteries. However, the irreversible release of Li-ions during the first charging process, instability of LRMO/electrolyte interface and relatively low ion conductivity of LRMO result in low initial Coulombic efficiency (ICE), poor cycle stability and rate performance, which prohibit its further application. Interface engineering via additive coating is expected to effectively address these issues. Herein, we rely on potassium Prussian blue (KPB), a Li+ acceptor with good ion conductivity, as a new coating material on LRMO particles. The KPB coating not only forms a protective layer on the surface of LRMO against electrolyte corrosion, but also functions as a host for Li+ transport and accommodation, leading to enhanced ion conductivity and ICE of LRMO cathode. Consequently, 2 wt% KPB coated LRMO cathode achieved an initial discharge capacity of up to 281.7 mA h g−1 with an ICE of 85.69% compared to an ICE of 79.52% for the LRMO cathode without coating. The cycling and rate performance are also greatly improved as evidenced by the well maintained capacity of up to 176.8 mA h g−1 after 100 cycles at a current density of 0.5 C, compared to the limited capacity of only 135.3 mA h g−1 for the LRMO cathode without coating. This work pioneers the use of potassium Prussian blue as additive coating material to enhance performance of LRMO cathode, and we expect it to inspire the battery community with new strategies of material engineering/design toward practical application in high-energy lithium-ion batteries.

Polyethylene-oxide (PEO)-based electrolyte is one of the most promising solid electrolytes due to its outstanding safety and excellent flexibility. However, the most common method to fabricate PEO-based electrolyte is casting, which requires intensive use of toxic organic solvent. Besides, the agglomeration of filler in the composite electrolyte fabricated by casting limits further enhancement of ionic conductivity. In this work, we provide a facile solvent-free cold-pressing method to prepare well-dispersed LAGP @ PEO composite solid-state electrolyte. The ionic conductivity of LAGP @ PEO composite electrolyte can reach about 4.4 × 10−5 S cm−1 at room temperature which is nearly one order of magnitude higher than that of the casting one (3.3 × 10−6 S cm−1). The integrated all-solid-state batteries display excellent cycling stability and good rate performance at 50 °C. Our work provides a facile solvent-free cold-pressing method to fabricate polymer-based composite electrolyte with well-dispersed filler for all-solid-state batteries.