Electrode-electrolyte interactions dictate thermal stability of sodium-ion batteries

This work delineates the thermal safety of full-scale sodium-ion batteries (SIBs) by interrogating the material-level electrochemical and thermal responses of micro and nano-structured tin (Sn) based anodes and sodium vanadium phosphate (NVP) cathodes in suitable electrolyte systems. Informed by these material-level signatures, we delineate cell-level thermal safety maps cognizant of underlying electrode-electrolyte interactions in SIBs.

Approaches for electroplating sludge treatment and disposal technology: Reduction, pretreatment and reuse

Electroplating sludge (ES) has become an obstacle to the sustainable development of the electroplating industry. Electroplating sludge has a large storage capacity, with a high concentration of soluble pollutants (heavy metals), which has great potential to harm the local ecosystems and human health. Although much research has been done in this area, there seems to be no mature and stable solution. Therefore, the latest technologies for the reduction, pretreatment and reuse of electroplating sludge are emphatically introduced based on the analysis of the characteristics of electroplating sludge and its impact on the ecological environment. The factors hindering the treatment and disposal of electroplating sludge are pointed out, and reasonable and feasible suggestions to solve this problem are proposed. The solidification and removal mechanism of heavy metals in electroplating sludge is emphatically analyzed. The physicochemical and separation processes of heavy metals, as well as thermal treatment technique are discussed. Finally, it is proposed to establish a database of the physicochemical properties and elemental content of electroplating sludge to achieve its systematic treatment and digestion. We hope that this paper can help solve the problem of electroplating sludge and promote the sustainable development of the electroplating industry.

Double-Enhanced Core-Shell-Shell Sb2S3/Sb@TiO2@C Nanorod Composites for Lithium- and Sodium-Ion Batteries

For most alloying- and conversion-type anode materials, a huge volume expansion and structure degradation of the electrodes always hinder their applications. In this work, a novel core-shell-shell Sb2S3/Sb@TiO2@C nanorod composite has been designed layer by layer, which includes an inner Sb2S3/Sb heterostructure core protected by an oxygen-deficient TiO2 shell and a conductive carbon shell. It is interesting to observe that, during the carbothermic reduction process, the previous Sb2S3 nanorod cores are partially reduced into a metallic Sb phase and the reduced TiO2 also creates many oxygen vacancies, which can greatly enhance the conductivity of the semiconductor Sb2S3. Thanks to the double effects of the TiO2 middle shell and carbon outer shell, the unique double-shelled structure design creates an enhanced dual protection, which can better accommodate the volume-expansive deformation and preserve the structural integrity of the active Sb2S3/Sb core. Especially, the TiO2 middle layer is self-assembled by numerous nanoparticles acting as a nanopillar backbone, which supports between the nanorod core and outer carbon shell to better buffer the volume changes. As a result, the core-shell-shell Sb2S3/Sb@TiO2@C anode shows lithium and sodium storage performances superior to those of the pristine Sb2S3 and core-shell Sb2S3@TiO2 electrodes. For lithium-ion batteries, the Sb2S3/Sb@TiO2@C nanorod composite achieves an initial discharge/recharge capacity of 1244.9/1005.1 mAh g-1 with an initial Coulombic efficiency of about 80.7%, an enhanced rate capability with a capacity of 593.2 mA h g-1 at 5.0 A g-1, and prolonged cycling life for 500 cycles with a reversible capacity of 495.8 mAh g-1 at 0.5 A g-1. For sodium-ion batteries, the nanorodalso exhibits an improved performance with an initial discharge/recharge capacity of 781.4/574.0 mAh g-1 (initial Coulombic efficiency of about 73.46%) and cycling for 400 cycles with a reversible capacity of 422.6 mAh g-1 at 0.8 A g-1. This research sheds light upon double-shell structure designs with an effective middle shell to enhance the energy storage performance of electrode materials.

Ball milling transformed electroplating sludges with different components to spinels for stable electrocatalytic ammonia production under ambient conditions

Electroplating sludge is classified as hazardous waste, but it is also a potential raw resource since it contains plenty of transition metals. However, the component of electroplating sludge is unstable, which hinders recycling. This work investigates the possibility to synthesize spinels with stable catalytic performances by different electroplating sludges. The obtained catalysts are used in electrocatalytic N₂ reduction to produce ammonia. As a result, CuCr₂O₄, ZnCr₂O₄, and NiCr₂O₄ spinels are successfully synthesized by a ball-milling and calcination method. These spinels result in ammonia yields of 7.30-8.86 μg h^-1 mg^-1_cat. Among the three spinels, CuCr₂O₄ shows the highest yield of 8.86 μg h^-1 mg^-1_cat at -0.9 V. Its faradaic efficiency reaches 0.57%. In addition, no by-product N₂H₄ is detected, indicating a high selectivity. The catalytic process is carried out by both distal and alternating pathways, in which metal doping and oxygen vacancy function as binding sites for N₂ adsorption and reduction. Above results indicate that electroplating sludges with unstable components are feasible to produce spinels for stable electrocatalytic ammonia production under ambient temperature. This is in favor of high-value-added utilization of hazardous waste, and devotes to circular economy.

Sandwich shelled TiO2@Co3O4@Co3O4/C hollow spheres as anode materials for lithium ion batteries

A sandwich shelled hollow TiO₂@Co₃O₄@Co₃O₄/C composite is synthesized by consecutive coating of Co₃O₄ nanosheets and TiO₂ particles on Co₃O₄/C hollow spheres. The composite delivers an excellent lithium storage performance, maintaining 1081.78 mA h g^-1 after 100 cycles at 0.2 A g^-1 and 772.23 mA h g^-1 after 300 cycles at 1 A g^-1, due to its superior structure combining the advantages of each component with favorable electron-transfer, Li⁺-diffusion properties, and distinguished stability.

Facile synthesis of uniform N-doped carbon-coated TiO2 hollow spheres with enhanced lithium storage performance

Great efforts, such as nano-structuring and carbon coating, have been devoted to addressing the poor rate performance of TiO2 anodes in lithium ion batteries, which is mainly caused by sluggish Li ion diffusion and poor electrical conductivity of the bulk material. However, the complicated fabrication processes make most of these strategies much low practical significance. Herein, a scalable and facile strategy based on sacrificial template-accelerated hydrolysis and polydopamine coating is proposed to manufacture uniform N-doped carbon-coated TiO2 hollow spheres. The nanostructured hollow structure can shorten the path of Li+ insertion/extraction in the electrode material. More importantly, the uniform carbon layer can improve the electronic conductivity of TiO2 during long-term cycling. Thus, a reversible capacity can be obtained of as high as 390.2 mA h g-1 at a current density of 0.1 A g-1. Furthermore, a high capacity of 166.3 mA h g-1 after 2000 cycles at 5.0 A g-1 shows that the carbon-coated TiO2 hollow spheres deliver good capacity retention and cycling performance.

Polymerization inspired synthesis of MnO@carbon nanowires with long cycling stability for lithium ion battery anodes: growth mechanism and electrochemical performance

Manganese-based transition metal oxides are regarded as one kind of high capacity and low cost anode material for Li-ion batteries. To overcome the challenges of poor electrical conductivity and large volumetric expansion during the charging-discharging process of MnO, we here synthesize MnO@carbon (MnO@C) nanowires via the polymerization inspired in situ growth of [Mn-NTA] (NTA = nitrilotriacetic acid) precursor nanowires with a subsequent heat treatment process. The growth mechanism of [Mn-NTA] precursor nanowires was studied. The morphology of the precursor nanowires depended largely on the molar ratio of MnCl2 to NTA reactants. At a molar ratio of 2, the length of the [Mn-NTA] nanowires reached up to more than 140 μm. Furthermore, the as-synthesized MnO@C nanowires were integrated with a very low content of reduced graphene oxide (rGO) to prepare a self-standing paper-like MnO@C/rGO anode for lithium ion batteries without a binder. The MnO@C/rGO anode showed a unique structure with one-dimensional porous MnO nanowires hierarchically encapsulated by a conductive carbon framework. As a result, the self-standing electrode achieved a high capacity of 1368 mA h g-1 after 100 cycles at a current density of 100 mA g-1 and prominent cycling stability with a capacity of 689.9 mA h g-1 even after 1700 cycles at 2000 mA g-1.