Search

Perovskite solar cells (PSCs) have achieved a huge success in power conversion efficiency (PCE), although they still suffer from the long-term stability problem caused by the intrinsic sensitivity ...

The design of highly active, stable, and low-cost oxygen reduction reaction (ORR) electrocatalysts to replace platinum-based materials is crucial to the development of renewable energy technologies. Herein, novel 3D edge-enriched Fe3 C@C nanocrystals with a core-shell structure grown on reduced graphene oxide (rGO) networks (Fe3 C@C/rGO) are reported as highly efficient and stable electrocatalysts for the ORR. The rGO nanosheets act as a host and provide vital support for local growth of edge-enriched Fe3 C@C nanocrystals, leading to a large surface area of 263 m2 g-1 and superstable hybrid structure. The unique structural design of the Fe3 C@C/rGO hybrid enables fast mass transport and a substantial number of exposed active edge sites for electrocatalytic reaction. The Fe3 C@C/rGO hybrid exhibits excellent ORR catalytic activity, with a high positive onset potential close to 1.0 V, a Tafel slope of 65 mV dec-1 , and excellent durability with only about 8 % current density decay at 0.8 V after 20 000 s continuous operation, which is superior to that of commercial Pt/C catalyst in an alkaline electrolyte.

This study presents a comprehensive life cycle assessment (LCA) on a potential next-generation lithium ion battery (LIB) with molybdenum disulfide (MoS2) anode and Nickel-Cobalt-Manganese oxide (NMC) cathode. The NMC-MoS2 battery is configured with 49.4 kWh capacity enabling a 320 km driving range for a mid-sized EV. In this study, the MoS2 anode synthesis is modeled based on our lab-scale experimentation and the battery design is based on the electrochemical parameters obtained from our lab results. The life cycle impact assessment is conducted using the ReCiPe method. The freshwater ecotoxicity impact is assessed through the modified USEtox™ method, based on the characterization factor of the CNT (carbon nanotubes) is derived. The obtained impact results of the NMC-MoS2 battery are benchmarked with those of a conventional NMC-Graphite battery under the same driving distance per charge. The results show that the NMC-MoS2 battery has higher environmental impacts in most impact categories compared to a conventional NMC-Graphite battery. Impacts on global warming potential and fossil depletion potential are 6%–7% higher while impacts in freshwater ecotoxicity, freshwater eutrophication, human toxicity, marine toxicity, marine eutrophication and terrestrial ecotoxicity are 141%–271% higher. Finally, a sensitivity analysis is performed to investigate the robustness and reliability of the LCA results.

Although lithium-sulfur (Li-S) batteries have attracted much attention due to their high theoretical specific energy and low cost, their practical applications have been severely hindered by poor cycle life, inadequate sulfur utilization, and the insulating nature of sulfur. Here, we report a rationally designed Li-S cathode with a dual-confined configuration formed by confining sulfur in 2D carbon nanosheets with an abundant porous structure followed by 3D graphene aerogel wrapping. The porous carbon nanosheets act as the sulfur host and suppress the diffusion of polysulfide, while the graphene conductive networks anchor the sulfur-adsorbed carbon nanosheets, providing pathways for rapid electron/ion transport and preventing polysulfide dissolution. As a result, the hybrid electrode exhibits superior electrochemical performance, including a large reversible capacity of 1328 mA h g(-1) in the first cycle, excellent cycling stability (maintaining a reversible capacity of 647 mA h g(-1) at 0.2 C after 300 cycles) with nearly 100% Coulombic efficiency, and a high rate capability of 512 mA h g(-1) at 8 C for 30 cycles, which is among the best reported rate capabilities.

Flexible solar cells have attracted increasingly attentions due to its possible extensive applications in wearable, portable, flyable and deployable devices. The fabrication of flexible perovskite solar cells (PSCs) strictly requires the fabrication temperature below 150 °C due to the limitation of flexible substrate. For retaining the process at low temperature, applying anti-solvents has becoming to the most popular method. However, the involvement of anti-solvents requires very precise control and brings toxicity in the fabrication procedures, which limits its large-scale industrial use. Here, we propose a strategy that simply replacing the usual anti-solvents with CH3NH3Br (CH3NH3+, MA) into dynamic spinning of perovskite precursor significantly reduces the formation energy of α-phase FA-perovskites to 40 °C. An optimized annealing temperature at 100 °C provides high-quality morphology and crystallization of FA-based perovskite films with superior optoelectric properties, yielding a power conversion efficiency (PCE) of flexible PSCs to 18.5% and retaining over 80% of its initial PCE after 1200 bending cycles. This is the best performance so far of preparing anti-solvent free flexible PSCs at low temperature (≤100 °C). Our results offer new insights into producing high-quality FA-based perovskite materials at low temperature, which paves the way for further development of flexible PSCs to industrial commercialization.

A three-dimensionally interconnected carbon nanotube/layered MoS2 nanohybrid network is reported with best-so-far rate capability and outstanding long cycle life as lithium ion battery anode. The monolayer and bilayer MoS2 ultrathin nanosheets with large surface to volume ratio facilitate fast Li ion transport further boosting high power capability, while incorporating high conductive CNT enhances the electronic conductivity and retains the structural integrity. The nanohybrid delivers discharge capacity as high as 512 mAh g−1 at 100 A g−1 and 1679 mAh g−1 over 425 cycles at 1 A g−1 with 96% discharge capacity retention of the initial cycle.

A multilayered structural silicon-reduced graphene oxide electrode with superior electrochemical performance was synthesized from bulk Si particles through inexpensive electroless etching and graphene self-encapsulating approach. The prepared composite electrode presents a stable charge-discharge performance with high rate, showing a reversible capacity of 2787 mAh g(-1) at a charging rate of 100 mA g(-1), and a stable capacity over 1000 mAh g(-1) was retained at 1 A g(-1) after 50 cycles with a high columbic efficiency of 99% during the whole cycling process. This superior performance can be attributed to its novel multilayered structure with porous Si particles encapsulated, which can effectively accommodate the large volume change during the lithiation process and provide increased electrical conductivity. This facile low-cost approach offers a promising route to develop an optimized carbon encapsulated Si electrode for future industrial applications.

SnS2 nanoparticles and SnS2 nanoflake/CNTs composite are prepared by a low-cost facile hydrothermal method for their use in rechargeable Li-ion batteries. It is found that the presence of multi-walled CNTs during synthesis greatly affects the morphology of as-formed SnS2 nanostructures, and circinal single-layer and multilayer SnS2 nanoflakes enwrapped by CNTs are produced. The composite is further oxidized to porous SnO2 nanoflake/CNTs hybrid by annealing at 500 °C in air. The formation mechanism of SnS2/CNTs and SnO2/CNTs composites is examined. All the three materials are used as the anode in Li-ion batteries. The SnS2/CNTs composite delivers stronger cycling stability than the pure SnS2 anode. In tests the former exhibits excellent capacity retention of 91.5% at 100 mA g−1 over 50 cycles, while the latter displays 66.8%. The rate capability of SnS2/CNTs composite is much better than pure SnS2 as well. Redox reaction characteristics and Li-ion transfer kinetics at the two SnS2 anodes are studied by differential capacity plots and electrochemical impedance spectroscopy. It is discovered that the SnS2/CNTs composite with larger surface area allows faster Li-ion transfer kinetics, effective cushion of volume changes, and thus gains the improved Li-ion intercalation behaviours. The capacity of the tin-based anode can be further raised by transformation to a SnO2/CNTs hybrid that also delivers excellent rate and cycling performances.

Microbial electrolysis cells (MECs) can produce hydrogen gas from organic compounds in an energy-efficient way by taking advantage of the potential generated by microorganisms. However, hydrogen evolution reaction (HER) in MECs is slow and thus requires catalysts. A challenge for MEC development therefore lies in the development of cost-effective HER catalysts. In this study, a nanocomposite with molybdenum disulfide (MoS2) coated on highly conductive carbon nanotubes (CNTs) was synthesized as an alternative HER catalyst, and examined in an MEC for hydrogen production. Linear sweep voltammogram experiments demonstrated enhanced HER activity with increasing CNT content. The results suggest that conductivity may be the main limiting factor for overall HER catalysis by MoS2. MEC tests showed that MoS2/CNT-90 achieved hydrogen production that was comparable to the Pt-based catalyst. The low cost of the MoS2 composites will make it competitive as an effective HER catalyst for future MEC applications.

Temperature monitoring is important for improving the safety and performance of Lithium Ion Batteries (LIB). This paper presents the feasibility study to insert flexible polymer embedded thin film thermocouples (TFTCs) in a lithium ion battery pouch cell for in-situ temperature monitoring. A technique to fabricate polyimide embedded TFTC sensors on glass substrates and later transfer it onto thin copper foils is presented. The sensor transfer process can be easily integrated into the assembly process of a pouch cell, thus holding promise in implementing in Battery Management Systems (BMS). Internal temperature of the LIB pouch cell was measured in-situ when the sensor embedded battery was operated at high rate charge–discharge cycles. The polyimide embedded TFTCs survived the battery assembly process and the battery electrolyte environment. It is observed that the heat generation inside the battery is dominant during the high-rate of discharges. The developed technique can serve to improve the battery safety and performance when implemented in battery management systems and enhance the understanding of heat generation and its effects.

Sulfur nanoparticles wrapped with a conductive graphene framework was synthesized with a high sulfur loading through a scalable one-step process. The graphene-coated sulfur nanostructured composite, when used as cathode for lithium sulfur battery, shows a reversible capacity of 808 mAh g(-1) at a rate of 210 mA g(-1) and an average columbic efficiency of ∼98.3% over 100 cycles. It is found that graphene oxide (GO) with a porous structure offers flexible confinement function that helps prevent the loss of active materials, thus extending the cycling life of the electrode. Moreover, reduced graphene oxide provides a conductive network surrounding the sulfur particles, which facilitates both electron transport and ion transportation. This novel one-step, all-solution-based process is scalable and provides a promising approach for potential industrial applications.

Band gap opening and modulating are critical in dictating the functionalities of single walled carbon nanotubes (SWCNTs) in a broad array of nano-devices. Using first-principles density functional theory calculations, a class of semiconducting armchair SWCNTs with a distinctive BN line defect are studied, showing a super capacity to open the band gap of (4, 4) SWCNT to as large as 0.86 eV, while the opened band gap are found decreasing with the increasing diameters of SWCNTs. The opened band gap of SWCNTs can also be successfully modulated through both mechanical and electrical approaches by applying compressive uniaxial strain and electric field. This study provides novel insights into the large band gap opening and modulating of SWCNTs and could be useful in facilitating future applications of SWCNTs in electronic, optical and thermoelectric devices.