2D TaSe2 as a zero-strain and high-performance anode material for Li+ storage

The zero-strain property of anode materials plays a determining role in their safety and cycling performance. However, the zero-strain anode materials currently developed are very limited and show significant performance trade-offs. Herein, novel highly conductive two-dimensional (2D) TaSe₂ is first explored as an anode material. Due to the reaction mechanism of Li⁺ solid-solution, the 2D TaSe₂ anode shows the zero-strain feature (0.042%) at full lithiation, resulting in excellent cycling stability. Owing to the dual active sites (Ta and Se atoms) and the double-sided Li⁺ storage mechanism, the 2D TaSe₂ anode exhibits the highest specific capacity of zero-strain anode materials, and it is the only zero-strain anode material that exceeds the graphite anode in energy density. Additionally, because of its remarkable Li⁺/electronic conductivity and high mass density, the anode is insensitive to the loading mass (3.78-12.66 mg cm^-2), resulting in high areal (9.94 mA h cm^-2), volumetric (∼5 times greater than the graphite anode), and gravimetric specific capacities (the only zero-strain anode higher than the graphite anode). When matched with the high-loading LiFePO₄ cathode (11.4 mg cm^-2), the full cell also presents overall good performance. Experiment results combined with density functional theory (DFT) calculations are adopted together to reveal the mechanisms of Li⁺ storage and transfer. This work provides a good paradigm to design zero-strain and high-performance alkali-metal-ion anode materials.

Hybrid Carbon Sphere Chain-MnO2 Nanorods as Bifunctional Oxygen Electrocatalysts for Rechargeable Zinc-Air Batteries

It is now recognized that the development of self-supported and efficient bifunctional air cathodes via the direct growth of earth-abundant catalysts onto the surface of the conductive collector would be a cutting-edge strategy to reduce interfacial resistance, enhance the mechanical tenure, and reduce the final weight and cost of manufacturing of rechargeable Zn-air batteries (ZABs). This work reports an innovative self-supported precious metal-free electrode, comprising carbon sphere chains (CSCs) directly grown onto a carbon paper (CP) substrate, wherein the CSCs have a functionalized surface bearing carbon nanobud defects, oxygen functional groups, and high-density MnO₂ hierarchical nanorods (NRs), uniformly coating the surface of CSCs. Not only is the metal-free functionalized CSC catalyst functional for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) but its combination with MnO₂ NRs impressively enhances the ORR/OER activities. A homemade ZAB assembled with functionalized CSC/MnO₂ air cathode can successfully power a timer for a period of 17 days with no voltage loss, whereas two series-connected ZABs can light up 39 red light-emitting diode (LED) bulbs. The self-supported and earth-abundant-based CSC/MnO₂ materials open up an opportunity for lightweight and cost-effective ZABs and metal-air batteries in general.

Polymer fiber membrane-based direct ethanol fuel cell with Ni-doped SnO2 promoted Pd/C catalyst

The PFM-based DEFC with as-prepared Pd/Ni–SnO₂/C as the anode catalyst and porous NiCo₂O₄ as the cathode catalyst delivers encouraging properties.