L'Occident / [directeur : Adrien Mithouard] ; [secrétaire de la rédaction : Albert Chapon]

janvier 19131913/01 (T21,N122)-1913/06 (T21,N127)

Figure S2 from Amorphous mesoporous GeO<i>_x</i> anode for Na-ion batteries with high capacity and long lifespan

XRD pattern of the annealed GeOx sample

Hydrogenated TiO₂ Branches Coated Mn₃O₄ Nanorods as an Advanced Anode Material for Lithium Ion Batteries

Rational design and delicate control on the component, structure, and surface of electrodes in lithium ion batteries are highly important to their performances in practical applications. Compared with various components and structures for electrodes, the choices for their surface are quite limited. The most widespread surface for numerous electrodes, a carbon shell, has its own issues, which stimulates the desire to find another alternative surface. Here, hydrogenated TiO₂ is exemplified as an appealing surface for advanced anodes by the growth of ultrathin hydrogenated TiO₂ branches on Mn₃O₄ nanorods. High theoretical capacity of Mn₃O₄ is well matched with low volume variation (∼4%), enhanced electrical conductivity, good cycling stability, and rate capability of hydrogenated TiO₂, as demonstrated in their electrochemical performances. The proof-of-concept reveals the promising potential of hydrogenated TiO₂ as a next-generation material for the surface in high-performance hybrid electrodes

Enhanced Lithium Storage Performances of Hierarchical Hollow MoS₂ Nanoparticles Assembled from Nanosheets

MoS₂, because of its layered structure and high theoretical capacity, has been regarded as a potential candidate for electrode materials in lithium secondary batteries. But it suffers from the poor cycling stability and low rate capability. Here, hierarchical hollow nanoparticles of MoS₂ nanosheets with an increased interlayer distance are synthesized by a simple solvothermal reaction at a low temperature. The formation of hierarchical hollow nanoparticles is based on the intermediate, K₂NaMoO₃F₃, as a self-sacrificed template. These hollow nanoparticles exhibit a reversible capacity of 902 mA h g^–1 at 100 mA g^–1 after 80 cycles, much higher than the solid counterpart. At a current density of 1000 mA g^–1, the reversible capacity of the hierarchical hollow nanoparticles could be still maintained at 780 mAh g^–1. The enhanced lithium storage performances of the hierarchical hollow nanoparticles in reversible capacities, cycling stability and rate performances can be attributed to their hierarchical surface, hollow structure feature and increased layer distance of S–Mo–S. Hierarchical hollow nanoparticles as an ensemble of these features, could be applied to other electrode materials for the superior electrochemical performance

High Electrochemical Performance of Monodisperse NiCo₂O₄ Mesoporous Microspheres as an Anode Material for Li-Ion Batteries

Binary metal oxides have been regarded as ideal and potential anode materials, which can ameliorate and offset the electrochemical performance of the single metal oxides, such as reversible capacity, structural stability and electronic conductivity. In this work, monodisperse NiCo₂O₄ mesoporous microspheres are fabricated by a facile solvothermal method followed by pyrolysis of the Ni_0.33Co_0.67CO₃ precursor. The Brunauer–Emmett–Teller (BET) surface area of NiCo₂O₄ mesoporous microspheres is determined to be about 40.58 m² g^–1 with dominant pore diameter of 14.5 nm and narrow size distribution of 10–20 nm. Our as-prepared NiCo₂O₄ products were evaluated as the anode material for the lithium-ion-battery (LIB) application. It is demonstrated that the special structural features of the NiCo₂O₄ microspheres including uniformity of the surface texture, the integrity and porosity exert significant effect on the electrochemical performances. The discharge capacity of NiCo₂O₄ microspheres could reach 1198 mA h g^–1 after 30 discharge–charge cycles at a current density of 200 mA g^–1. More importantly, when the current density increased to 800 mA·g^–1, it can render reversible capacity of 705 mA h g^–1 even after 500 cycles, indicating its potential applications for next-generation high power lithium ion batteries (LIBs). The superior battery performance is mainly attributed to the unique micro/nanostructure composed of interconnected NiCo₂O₄ nanocrystals, which provides good electrolyte diffusion and large electrode–electrolyte contact area, and meanwhile reduces volume change during charge/discharge process. The strategy is simple but very effective, and because of its versatility, it could be extended to other high-capacity metal oxide anode materials for LIBs

All supplementary materials from Amorphous mesoporous GeO<i>_x</i> anode for Na-ion batteries with high capacity and long lifespan

This file includes the experimental details like test instruments and test parameters. The XRD patterns, cycling performance and CV curves are also included

Polyaniline-Assisted Synthesis of Si@C/RGO as Anode Material for Rechargeable Lithium-Ion Batteries

A novel approach to fabricate Si@carbon/reduced graphene oxides composite (Si@C/RGO) assisted by polyaniline (PANI) is developed. Here, PANI not only serves as “glue” to combine Si nanoparticles with graphene oxides through electrostatic attraction but also can be pyrolyzed as carbon layer coated on Si particles during subsequent annealing treatment. The assembled composite delivers high reversible capacity of 1121 mAh g^–1 at a current density of 0.9 A g^–1 over 230 cycles with improved initial Coulombic efficiency of 81.1%, while the bare Si and Si@carbon only retain specific capacity of 50 and 495 mAh g^–1 at 0.3 A g^–1 after 50 cycles, respectively. The enhanced electrochemical performance of Si@C/RGO can be attributed to the dual protection of carbon layer and graphene sheets, which are synergistically capable of overcoming the drawbacks of inner Si particles such as huge volume change and low conductivity and providing protective and conductive matrix to buffer the volume variation, prevent the Si particles from aggregating, enhance the conductivity, and stabilize the solid–electrolyte interface membrane during cycling. Importantly, this method opens a novel, universal graphene coating strategy, which can be extended to other fascinating anode and cathode materials

A Deep Reduction and Partial Oxidation Strategy for Fabrication of Mesoporous Si Anode for Lithium Ion Batteries

A deep reduction and partial oxidation strategy to convert low-cost SiO₂ into mesoporous Si anode with the yield higher than 90% is provided. This strategy has advantage in efficient mesoporous silicon production and <i>in situ</i> formation of several nanometers SiO₂ layer on the surface of silicon particles. Thus, the resulted silicon anode provides extremely high reversible capacity of 1772 mAh g^–1, superior cycling stability with more than 873 mAh g^–1 at 1.8 A g^–1 after 1400 cycles (corresponding to the capacity decay rate of 0.035% per cycle), and good rate capability (∼710 mAh g^–1 at 18A g^–1). These promising results suggest that such strategy for mesoporous Si anode can be potentially commercialized for high energy Li-ion batteries

Direct Synthesis of Few-Layer F‑Doped Graphene Foam and Its Lithium/Potassium Storage Properties

Heteroatom-doped graphene is considered a potential electrode materials for lithium-ion batteries (LIBs). However, potassium-ion batteries (PIBs) systems are possible alternatives due to the comparatively higher abundance. Here, a practical solid-state method is described for the preparation of few-layer F-doped graphene foam (FFGF) with thickness of about 4 nm and high surface area (874 m²g^–1). As anode material for LIBs, FFGF exhibits 800 mAh·g^–1 after 50 cycles at a current density of 100 mA·g^–1 and 555 mAh·g^–1 after 100 cycles at 200 mA·g^–1 as well as remarkable rate capability. FFGF also shows 165.9 mAh·g^–1 at 500 mA·g^–1 for 200 cycles for PIBs. Research suggests that the multiple synergistic effects of the F-modification, high surface area, and mesoporous membrane structures endow the ions and electrons throughout the electrode matrix with fast transportation as well as offering sufficient active sites for lithium and potassium storage, resulting in excellent electrochemical performance. Furthermore, the insights obtained will be of benefit to the design of reasonable electrode materials for alkali metal ion batteries

Ultramicroporous Carbon through an Activation-Free Approach for Li–S and Na–S Batteries in Carbonate-Based Electrolyte

We report an activation-free approach for fabricating ultramicroporous carbon as an accommodation of sulfur molecules for Li–S and Na–S batteries applications in carbonate-based electrolyte. Because of the high specific surface area of 967 m² g^–1, as well as 51.8% of the pore volume is contributed by ultramicropore with pore size less than 0.7 nm, sulfur cathode exhibits superior electrochemical behavior in carbonate-based electrolyte with a capacity of 507.9 mA h g^–1 after 500 cycles at 2 <i>C</i> in Li–S batteries and 392 mA h g^–1 after 200 cycles at 1 <i>C</i> in Na–S batteries, respectively