Design and Synthesis of Layered Na₂Ti₃O₇ and Tunnel Na₂Ti₆O₁₃ Hybrid Structures with Enhanced Electrochemical Behavior for Sodium-Ion Batteries

A novel complementary approach for promising anode materials is proposed. Sodium titanates with layered Na2Ti3O7 and tunnel Na2Ti6O13 hybrid structure are presented, fabricated, and characterized. The hybrid sample exhibits excellent cycling stability and superior rate performance by the inhibition of layered phase transformation and synergetic effect. The structural evolution, reaction mechanism, and reaction dynamics of hybrid electrodes during the sodium insertion/desertion process are carefully investigated. In situ synchrotron X‐ray powder diffraction (SXRD) characterization is performed and the result indicates that Na+ inserts into tunnel structure with occurring solid solution reaction and intercalates into Na2Ti3O7 structure with appearing a phase transition in a low voltage. The reaction dynamics reveals that sodium ion diffusion of tunnel Na2Ti6O13 is faster than that of layered Na2Ti3O7. The synergetic complementary properties are significantly conductive to enhance electrochemical behavior of hybrid structure. This study provides a promising candidate anode for advanced sodium ion batteries (SIBs)

Synthesis of hierarchical Sn/SnO nanosheets assembled by carbon-coated hollow nanospheres as anode materials for lithium/sodium ion batteries

This journal is The Royal Society of Chemistry. Tin-based anode materials have aroused interest due to their high capacities. Nevertheless, the volume expansion problem during lithium insertion/extraction processes has severely hindered their practical application. In particular, nano-micro hierarchical structure is attractive with the integrated advantages of nano-effect and high thermal stability of the microstructure. Herein, hierarchical Sn/SnO nanosheets assembled by carbon-coated hollow nanospheres were successfully synthesized by a facile glucose-assisted hydrothermal method, in which the glucose served as both morphology-control agent and carbon source. The hierarchical Sn/SnO nanosheets exhibit excellent electrochemical performances owing to the unique configuration and carbon coating. Specifically, a reversible high capacity of 2072.2 mA h g-1 was observed at 100 mA g-1. Further, 964.1 mA h g-1 after 100 cycles at 100 mA g-1 and 820.4 mA h g-1 at 1000 mA g-1 after 300 cycles could be obtained. Encouragingly, the Sn/SnO also presents certain sodium ion storage properties. This facile synthetic strategy may provide new insight into fabricating high-performance Sn-based anode materials combining the advantages of both structure and carbon coating

Tuning the component ratio and corresponding sodium storage properties of layer-tunnel hybrid Na0.6Mn1-xNixO2cathode by a simple cationic Ni\u3csup\u3e2+\u3c/sup\u3edoping strategy

Manganese (Mn)-based cathodes with advantages of low-cost, environmental benign, high energy density are crucial for the commercial process of sodium ion batteries (SIBs). Layer-tunnel hybrid cathode, which aims to integrate high capacity of P2-type layered structure with excellent cycling stability, superior rate performance of tunnel structure, deserves great research efforts. To further enhance the respective performance, the ratio of layer-tunnel component in the hybrid Na 0.6 Mn 1-x Ni x O 2 was adjusted by a simple cationic Ni 2+ doping route. The crystal structure and electrochemical behavior of Na 0.6 Mn 1-x Ni x O 2 were carefully detected, compared and analyzed. The comprehensive results evidenced that the layered component ratio would rapidly increase with Ni 2+ doping. The structural parameters of pure phase would also be affected by varied Ni 2+ content. And 5% Ni doping could be an optimized point in terms of reversible capacity, cycling stability, rate performance and reaction kinetics. This study would reveal the dual-function of cationic doping in both macro scale component ratio and atomic scale crystal lattice parameter, and grasp new insight into the design and optimization of high performance hybrid cathode for SIBs

Synthesis Strategies and Structural Design of Porous Carbon-Incorporated Anodes for Sodium-Ion Batteries

© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Over the past decades, porous carbonaceous and carbon-incorporated composites have aroused tremendous attention owing to their unique properties such as high surface area, excellent accessibility to active sites, tunable morphologies and structures, and superior mass transport and diffusion. They have been widely investigated and applied in various fields, such as energy storage, absorption, water filtration, drug delivery, catalysis, and sensing. In the energy storage area, rechargeable sodium-ion batteries (SIBs) have attracted tremendous attention as the next-generation power plants for large-scale energy storage systems (EESs). However, their low energy density and power density, as well as their poor cyclability, are still the main challenges for SIBs, especially for the anode, which acts as a bottleneck. With the incorporation of appropriate porous carbonaceous materials, the disadvantages of large volume shrinkage and low electron conductivity of alloying- and conversion-based anode materials have been significantly alleviated. This review points out and summarizes the most recent developments in synthesis strategies and morphology control of porous carbonaceous materials and the corresponding carbonaceous-material-incorporated high performance anodes for SIBs. Furthermore, the remaining challenges associated with these composites and effective routes to enhance their performance are discussed

A novel Mn-based P2/tunnel/O3\u27 tri-phase composite cathode with enhanced sodium storage properties

A novel P2/tunnel/O3\u27 composite Na0.7Bi0.01MnO2 cathode is developed via the Na+-site modification of Bi3+ in layer structure Na0.7MnO2 for the first time. Superior electrochemical performance with a high capacity retention of ∼86.5% after 300 cycles at 2C is obtained. Moreover, the tri-phase structure can also serve as a model material, which intuitively evidences the environmental structural stability order: tunnel \u3e P2 \u3e O3\u27

Fe-Nx Sites enriched microporous carbon nanoflower planted with tangled bamboo-like carbon nanotube as a strong polysulfides anchor for lithium-sulfur batteries

Serious shuttle effect and sluggish conversion kinetics of lithium polysulfides (LiPSs) have a massive impact on obstructing the practical application of lithium-sulfur (Li-S) batteries. To address such issues, Fe-Nx sites enriched microporous nanoflowers planted with tangled bamboo-like carbon nanotubes (Fe-Nx-C/Fe3C-CNTs NFs) are found to be effective catalytic mediators with strong anchoring capabilities for LiPSs. The bamboo-like carbon nanotubes catalyzed by Fe3C/Fe entangled each other to form a conductive network, which encloses a flower-like microporous carbon core with embedded well-dispersed Fe-Nx active sites. As expected, electrons smoothly transfer along the dense conductive bamboo-like carbon network while the flower-like carbon core consisting of micropores induces the homogeneous distribution of tiny sulfur and favors the lithium ions migration with all directions. Meanwhile, Fe-Nx sites strongly trap long-chain LiPSs with chemical anchoring, and catalyze the redox conversion of LiPSs. Due to the aforementioned synergistic effects, the S@Fe-Nx-C/Fe3C-CNTs NFs cathode exhibited a remarkable specific capacity (635 mAh g(s)(-1)) at 3 C and a favorable capacity decay with 0.04% per cycle even after 400 cycles at 1 C. (C) 2020, Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd

Optimization of NixCo1-x-yMnySe2 composition for efficient sodium storage

Due to the low cost and the abundance of Na resources, sodium-ion batteries (SIBs) have emerged as leading candidates for next-generation energy storage devices. For Se-based anodes, large volume expansion during cycling leads to poor structural reversibility and fast capacity fade. To overcome it, the heterostructured Ni1/3-xCo1/3-yMn1/3-zSe2/MnSe2 is constructed via tuning metal ratio with good controllability, in which the functionalities of heterostructure in realizing high-performance SIBs is comprehensively studied. Benefiting from the synergistic effect of element ratio optimization and heterostructure construction, Ni1/3-xCo1/3-yMn1/3-zSe2/MnSe2 simultaneously realizes high capacity, fast Na+ storage performance, and long-cycling durability. Remarkably, it exhibits a specific capacity of around 400 mAh g−1 at 2 A g−1, and achieves a capacity retention as high as ∼ 99.9 % after 2000 cycles, outperforming most Se-based anodes. Therefore, this work not only demonstrates the significance of heterostructure engineering in a cubic NixCo1-x-yMnySe2 anode, but also opens a new avenue for achieving high-performance electrode materials based on heterostructure construction

A novel high voltage battery cathodes of Fe\u3csup\u3e2+\u3c/sup\u3e/Fe\u3csup\u3e3+\u3c/sup\u3esodium fluoro sulfate lined with carbon nanotubes for stable sodium batteries

Current trends in battery research are promoting the development of feasible methods to prepare electrode materials with new architectures that can meet the requirements of high energy density associated with sodium ion batteries (SIB). It is logical to use solid-state processing techniques to fabricate SIB electrode materials due to its ease of handling and capability for large-scale production. From the SIB standpoint, the sulfate based polyanionic system is well known for its high operating voltage. The present study utilizes a hitherto-unknown solid-state process with an entirely new composition to develop an electrode comprising earth abundant carbon, sodium, sulfur, fluorine, and iron materials. This new NaFeSO4F-CNT system, where CNT is carbon nanotube, obtained by the solid-state technique, exhibits a highly stable Fe2+/Fe3+redox couple and achieves a capacity of ∼110 mAg−1at 0.1C with capacity retention of \u3e91% after 200 cycles (1C). This is the best-ever reversible, high potential sulfate based cathode for sodium ion batteries reported to date. This study also provides an in-depth understanding of the outstanding electrochemical performance of this novel electrode. These findings can make it possible to achieve maximum performance from potential electrodes, when the operating temperature is limited to 350 °C or below