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As a most promising anode candidate, silicon has the shortcomings of low electron conductivity and high volume expansion of 300%, hindering its applications in lithium ion batteries (LIBs). In this study, one-dimension porous silicon nanowires (pSi-NWs) were prepared through a simple metal-assisted chemical etching process by using metallurgical silicon as raw material. To consolidate the structural integrity of pSi-NWs, a crossed carbon skeleton (c-Cs) was introduced into pSi-NWs via in-situ polymerization and carbonization process. The resultant pSi-NWs@c-Cs composite delivered the high capacity of 1253 mAh g −1 with good cycling stability as well as the notable rate capability (476 mAh g −1 at 4 A g −1 ), much superior to those of pSi-NWs and pSi-NWs@reduced graphene oxide composite. The enhanced electrochemical performance of pSi-NWs@c-Cs composite is attributed to the crossed carbon skeleton in constructing the advanced Si/C interface to more effectively improve the electron conductivity of pSi-NWs and acting as the protective shell to keep the structure integrity of pSi-NWs. As the additive of commercial graphite anode, 28% of capacity augment (460 mAh g −1 at 0.2 A g −1 ) was realized by adding 20 wt% of pSi-NWs@c-Cs composite into graphite, demonstrating its promising applications in LIBs. [ABSTRACT FROM AUTHOR]

Considerable attention has been paid to sodium-ion batteries (SIBs) for large-scale energy storage due to low cost and abundant Na source. Phosphorus (P) is proposed as a high-capacity SIB anode material with theoretical capacity of 2596 mAh g −1 . However, the large volume expansion of P during sodiation brings about a series of challenges, including rapid capacity decay and slow ion transport. In this work, we develop an amorphous P ( α P) anode material with cubic boron nitride (c-BN) as a mechanical skeleton wrapped by nanoporous graphene (pGra) networks, which can combine synergistically the advantages of pGra and c-BN, and hence simultaneously solve the challenges for the P-based anodes. The rigid nature of c-BN is effective to suppress the severe volume expansion during P sodiation process, while the porous network of pGra serves as transport channel for electrons and ions, offering short pathways for large-radii Na + ions diffusion. The α P/c-BN/pGra composite anode shows excellent cyclability with a stable specific capacity of ∼1000 mAh g −1 and ∼90% capacity retention after 100 cycles at a specific current of 50 mA g −1 . The rigid c-BN and flexible pGra provides a promising pathway for developing high performance alloy-based materials for low-cost SIBs. [ABSTRACT FROM AUTHOR]

In this study, a facile MgO template-assisted route has been proposed for the preparation of carbon@MoS 2 composites via a one-step hydrothermal method followed by a thermal annealing process. By using sucrose as a carbon source and commercial MgO powder as a structure-directing agent, a three-dimensional sphere-like carbon@MoS 2 nanoarchitecture was assembled by one-dimensional worm-like nanorods which were composed of few-layered MoS 2 nanosheets and amorphous carbon matrix. The influence of different amount of MgO template on the morphology, structure, and lithium storage performance of the carbon@MoS 2 composites is systematically investigated. The carbon@MoS 2 -2 composite synthesized with a Mo precursor: MgO molar ratio of 1:1 exhibits much higher reversible capacity (905.3 mAh g −1 after 100 cycles at a current density of 100 mA g −1 ) and better high-rate capability (503.4 mAh g −1 at 5000 mA g −1 ) than those of bare MoS 2 and template-free carbon@MoS 2 -0 composite. Impressively, superior cycling stability is achieved for the carbon@MoS 2 -2 composite with a capacity retention of 93.4% even after 400 charge/discharge cycles at 5000 mA g −1 . The excellent electrochemical performance for carbon@MoS 2 -2 composite can be ascribed to its unique hierarchical nanoarchitecture and synergetic effect between MoS 2 nanosheets and amorphous carbon. [ABSTRACT FROM AUTHOR]

Silicon has attracted widespread attention as one of the most promising anode materials for next-generation lithium-ion batteries. Herein, we report a scalable method for synthesizing the stacked Si nanosheets (s-SiNS) in molten salt by electro-deoxidation of attapulgite followed by an acid etching process. The s-SiNS consists of 3D stacked silicon nanosheets and abundant voids between them, which can accommodate volume expansion during lithiation/delithiation process. Ex-situ X-Ray powder diffraction and scanning electron microscope reveal that the formation of s-SiNS microstructure involved the stratified Ca 3 Si 3 O 9 intermediate and etching of unreacted SiO x by HF. Owing the typical void-contained 3D architecture, the s-SiNS anode delivers a high specific capacity of 3046 mAh g-1 with a high initial coulombic efficiency of 82.5% at 0.2 A g-1, and a high rate capability of 700 mAh g-1 at 4 A g-1. The s-SiNS anode also possesses good cyclability and can deliver a satisfying reversible specific capacity of 1205 mAh g-1 at 0.5 A g-1 after 200 cycles with a high capacity retention of 60.2%. More importantly, the results of this study provide a new strategy for scalable synthesizing void-contained 3D Si architecture with abundant attapulgite as feedstock, and might shed light on the high-value utilization of resourceful attapulgite. [Display omitted] [ABSTRACT FROM AUTHOR]

The vast volume expansion of Si anode during lithiation process leads to poor cyclability and low initial coulombic efficiency (ICE), and thus seriously hampers its applications in lithium-ion batteries (LIBs). To overcome these obstacles, in this study, a double core-shell structure stabilized hierarchical porous Si (p-Si) microsphere was synthesized through a graphene-involved electrostatic self-assembly process coupled with a solvent-confined TiO 2 (sc-TiO 2) monomicelle assembly strategy. The advanced solvent-confined monomicelle assembly process enables the uniform deposition of ultra-thin TiO 2 layer on p-Si@graphene (p-Si@G) microsphere. The G/sc-TiO 2 hybrid double shell layer can significantly consolidate porous structure of p-Si microsphere and simultaneously improve the ICE value of p-Si@G@sc-TiO 2 microsphere. The resulting p-Si@G@sc-TiO 2 composite shows a high capacity value of 2597.9 mAh g−1 at 0.2 A g−1 with a high ICE value of 80.59%. The p-Si@G@sc-TiO 2 composite also demonstrates excellent rate capability with capacity of 802.53 mAh g−1 at 8 A g−1 and outstanding cyclability with capacity retention of 68% (1005.1 mAh g−1) after 300 cycles at 2 A g−1, superior to that of p-Si, p-Si@G as well as p-Si@G@TiO 2 microsphere preparing by traditional sol-gel TiO 2 coating method, suggesting its promising applications in LIBs. [ABSTRACT FROM AUTHOR]

Binary metal oxides have been proved to possess better pseudocapacitive performance than single metal oxide analogies. Substitution of toxic and high-cost ions (Co and Mo) in binary metal oxides with low-cost and environmentally-friendly ions (Ni and Mn) is of great economic and environmental importance. In this paper, murdochite-type binary metal oxides (i.e., Ni 6 MnO 8) and binary metal oxides@carbon nanotubes (i.e., Ni 6 MnO 8 @CNTs) core-shell structure were synthesized via a facile hydrothermal approach followed by a calcination process. Electrochemical measurement results indicated that the synthesized Ni 6 MnO 8 @CNT core-shell structure showed a high specific capacitance of 1213 F g−1 at 1 A g−1 with two times capacitance value of Ni 6 MnO 8 at same current density. Even at the high current density of 20 A g−1, the Ni 6 MnO 8 @CNT core-shell structure can still deliver a high capacitance value of 711 F g−1, which value is also much higher than that of Ni 6 MnO 8 at the current density of 1 A g−1. With the prepared Ni 6 MnO 8 @CNT hybrid as positive electrode and activated-polyaniline-derived-carbon as negative electrode, an asymmetric supercapacitor cell (ASC) was successfully assembled. The assembled ASC device exhibited excellent pseudocapacitive performance with a high specific capacitance of 154 F g−1 at 1 A g−1 and a high energy density of 58.2 Wh kg−1 at a power density of 831.4 W kg−1. Even at a high power density of 16.6 kW kg−1, the ASC device can still deliver a high energy density of 23.1 Wh kg−1, suggesting the promising applications of Ni 6 MnO 8 @CNT hybrid in supercapacitors. [ABSTRACT FROM AUTHOR]