Daoping Tang

Nanostructured silicon/porous carbon spherical composite as a high capacity anode for Li-ion batteries

A nanostructured silicon/porous carbon spherical composite was prepared by a simple hydrothermal method using glucose as a carbon source and Pluronic F127 as a soft template/pore forming agent in the presence of silicon nanoparticles, and a subsequent carbonization process. In this composite, silicon nanoparticles were individually and separately coated with a porous carbon shell with a thickness of 15–20 nm and a pore size of 3–5 nm. The composite electrode exhibited excellent cycling stability and rate capability, delivering a stable capacity of 1607 mA h g−1 at a current density of 0.4 A g−1 after 100 cycles, and a reversible capacity of 1050 mA h g−1 even at a high current density of 10 A g−1. Detailed analysis of cyclic voltammetry and electrochemical impedance spectroscopy revealed that the composite showed favorable electrochemical kinetics due to the nano-sized porous carbon shell, which facilitated the formation of a solid electrolyte interface film and the transportation of Li ions and electrons, and decreased the charge transfer resistance, thus significantly improving the electrochemical performance compared with the bare nano-Si electrode.

Micro/nano-structured SnS2 negative electrodes using chitosan derivatives as water-soluble binders for Li-ion batteries

Micro/nano-structured SnS2 was prepared by a hydrothermal method using biomolecular l-cysteine and SnCl4·5H2O as sulfur source and tin source, respectively. The electrochemical performances of SnS2 electrodes were investigated using water-soluble binders of carboxymethyl chitosan (C-chitosan) and chitosan lactate, and compared with the conventional water-soluble sodium carboxymethyl cellulose (CMC) and non-aqueous polyvinylidene difluoride (PVDF). SnS2 electrode using the water-soluble binders (C-chitosan, chitosan lactate, and CMC) showed higher initial coulombic efficiency, larger reversible capacity, and better rate capabilities than that of PVDF. In addition, SnS2 electrode using C-chitosan binder exhibited somewhat worse cycling stability, but better rate capability at a high rate of 5C than CMC.

Novel core–shell structured Si/S-doped-carbon composite with buffering voids as high performance anode for Li-ion batteries

A novel core–shell structured Si/S-doped-carbon composite with buffering voids (Si/v-SC), was prepared by a facile hydrothermal method using glucose as carbon source and simultaneously chemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of Si@SiO2 nanoparticles, and followed by carbonization and removal of the SiO2 layer. The results showed that the Si nanoparticles were embedded in the S-doped-carbon buffer space to form a core–shell structure. Compared to the Si/carbon composite (Si/v-C) without S-doping in carbon layer, the Si/v-SC composite electrode showed improved cycling and rate performance, exhibiting a reversible capacity of 664 mA h g−1 over 300 cycles at the current of 0.4 A g−1 and a high capacity of 537 mA h g−1 even at 10 A g−1. The effects of S-doping on the properties of carbon material were further investigated. XRD and Raman test revealed that the S-doping increased the interspace of carbon crystal face, and improved the amorphous structure of carbon and thus the initial coulombic efficiency.

Facile synthesis of nanostructured Li4Ti5O12/PEDOT:PSS composite as anode material for lithium-ion batteries

A poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) coated Li4Ti5O12 (LTO/PP) composite is synthesized by a facile and convenient approach, which involves dispersing LTO in an aqueous solution of PEDOT:PSS, followed by rotary evaporation accompanied by an ultrasonic procedure. After the coating process, LTO is covered by a homogeneous PEDOT:PSS layer, which effectively improves the electrical conductivity and processing capability of LTO to form a more homogeneous electrode sheet, and thus impart more favorable electrochemical kinetics as compared with the pristine LTO electrode. The LTO/PP electrode exhibits better reversible capacity and rate capability compared with the LTO electrode, delivering a reversible capacity of 177.2 mA h g−1 at 0.1C and reaching a capacity of 169.1 mA h g−1 with a capacity retention of 97.8% after 100 cycles at 0.5C. At the rate of 10C, the LTO/PP electrode delivers a capacity as high as 161.1 mA h g−1 (91.0% of the value achieved at 0.1C), as compared to 144.5 mA h g−1 for the pristine LTO electrode.