Zuxiang Lin

Preparation and Electrochemical Performance of Spinel-Type Compounds Li4Al y Ti5 − y O 12 ( y = 0 , 0.10, 0.15, 0.25)

Li 4 Ti 5 O 1 2 and Al 3 + doped Li 4 Al y Ti 5 - y O 1 2 (y = 0.10, 0.15, 0.25) were synthesized via solid-state reaction using TiO 2 -rutile, Li 2 CO 3 , and Al 2 O 3 as starting reagents. The charge-discharge cycling of the cells showed that the electrochemical performance of Li 4 Ti 5 O 1 2 prepared from rutile-type TiO 2 by our laboratory was as good as that produced by anatase-type TiO 2 . However, Al 3 + doped Li 4 Al y Ti 5 - y O 1 2 (y = 0.10, 0.15) exhibited a much better electrochemical performance in comparison with undoped Li 4 Ti 5 O 1 2 . Among the three samples of Li 4 Al y Ti 5 - y O 1 2 (y = 0, 0.10, 0.15), Li 4 Al 0 . 1 5 Ti 4 . 8 5 O 1 2 exhibited the largest reversible capacity and the highest coulombic efficiency. The discharge capacity values in the first and second cyclings were 195.6 and 173.6 mAh/g, respectively. The value remained 166.9 mAh/g after 30 cycles with a capacity loss of 3.86% compared to the second cycle, and the coulombic efficiency was 99.2% at the 30th cycle.

Effects of alumina whisker in (PEO)8–LiClO4-based composite polymer electrolytes

Abstract This paper reports the morphological, electrical and mechanical characteristics of the PEO-based composite polymer electrolytes with alumina whisker as fillers. The SEM results showed that serious microcracks occurred in the pristine PEO–LiClO 4 polymer electrolytes when they were quenched at room temperature and spherulites were allowed to form in the electrolytes. Addition of alumina whisker effectively prevented the formation of the microcracks. The whiskers were homogeneously dispersed in the polymer electrolyte matrix and exhibited excellent interconnection with PEO–LiClO 4 polymer electrolyte. The addition of whisker additives improved the ionic conductivity of the PEO–LiClO 4 polymer electrolytes to some extent when the content of the whisker was less than 20 wt.%. Moreover, the whisker could remarkably improve the mechanical performance of the PEO–LiClO 4 polymer electrolyte especially at the temperatures higher than its melting point.

High-Performance Silicon/Carbon/Graphite Composites as Anode Materials for Lithium Ion Batteries

Silicon/carbon and silicon/carbon/graphite composites have been synthesized at room temperature using concentrated H 2 SO 4 as a dehydration agent. As a ductile matrix, the novel amorphous carbon obtained from the dehydration process could effectively buffer the volume change of silicon particles during discharge-charge cycling. The introduction of graphite in the silicon/carbon composite further improved the cycling performance. The composite with 30 wt % of amorphous carbon replaced by graphite demonstrated a stable capacity of 712.8 mAh g -1 and a high capacity retention ratio of 84.1% at 0.1 C over 50 cycles, suggesting it is a favorable candidate as anode material for lithium-ion batteries.

Synthesis by an EDTA-Based Soft-Chemistry Route and Characterization of Nanosized LiCoO2 Cathode Materials

The layered LiCoO 2 compound, which has been of great interest for lithium-ion batteries, was prepared in this paper by calcining an ethylenediaminetetraacetic acid (EDTA)-based complex precursor crystal at low temperatures. The details of the synthesis procedure are presented and a possible mechanism of formation for the EDTA/Co/Li complex precursor is discussed. The physical properties of the synthesized cathode materials are discussed in the light of structural (X-ray diffraction) and thermal (differential thermal) analyses. The charge and discharge cycling characteristics of cells containing the synthesized LiCoO 2 as positive electrode and lithium metals as anode with a nonaqueous electrolyte showed that the LiCoO 2 synthesized at 700°C exhibited much better performance than the materials obtained by conventional solid-state reaction techniques with a first cycle capacity of 167 mAh/g and specific capacity loss of about 11% for 30 cycles.

Parameter inversion of layered media covered by a rough surface

An inversion technique for estimating the structure parameters of layered media covered by a rough surface based on a genetic algorithm is proposed in this work. A theoretical model of scattering from three-dimensional arbitrary layered media with a 3D infinite rough surface based on the small perturbation method (SPM) is employed to calculate the forward scattering problem. The backscatting coefficients of multiple frequencies, angles and polarizations are used to create a nonlinear optimization problem. As the cost function has many local minima, a genetic algorithm is applied to help the inversion procedure converge to the global minimum. The inversion results show the method poses good tolerance to the input data with the additive white Gaussian noise.