Shahua Huang

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.

Room-Temperature Mechanosynthesis of Ni3S2 as Cathode Material for Rechargeable Lithium Polymer Batteries

The formation of Ni 3 S 2 was realized by mechanical alloying with metallic nickel and sulfur powder as precursors. The products were characterized by X-ray diffraction, thermoanalysis, and scanning electron microscopy. Electrochemical properties of Li/P(EO) 20 Li(CF 3 SO 2 ) 2 N-10 wt % γ-LiAlO 2 /Ni 3 S 2 cells were also presented. The initial discharge capacity of Ni 3 S 2 was 304 mAh g -1 , with a platform at about 1.4 V vs Li/Li + . A capacity fading rate of 0.5% per cycle was achieved within 100 cycles. The charge-discharge mechanism of Ni 3 S 2 was implied by the analysis of the charge-discharge potential profiles, the cyclic voltammetry traces, and the ex situ XRD patterns of the Ni 3 S 2 cathode.

Synthesis and the improved high-rate performance of LiMn2O4/Ag composite cathode for lithium-ion batteries

The LiMn 2 O 4 /Ag composite has been prepared by a chemical deposition of silver particles. Well dispersed and nanosized silver particles in the composites were realized by careful control of the preparation conditions. The experimental results showed that the 6.3 wt % Ag in the composite obviously reduced the impedance of the precursor and the polarization of the cathode/electrolyte interface in the cell and effectively improved the high rate cycling performance of LiMn 2 O 4 . The reversible capacity after 50 cycles remained at 103.2 mAh/g with capacity loss of 10.57% compared to the first cycle even at the charge-discharge rate as high as 10C.

Study on the Li + Insertion/Extraction for Silicon Nanosized Silver Composite Electrode

Nanosized silver particle (<10 nm) was highly dispersed on the surface of silicon particle by electroless deposition on the basis of a stirred silver mirror reaction. Ex situ X-ray diffraction and discharge/charge cycling measurements indicated that silver, as well as silicon, participated in the insertion/extraction process of Li + and played a positive role in the complete extraction of Li + from silicon host. Furthermore, ordered structure of silicon can be obtained after the extraction of Li + with the help of silver additives, which indicates the effect of silver additives in promoting the recrystallization of amorphous Li + -extracted silicon.