Zhenghua Deng

A ( LiFePO4 – AC ) ∕ Li4Ti5O12 Hybrid Battery Capacitor

In this work, we synthesized a composite cathode material containing LiFePO 4 and activated carbon (AC), which is abbreviated as LAC, by a solid-state reaction, and assembled a hybrid battery-capacitor LAC/Li 4 Ti 5 O 12 . The electrochemical performances of the hybrid battery-capacitor LAC/Li 4 Ti 5 O 12 were characterized by cyclic voltammograms, constant current charge-discharge, rate charge-discharge, and cycle performance testing. The results show the hybrid battery-capacitor LAC/Li 4 Ti 5 O 12 has advantages of the high rate capability of hybrid capacitor AC/Li 4 Ti 5 O 12 and the high capacity of battery LiFePO 4 /Li 4 Ti 5 O 12 . It is also proven that the hybrid battery-capacitor LAC/Li 4 Ti 5 O 12 is an energy storage device where the capacitor and the secondary battery coexist in one cell system.

Kinetic analysis of one-step solid-state reaction for Li4Ti5O12/C.

The kinetics of one-step solid-state reaction of Li(4)Ti(5)O(12)/C in a dynamic nitrogen atmosphere was first studied by means of thermogravimetric-differential thermal analysis technique at five different heating rates. According to the double equal-double steps method, the Li(4)Ti(5)O(12)/C solid-state reaction mechanism could be properly described as the Jander equation, which was a three-dimensional diffusion with spherical symmetry, and the reaction mechanism functions were listed as follows: f(α) = (3)/(2)(1 - α)(2/3)[1 - (1 - α)(1/3)](-1), G(α) = [1 - (1 - α)(1/3)](2). In FWO method, average activation energy, frequency factor, and reaction order were 284.40 kJ mol(-1), 2.51 × 10(18) min(-1), and 1.01, respectively. However, the corresponding values in FRL method were 271.70 kJ mol(-1), 1.00 × 10(17) min(-1), and 0.96, respectively. Moreover, the values of enthalpy of activation, Gibbs free energy of activation, and entropy of activation at the peak temperature were 272.06 kJ mol(-1), 240.16 kJ mol(-1), and 44.24 J mol(-1) K(-1), respectively.

Single-ion conduction and electrochemical characteristics of poly(oxyethylene)/lithium methoxy oligo(oxyethylene) sulfate blend

Abstract The ion conduction of a blend of poly(oxyethylene) (PEO) and lithium methoxy oligo(oxyethylene) sulfate (SAL8) and its electrochemical characteristics were studied. The maximum ambient conductivity of the blend reaches 1.2 × 10−6 S/cm. The blend exhibits single-ion conduction, excellent mechanical performance, and electrochemical stability. A battery of Li/PEO + SAL8/Li1+xV3O8 has a constant discharge capacity at different discharge current densities up to a certain voltage, while the discharge capacity of Li/P (MEO16-AM) + LiClO4/Li1+xV3O8 decreases with an increase of the discharge current density.

Electrochemical characteristics of lithium intercalation into natural gas coke serving as the negative electrode of a lithium battery

Abstract The electrochemical characteristics of a new type of coke for the negative electrode of a lithium ion battery are investigated. This coke is prepared from natural gas by means of thermoplasma technology. The initial discharge–charge properties of natural gas coke of several kinds are discussed. The effects of surface modification of cokes on the characteristics of lithium intercalation during the first cycle are also explored. The properties of lithium intercalation into carbon electrodes show that the electrochemical behaviour is determined by the nature of the carbon material. The results also demonstrate that the surface properties of carbon electrodes remarkably influence the efficiency of the first cycle. Surface modification of coke electrodes with polymer can increase the initial coulombic efficiency but reduces the initial discharge capacity.

Syntheses of lithium oligoether phenylsulfonates

Abstract Lithium oligoether phenylsulfonates, a new kind of oligoether salts which are used in ionic conductive polymers, were synthesized. IR, 1HNMR spectra and elemental analyses were used to characterize their chemical structures. DSC results exhibit that the salts have low glass transition temperature (-30°C ∽ -20 °C). They are viscous liquids at ambient temperature and could be used as low temperature molten salts in polymer electrolytes.