Jinxiang Dai

Low‐Temperature Synthesized LiV3 O 8 as a Cathode Material for Rechargeable Lithum Batteries

LiV{sub 3}O{sub 8} was synthesized at 300--350 C by reaction of Li{sub 2}CO{sub 3} and NH{sub 4}VO{sub 3} which were blended in an aqueous solution. The product was termed LT LiV{sub 3}O{sub 8} and its preparation reaction was studied by thermographic analyses-depolarization thermocurrent. LT LiV{sub 3}O{sub 8} showed a high discharge capacity of 300 mAh/g active material, and maintained a capacity of 275 mAh/g after 15 cycles. Its electrochemical behavior as a cathode material for rechargeable lithium batteries was studied by galvanostatic charge-discharge and cyclic voltammetry. The structure and morphology of LT LiV{sub 3}O{sub 8} were characterized by infrared, X-ray diffraction, scanning electron microscopy, and their relationships with good electrochemical performance were studied.

Structural stability of aluminum stabilized alpha nickel hydroxide as a positive electrode material for alkaline secondary batteries

Abstract Nanostructured, aluminum-stabilized nickel, hydroxides described as Ni 1− x Al x (OH) 2 .(CO 3 ) x /2 · n H 2 O ( x =0.05–0.2), which are similar to α-Ni(OH) 2 · x H 2 O in crystal structure are examined as cathode materials for Ni–Cd cells. The structure, morphology and electrochemical performance are investigated. The structural changes and stability of nanophase aluminum-stabilized, alpha nickel hydroxides with different x values analyzed during cycling by means of powder X-ray diffraction. Compared with β-Ni(OH) 2 , the nanophase, aluminum-stabilized α-Ni(OH) 2 with x =0.15 is highly stable against overcharge.

Synthesis and characterization of the hollandite-type MnO2 as a cathode material in lithium batteries

Hollandite-type MnO2 (HMDO) with hydronium as tunnel counter ion was synthesized by oxidation of MnSO4 with ozone in a concentrated sulfuric acid solution.Its composition and structure were analyzed and characterized by inductive coupled plasma atomic emission spectrometry (ICP-AES), titration, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM).Hydronium can be exchanged with hydrated lithium ion and the exchanged HMDO can be dehydrated at 300°C. Cyclic voltammetry and galvanostatic charge–discharge study showed that HMDO with lithium ion exchanged and dehydrated had potential to be used as a cathode material in lithium secondary batteries.

Thin Film Copper Vanadium Oxide Electrodes for Thermal Batteries

In this work, thin film copper vanadium oxide electrodes including Cu3V2O8 and Cu5V2O10 were prepared by an aqueous process for thermal batteries. The electrochemical performances of thin film electrodes were tested and evaluated in thermal cells. Comparing with pressed pellet electrodes, the thin film electrodes were able to deliver higher specific capacities. Without any organic solvent and binder, the process for making the film electrodes is low cost and environmental benign.

A new form of vanadium oxide for use as a cathode material in lithium batteries

Abstract A new form of vanadium oxide, (Na 2 O) 0.23 V 2 O 5 , is synthesised by precipitation of sol and removing water. Its performance as a cathode material is studied by chronopotentiometry and cyclic voltammetry. A capacity of more than 220 mA h g −1 can be obtained in 12 cycles when the voltage is from 3.8 to 1.8 V. Its capacity and cyclability are satisfactory in comparison with other forms of vanadium oxide and synthesis is relatively easy. X-ray diffraction (XRD) studies show that (Na 2 O) 0.23 V 2 O 5 is quasi-tetragonal crystal after heating at a temperature below 250°C. The crystallites of (Na 2 O) 0.23 V 2 O 5 are in platelet form, and their dimensions are less than 2 μ m. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies found that the sol-precipitate, (Na 2 O) 0.23 V 2 O 5 · x H2O, can lose water at 200°C.

Preparation and Characterization of Nanostructured FeS 2 and CoS 2 for High-Temperature Batteries

In this paper, we report on the preparation of synthetic FeS 2 and CoS 2 using a relatively inexpensive aqueous process. This avoids the material and handling difficulties associated with a high-temperature approach. An aqueous approach also allows ready scale-up to a pilot-plant size facility. The FeS 2 and CoS 2 were characterized with respect to their physical and chemical properties. The synthetic disulfides were incorporated into catholyte mixes for testing in single cells and batteries over a range of temperatures. The results of these tests are presented and compared to the performance of natural FeS 2 (pyrite) and a commercial source of CoS 2 .

Thermal-sprayed, thin-film pyrite cathodes for thermal batteries-discharge-rate and temperature studies in single cells

Using an optimized thermal-spray process, coherent, dense deposits of pyrite (FeS/sub 2/) with good adhesion were formed on 304 stainless steel substrates (current collectors). After leaching with CS/sub 2/ to remove residual free sulfur, these served as cathodes in Li(Si)/FeS/sub 2/ thermal cells. The cells were tested over a temperature range of 450/spl deg/C to 550/spl deg/C under baseline loads of 125 and 250 mA/cm/sup 2/, to simulate conditions found in a thermal battery. Cells built with such cathodes outperformed standard cells made with pressed-powder parts. They showed lower interfacial resistance and polarization throughout discharge, with higher capacities per mass of pyrite. Post-treatment of the cathodes with Li/sub 2/O coatings at levels of >7% by weight of the pyrite was found to eliminate the voltage transient normally observed for these materials. Results equivalent to those of standard lithiated catholytes were obtained in this manner. The use of plasma-sprayed cathodes allows the use of much thinner cells for thermal batteries since only enough material needs to be deposited as the capacity requirements of a given application demand.