Tin Oxide Based Composites Derived Using Electrostatic Spray Deposition Technique as Anodes for Li-Ion Batteries

Authors

Abirami Dhanabalan, Florida International UniversityFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Materials Science and Engineering

First Advisor's Name

Chunlei Wang

First Advisor's Committee Title

Committee Co-Chair

Second Advisor's Name

Surendra K. Saxena

Second Advisor's Committee Title

Committee Co-Chair

Third Advisor's Name

Wenzhi Li

Fourth Advisor's Name

Norman D.H. Munroe

Fifth Advisor's Name

W. Kinzy Jones

Keywords

Lithium ion battery, anodes, energy storage, tin oxide

Date of Defense

11-8-2012

Abstract

Recent advances in the electric & hybrid electric vehicles and rapid developments in the electronic devices have increased the demand for high power and high energy density lithium ion batteries. Graphite (theoretical specific capacity: 372 mAh/g) used in commercial anodes cannot meet these demands. Amorphous SnO₂ anodes (theoretical specific capacity: 781 mAh/g) have been proposed as alternative anode materials. But these materials have poor conductivity, undergo a large volume change during charging and discharging, large irreversible capacity loss leading to poor cycle performances.

To solve the issues related to SnO₂ anodes, we propose to synthesize porous SnO₂ composites using electrostatic spray deposition technique. First, porous SnO₂/CNT composites were fabricated and the effects of the deposition temperature (200,250, 300 ^oC) & CNT content (10, 20, 30, 40 wt %) on the electrochemical performance of the anodes were studied. Compared to pure SnO₂ and pure CNT, the composite materials as anodes showed better discharge capacity and cyclability. 30 wt% CNT content and 250 ^oC deposition temperature were found to be the optimal conditions with regard to energy capacity whereas the sample with 20% CNT deposited at 250 ^oC exhibited good capacity retention. This can be ascribed to the porous nature of the anodes and the improvement in the conductivity by the addition of CNT. Electrochemical impedance spectroscopy studies were carried out to study in detail the change in the surface film resistance with cycling. By fitting EIS data to an equivalent circuit model, the values of the circuit components, which represent surface film resistance, were obtained. The higher the CNT content in the composite, lower the change in surface film resistance at certain voltage upon cycling. The surface resistance increased with the depth of discharge and decreased slightly at fully lithiated state.

Graphene was also added to improve the performance of pure SnO₂ anodes. The composites heated at 280 ^oC showed better energy capacity and energy density. The specific capacities of as deposited and post heat-treated samples were 534 and 737 mAh/g after 70 cycles. At the 70^th cycle, the energy density of the composites at 195 °C and 280 °C were 1240 and 1760 Wh/kg, respectively, which are much higher than the commercially used graphite electrodes (37.2-74.4 Wh/kg). Both SnO₂/CNTand SnO₂/grapheme based composites with improved energy densities and capacities than pure SnO₂ can make a significant impact on the development of new batteries for electric vehicles and portable electronics applications.

Identifier

FI12121003

Recommended Citation

Dhanabalan, Abirami, "Tin Oxide Based Composites Derived Using Electrostatic Spray Deposition Technique as Anodes for Li-Ion Batteries" (2012). FIU Electronic Theses and Dissertations. 801.
https://digitalcommons.fiu.edu/etd/801