1. Carbon coating on the current collector and LiFePO4 nanoparticles - Influence of sp2 and sp3-like disordered carbon on the electrochemical properties
- Author
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Swain, P., Viji, M., Mocherla, P.S.V., and Sudakar, C.
- Subjects
Raman scattering ,Electric current collectors ,Cathodes ,Cyclic voltammetry ,Lithium alloys ,Disordered carbon ,Lithium compounds ,Electrochemical performance ,Carbon ,Charge transfer ,Coatings ,Electrochemical properties ,LiFePO ,Polarization effect ,Sol-gels ,Nanoparticles ,Electrochemical impedance spectra ,Aluminum coatings ,Electric discharges ,Charge transfer resistance ,Current collector ,Aluminum foil ,Electrodes ,Charging/discharging ,Aluminum - Abstract
The charging/discharging cycles, rate capabilities, cyclic voltammetry and electrochemical impedance spectra (EIS) of sol-gel prepared C-coated LiFePO4 (C-LFP-SG) and a commercial LiFePO4 (LFP-comm), in combination with two different current collectors, viz. Al foil and C-coated Al foil (Al-C) are studied. A flat voltage profile at ?3.4 V was seen during the charging/discharging cycle of C-LFP-SG/Al. However, C-LFP-SG/Al-C showed a continuous decrease in voltage during discharging and an increase during charging cycles. On contrary, LFP-comm/Al-C showed a constant flat voltage profile, whereas LFP-comm/Al shows a slight decrease during the discharge. C-LFP-SG/Al and LFP-comm/Al-C cells exhibit better electrochemical performance compared to C-LFP-SG/Al-C and LFP-comm/Al respectively. This is also reflected from a direct correlation between the flat potential behavior and their rate capabilities. From EIS measurements, we discuss the effect of C-coating on the charge-transfer resistances of LFP nanoparticles and current collectors. Raman analysis of carbon modes in all the cathodes and current collectors reveal that a large contribution from sp2 bonded carbon gives better electrochemical properties. Increasing sp3-like disordered carbon at the C-C interface leads to large polarization effects during the charging and discharging cycles. � 2015 Elsevier B.V. All rights reserved.
- Published
- 2015