Impact of microwave synthesis conditions on the rechargeable capacity of LiCoPO4 for lithium ion batteries

• Published in: Journal of applied electrochemistry Vol. 43; no. 3; pp. 271 - 278
• Main Authors: Rogers, Reginald E., Clarke, Garry M., Matthew, Olivia N., Ganter, Matthew J., DiLeo, Roberta A., Staub, Jason W., Forney, Michael W., Landi, Brian J.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.03.2013
• Subjects: Carbon; Cathodes; Chemistry; Chemistry and Materials Science; Electric potential; Electrochemistry; Energy density; Industrial Chemistry/Chemical Engineering; Lithium; Lithium-ion batteries; Microwaves; Original Paper; Phosphates; Physical Chemistry; Synthesis; Nanomaterials; Lithium cobalt phosphate; Microwave synthesis; Batteries
• ISSN: 0021-891X; 1572-8838
• DOI: 10.1007/s10800-012-0517-y

Lithium transition metal phosphates have the capability of improving cathode energy densities up to 800 Wh kg −1 , a 27 % increase over conventional cathode active material energy densities. In this study, the effect of base-to-acid (NH 4 OH:H 3 PO 4 ) stoichiometric conditions on the intrinsic reversible capacity of lithium cobalt phosphate (LiCoPO 4 ) active material are investigated through microwave synthesis and electrochemical testing. Variation in solution pH results in an increase of 69 mAh g −1 in achievable capacity. X-ray diffraction results show highly crystalline LiCoPO 4 , with particle sizes ranging from 200 nm to greater than 1 μm based upon scanning electron microscopy. Electrochemical analysis with 1 M LiPF 6 EC:EMC (1:2 v/v) provides the highest capacity over multiple cycles. A discharge capacity of 128 mAh g −1 (78 % of theoretical capacity) is achievable for intrinsic LiCoPO 4 without further treatment (e.g., carbon coating) at an effective 0.1 C rate with a proper constant current–constant voltage step. Analysis of reported synthesis techniques shows that microwave synthesis yields the highest capacity for the intrinsic LiCoPO 4 material to date.