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Structure and Performances of x LiFePO 4 /C·(1 − x ) Li 3 V 2 ( PO 4 ) 3 /C Cathode for Lithium‐Ion Batteries by Using Poly(vinyl alcohol) as Carbon Source
Author(s) -
Fan Changling,
Zhang Weihua,
Zeng Taotao,
Li Lingfang,
Zhang Xiang,
Han Shaochang
Publication year - 2015
Publication title -
bulletin of the korean chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.237
H-Index - 59
ISSN - 1229-5949
DOI - 10.1002/bkcs.10542
Subject(s) - cyclic voltammetry , vinyl alcohol , electrochemistry , cathode , lithium (medication) , analytical chemistry (journal) , scanning electron microscope , conductivity , materials science , carbon fibers , electrical resistivity and conductivity , composite number , crystallography , chemistry , electrode , organic chemistry , composite material , polymer , medicine , endocrinology , engineering , electrical engineering
Poly(vinyl alcohol), whose pyrolysis carbon possesses high conductivity of 8.88 × 10 −1 S/cm, was used to synthesize x LiFePO 4 /C·(1 − x ) Li 3 V 2 ( PO 4 ) 3 /C cathode. It was characterized by X‐ray diffraction, scanning electron microscopy, conductivity, cyclic voltammetry, and galvanostatic charge and discharge experiments. Results show that LiFePO 4 /C and Li 3 V 2 ( PO 4 ) 3 /C coexists in the cathode. The particles sizes of 0. 75LiFePO 4 /C·0. 25Li 3 V 2 ( PO 4 ) 3 /C (x = 0.75) are much smaller than 100 nm due to the role of poly(vinyl alcohol). Its conductivity is 8.79 × 10 −2 S/cm. The oxidative and reductive peaks in cyclic voltammetry are sharp and symmetrical. Their low potential gaps indicate that the extractions and insertions of lithium ion possess excellent reversibility. Its discharge capacities at 1 and 5 C are 141.1 and 100.1 mAh /g. The more Li 3 V 2 ( PO 4 ) 3 /C in cathode results in the deterioration of electrochemical performances due to its low theoretical capacity. It is concluded that poly(vinyl alcohol) is an effective carbon source in the preparation of x LiFePO 4 /C·(1 − x ) Li 3 V 2 ( PO 4 ) 3 /C composite cathode with excellent performances.