title: A chemically activated graphene-encapsulated LiFePO4 composite for high-performance lithium ion batteries.
abstract: A composite of modified graphene and LiFePO4 has been developed to improve the speed of charging-discharging and the cycling stability of lithium ion batteries using LiFePO4 as a cathode material. Chemically activated graphene (CA-graphene) has been successfully synthesized via activation by KOH. The as-prepared CA-graphene was mixed with LiFePO4 to prepare the composite. Microscopic observation and nitrogen sorption analysis have revealed the surface morphologies of CA-graphene and the CA-graphene/LiFePO4 composite. Electrochemical properties have also been investigated after assembling coin cells with the CA-graphene/LiFePO4 composite as a cathode active material. Interestingly, the CA-graphene/LiFePO4 composite has exhibited better electrochemical properties than the conventional graphene/LiFePO4 composite as well as bare LiFePO4, including exceptional speed of charging-discharging and excellent cycle stability. That is because the CA-graphene in the composite provides abundant porous channels for the diffusion of lithium ions. Moreover, it acts as a conducting network for easy charge transfer and as a divider, preventing the aggregation of LiFePO4 particles. Owing to these properties of CA-graphene, LiFePO4 could demonstrate enhanced and stably long-lasting electrochemical performance.
authors.affiliation: Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 151-742, Republic of Korea.
authors.forename: Jeonghyun
authors.initials: J
authors.lastname: Ha
authors.forename: Seung-Keun
authors.initials: SK
authors.lastname: Park
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Yu
authors.forename: Aihua
authors.initials: A
authors.lastname: Jin
authors.forename: Byungchul
authors.initials: B
authors.lastname: Jang
authors.forename: Sungyool
authors.initials: S
authors.lastname: Bong
authors.forename: In
authors.initials: I
authors.lastname: Kim
authors.forename: Yung-Eun
authors.initials: YE
authors.lastname: Sung
authors.forename: Yuanzhe
authors.initials: Y
authors.lastname: Piao
mesh_terms: D011211:Electric Power Supplies; D006108:Graphite / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry
chemical_list: D006878:Hydroxides; D007477:Ions; C473349:LiFePO4; D010710:Phosphates; D017680:Potassium Compounds; D006108:Graphite; D008094:Lithium; D007501:Iron; C029943:potassium hydroxide