title: Conformal Coating Strategy Comprising N-doped Carbon and Conventional Graphene for Achieving Ultrahigh Power and Cyclability of LiFePO4.
abstract: Surface carbon coating to improve the inherent poor electrical conductivity of lithium iron phosphate (LiFePO4, LFP) has been considered as most efficient strategy. Here, we also report one of the conventional methods for LFP but exhibiting a specific capacity beyond the theoretical value, ultrahigh rate performance, and excellent long-term cyclability: the specific capacity is 171.9 mAh/g (70 μm-thick electrode with ∼10 mg/cm(2) loading mass) at 0.1 C (17 mA/g) and retains 143.7 mAh/g at 10 C (1.7 A/g) and 95.8% of initial capacity at 10 C after 1000 cycles. It was found that the interior conformal N-C coating enhances the intrinsic conductivity of LFP nanorods (LFP NR) and the exterior reduced graphene oxide coating acts as an electrically conducting secondary network to electrically connect the entire electrode. The great electron transport mutually promoted with shorten Li diffusion length on (010) facet exposed LFP NR represents the highest specific capacity value recorded to date at 10 C and ultralong-term cyclability. This conformal carbon coating approach can be a promising strategy for the commercialization of LFP cathode in lithium ion batteries.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea.
authors.forename: Kan
authors.initials: K
authors.lastname: Zhang
authors.affiliation: SKKU Advanced Institute of Nanotechnology (SAINT) and School of Chemical Engineering, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Jeong-Taik
authors.initials: JT
authors.lastname: Lee
authors.affiliation: SKKU Advanced Institute of Nanotechnology (SAINT) and School of Chemical Engineering, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Materials Science and Engineering, Eng 1-123, Pohang University of Science and Technology (POSTECH) , 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk 790-784, Republic of Korea.
authors.forename: Byoungwoo
authors.initials: B
authors.lastname: Kang
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea.
authors.forename: Jung Hyun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: SKKU Advanced Institute of Nanotechnology (SAINT) and School of Chemical Engineering, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Gi-Ra
authors.initials: GR
authors.lastname: Yi
authors.affiliation: Department of Chemical and Biomolecular Engineering, Yonsei University , 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea.
authors.forename: Jong Hyeok
authors.initials: JH
authors.lastname: Park
keywords: Li ion diffusion; LiFePO4 cathode; conformal coating strategy; electrode conductivity; intrinsic conductivity