High-rate performance of binder-free LiFePO4 cathode prepared by using various types of conductive carbons

Abstract

• A binder-free disc prepared by pressing the mixture of LiFePO 4 and holey graphene. • The binder-free disc has excellent electrical contact and flexibility. • The initial capacity of binder-free LiFePO 4 disc is 111.7 mAh cm -3 at the 1 C rate. • The binder-free LiFePO 4 disc exhibits excellent cycling stability in 150 cycles. A series of binder-free LiFePO 4 cathode discs prepared by dry-pressing the mixture of LiFePO 4 and various conductive carbon. Among those cathode discs, the cathode disc with thickness of 70 μm, prepared at the pressure of 334 MPa and composed of LiFePO 4 and layered holey graphene (CDLL-70 disc) exhibits the best electrochemical performance in the electrolyte of 1.0 mol L -1 lithium bis(trifluoromethanesulphonyl)imide and 0.1 mol L -1 LiNO 3 in ethylene glycol dimethyl ether: dioxolane in 1: 1 weight %. LiFePO 4 in the CDLL-70 disc exhibits the stable olivine structure (Space group: Pmnb, JCPDS 40-1499) after charge-discharged for 100 cycles. The CDLL-70 disc exhibits excellent electrical contact between LHG matrix and LiFePO 4 particles for homogeneous structure. The CDLL-70 disc exhibits the discharge capacity of 111.7 mAh cm -3 (138.2 mAh g -1 ) (1 st cycle) and 111.2 mAh cm -3 (137.5 mAh g -1 ) (150 th cycle), respectively. The capacity retention rate of the CDLL-70 disc in 150 cycles is 99.5%. Therefore, the CDLL-70 disc exhibits the excellent rate performance and cycle stability for its excellent flexibility.