A high-performance LiCoPO4/C core/shell composite for Li-ion batteries

In this work, we report a LiCoPO4/C core/shell structure to address two key challenges facing the application of lithium cobalt phosphate (LiCoPO4), i.e. sluggish kinetics and poor cycle stability. By carefully controlling the synthetic procedure, we obtain a LiCoPO4 material coated with a homogeneous carbon shell via an in situ approach. The carbon shell not only increases the reversible capacity, but also enhances the capacity retention upon repeated cycles. Electrochemical charge and discharge tests show that the LiCoPO4/C core/shell structure can deliver a high specific capacity of 131 mAh g(-1) in the voltage range of 3.0-5.2 V vs. Li+/Li and maintain 78% of initial capacity after 40 cycles at a low specific current of 17 mA g(-1). When discharged at 1 C, the material still delivers a capacity of 95 mAh g(-1). The results indicate that the LiCoPO4/C composite is promising for energy storage application. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry, and AC impedance are applied to understand its good electrochemical performance. (C) 2012 Elsevier Ltd. All rights reserved.