Affiliation:
1. State Key Laboratory of Marine Resource Utilization in South China Sea Key Laboratory of Research on Utilization of Si-Zr-Ti Resources of Hainan Province School of Materials Science and Engineering Hainan University Haikou 570228 China
2. National Laboratory of Solid State Microstructures Nanjing University Nanjing 210093 China.
3. Guangdong Key Laboratory for Hydrogen Energy Technologies School of Materials Science and Hydrogen Energy Foshan University Foshan 528000 China
Abstract
AbstractIn Li‐ion batteries, the origin of memory effect in Al‐doped Li4Ti5O12 has been revealed as the reversible Al‐ion switching between 8a and 16c sites in the spinel structure, but it is still not clear about that for olivine LiFePO4, which is one of the most important cathode materials. In this work, a series of Na‐doped and Ti‐doped LiFePO4 are prepared in a high‐temperature solid‐state method, electrochemically investigated in Li‐ion batteries and characterized by X‐Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Magic‐Angle‐Spinning Nuclear Magnetic Resonance (MAS NMR). Compared with non‐doped LiFePO4, the Ti doping can simultaneously suppress the memory effect and the Li−Fe anti‐site, while they are simultaneously enhanced by the Na doping. Meanwhile, the Ti doping improves the electrochemical performance of LiFePO4, opposite to the Na doping. Accordingly, a schematic diagram of phase transition is proposed to interpret the memory effect of LiFePO4, in which the memory effect is attributed to the defect of Li−Fe anti‐site.
Funder
National Natural Science Foundation of China
Key Research and Development Project of Hainan Province