In situ modification of LiMn3/4Fe1/4PO4/C cathode realized by hierarchical porous α-LiAlO2 as channel for lithium-ion batteries

Abstract

In view of the lower electronic and ionic conductivity of LiMnPO4 cathode materials, we use α-LiAlO2 solid electrolyte with pore structure to compound LiMn3/4Fe1/4PO4/C solid solution on the basis of Mn site doped Fe, forming a conductive connection network between them. Using anode aluminum oxide as porous structure template, a series of LiMn3/4Fe1/4PO4/C@α-LiAlO2 nano composites are constructed by hydrothermal in-situ deposition and subsequent heat treatment. Through the first-principles calculation, it is found that the modification of α-LiAlO2 leads to an increase in the number of states near Fermi level, and the adjustment energy band width affects the electronic conductivity of LiMn3/4Fe1/4PO4 electrode. When the content of α-LiAlO2 is 6 wt%, the electronic structure of LiMn3/4Fe1/4PO4@α-LiAlO2 composite is the best and has the best performance. This material material exhibits a better specific discharge capacity, that is, 142.6, 137.7, 130.3, 117.1, 100.6, 79.2 and 68.5 mAh·g−1 at 0.5C, 2C, 4C, 8C, 10C, 15C and 20C, respectively. In addition, its DLi + is 2.02 × 10−12 cm2·s−1, which is an order of magnitude higher than that of other α-LiAlO2-containing electrodes. Hence, it is significant in cathode for lithium-ion batteries to reasonably design multi-functional hybrid materials.