Preparation and electrochemical properties of Al‐F co‐doped spinel LiMn 2 O 4 single‐crystal material for lithium‐ion battery

Spinel LiMn2O4 has the advantages of high voltage, high safety, low pollution, low cost, and rich resources. However, its low initial capacity, rapid-cycle decay, and other factors hinder its commercialization process. In this paper, a pure phase LiMn2O4 is synthesized by a high-temperature solid-phase method, and the element doping is used to modify it to improve its cycle performance. The results show that the optimal process conditions for preparing LiMn2O4 are: the Li/Mn ratio is 1.05:2, the calcination temperature is 780°C, and the calcination time is 15 hours. X-ray diffractometer reveals that the samples prepared by Al3+ and F− co-doping are still typical spinel structures. Scanning electron microscope shows that the sample is single-crystal Li1.05Al0.02Mn1.98F0.02O3.98 with uniform grain distribution and regular morphology. The sample has excellent cycle performance, and its initial discharge specific capacity is 115.5 mAh g−1 at 0.1C. The capacity retention rate is still above 80% after 367 cycles, and the specific capacity is 90.3 mAh g−1. The Al-F co-doped LiMn2O4 single-crystal material can effectively inhibit the Jahn-Teller effect, alleviate the dissolution of Mn, as well as increase the diffusion channel of Li+. This work provides a theoretical basis for promoting the development of LiMn2O4 cathode materials for lithium-ion batteries.