One-pot formation of N, S-doped carbon coated-LiFePO4 with improved lithium storage performance

Olivine-type lithium iron phosphate (LFP) serves as a prominent cathode material for Li-ion batteries, attributed to its natural abundance, remarkable cycling stability, eco-friendliness, and cost-effectiveness. Nonetheless, its additional utilization has been constrained by its inherent low conductivity and sluggish lithium-ion diffusion rate. Incorporation of heteroatom-doped carbon coatings serves as an effective method to enhance the electrochemical properties of LFP, leading to a notable improvement in both the electronic and ionic conductivity of the material. At present, however, the preparation of heteroatom-doped carbon cladding layer is mostly done by secondary sintering method, which is too cumbersome. In this paper, lithium iron phosphate containing N- and S-element doped carbon layers is synthesized by a simple one-step ball milling method using zein as a source of carbon layers and heteroatoms. The results show that the N- and S-doped carbon-coated lithium iron phosphate prepared from zein has lower polarization by enhancing the diffusion kinetics of the lithium-ion battery. NS/C15@LFP shows an initial discharge specific capacity of 155.97 mAh·g −1 at 0.1C and still shows 84.06 mAh·g −1 at 20C. After returning to 0.1C, there is still a discharge capacity of 161.4 mAh·g −1 . The capacity retention rate is 87 % after 500 cycles at 1C and 89 % after 500 cycles at the high current density of 5C, suggesting its excellent electrochemical performance. This work shows that lithium iron phosphate coating N- and S-doped carbon synthesized by using zein as the carbon source and heteroatom donor is a simple and low-cost strategy that gives LFP excellent electrochemical performance.