Cycling Stability of Lithium‐Ion Batteries Based on Fe–Ti‐Doped LiNi0.5Mn1.5O4 Cathodes, Graphite Anodes, and the Cathode‐Additive Li3PO4

Abstract This study addresses the improved cycling stability of Li‐ion batteries based on Fe–Ti‐doped LiNi 0.5 Mn 1.5 O 4 (LNMO) high‐voltage cathode active material and graphite anodes. By using 1 wt% Li 3 PO 4 as cathode additive, over 90% capacity retention for 1000 charge–discharge cycles and remaining capacities of 109 mAh g −1 are reached in a cell with an areal capacity of 2.3 mAh cm − 2 (potential range: 3.5–4.9 V). Cells without the additive, in contrast, suffer from accelerated capacity loss and increase polarization, resulting in capacity retention of only 78% over 1000 cycles. An electrolyte consisting of ethylene carbonate, dimethyl carbonate, and LiPF 6 is used without additional additives. The significantly improved cycling stability of the full cells is mainly due to two factors, namely, the low Mn III content of the Fe–Ti‐doped LNMO active material and the use of the cathode‐additive Li 3 PO 4 . Crystalline Li 3 PO 4 yields a drastic reduction of transition metal deposition on the graphite anode and prevents Li loss and the propagation of cell polarization. Li 3 PO 4 is added to the cathode slurry that makes it a very simple and scalable process, first reported herein. The positive effects of crystalline Li 3 PO 4 as electrode additive, however, should apply to other cell chemistries as well.