Electrochemical performance of 5 V LiNi0.5Mn1.5O4 cathode modified with lithium carbonate addition in electrolyte

LiNi 0.5 Mn 1.5 O 4 electrode modification is achieved in this work through adding inorganic lithium carbonate (Li 2 CO 3 ) into carbonate electrolyte. Superior cyclic stability of the cathode in the range of 5–2 V is attained, a capacity of 0.3698 mAh g −1 is lost per cycle, which is half of the value in the Li 2 CO 3 -free condition. The capacity loss above and below 3.5 V are both alleviated in the presence of Li 2 CO 3 . Its effect on both the electrolyte bulk and the cathode surface is analyzed with SEM , TEM and XPS measurements. The density functional theory (DFT) calculation is carried out to discuss the modification mechanism. It is speculated that Ni 4+ ⋯CO 3 2− coordination may be formed through the interaction between Ni and O, weakening the oxidizability of Ni 4+ on the electrode surface . In addition, Li 2 CO 3 can consume PF 5 in the electrolyte. The interphase film can also maintain thin and steady during the cycling within 5–2 V.