Examining the Long-Term Cyclabilities of Li[Ni1/2Mn3/2]O4 and Li[Li0.1Al0.1Mn1.8]O4 Using a Full-Cell Configuration Including LTO-Counter Electrodes with Extra Capacity

In this study, a novel cell configuration was developed for evaluating the cyclabilities of lithium insertion materials. In this cell, the Li[Li1/3Ti5/3]O-4 (LTO) counter electrode has excess capacity on both the charge and discharge sides (EQ-LTO). The EQ-LTO/Li[Ni1/2Mn3/2]O-4 (LiNiMO) cell shows superior cyclability when compared to other cell configurations, such as Li/LiNiMO and LTO/LiNiMO cells. In Li/LiNiMO cells, drastic capacity fading is observed within 100 cycles. While LTO/LiNiMO cells are suited for long-term use, capacity fading occurs mainly due to the different charge states of LTO and LiNiMO rather than the deterioration of LiNiMO. Herein, long-term (more than 6 months) cycling tests are performed for Li[Li0.1Al0.1Mn1.8]O-4 (LAMO) in an EQ-LTO cell to assess whether this cell configuration is suitable for evaluating long term cyclabilities; LAMO in this cell shows higher capacity retention than that in an LTO cell. The capacity fading as a function of cycle number is found to be very small for LAMO (10 ppm cycle(-1)). From these results, we concluded that the EQ-cell configuration provides accurate capacity fading values for lithium insertion materials. (C) 2020 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.