Electrochemical evaluation of mixed oxide electrode for Li-ion secondary batteries: Li1.1Mn1.9O4 and LiNi0.8Co0.15Al0.05O2

In attempt to utilize spinel compound, a blend type of positive electrode, Li1.1Mn1.9O4 and LiNi0.8Co0.15Al0.05O2 (1:1 in weight), was representatively investigated. Though spinel Li1.1Mn1.9O4 is modified by Li replacement at Mn sites, its capacity fading was inevitable by HF attack into the electrolyte at 25 °C and especially at 60 °C. The specific discharge capacity of the mixed positive electrode, Li1.1Mn1.9O4 and LiNi0.8Co0.15Al0.05O2 (1:1 in weight), had a sum average value of Li1.1Mn1.9O4 and LiNi0.8Co0.15Al0.05O2 electrodes. Interestingly, the mixed positive electrode had greatly improved capacity retention even at 60 °C. The capacity fading was only of about 8 mAh g−1 by applying 1 C rate (150 mA g−1) during 100 cycles. In the full cell test utilizing graphite as the negative electrode, the retained capacity was about 96% of its initial capacity by applying 1 C current at 25 °C. It is suggested that the mixed electrode is considered to be a quite promising positive electrode material to be applied for lithium-ion batteries.