Combination of Li-rich layered-oxide with O2 cathodes for high-energy Li-ion/Li-O2 hybrid batteries

Abstract

The energy density of commercial Li-ion batteries (LIBs) is limited by the specific capacity of intercalation-type cathodes. The Li-O2 batteries based on the conversion reaction of oxygen cathodes can deliver the superhigh specific capacity. Herein, the Li-rich layered-oxide 0.5Li2MnO3·0.5LiNi0.54Co0.16Mn0.16O2 (5/5 LLO) cathodes have been combined with O2 cathodes, in order to examine their synergistic effect on cell performance. It is found that the hybrid cells deliver the discharge capacity of 458 mAh [Formula: see text] at approximately 0.2 C, compared with the specific capacity 200 mAh [Formula: see text] at 0.2 C of 5/5 LLO in LIB. Meanwhile, the cycle life of Li-O2 batteries under 100% depth of discharge increases from a few cycles to more than 20 cycles, attributed to the transition of Ni2+ to Ni4+ upon charging that promotes decomposition of reaction products Li2O2 and by-products Li2CO3. These results demonstrate that the hybrid Li-ion/Li-O2 battery is a powerful way for combining advantages of the intercalation and conversion-type cathodes, promising for construction of future high-energy batteries.