Superior Low-Temperature Power and Cycle Performances of Na-Ion Battery over Li-Ion Battery

[Image: see text] The most simple and clear advantage of Na-ion batteries (NIBs) over Li-ion batteries (LIBs) is the natural abundance of Na, which allows inexpensive production of NIBs for large-scale applications. However, although strenuous research efforts have been devoted to NIBs particularly since 2010, certain other advantages of NIBs have been largely overlooked, for example, their low-temperature power and cycle performances. Herein, we present a comparative study of spirally wound full-cells consisting of Li(0.1)Na(0.7)Co(0.5)Mn(0.5)O(2) (or Li(0.8)Co(0.5)Mn(0.5)O(2)) and hard carbon and report that the power of NIB at −30 °C is ∼21% higher than that of LIB. Moreover, the capacity retention in cycle testing at 0 °C is ∼53% for NIB but only ∼29% for LIB. Raman spectroscopy and density functional theory calculations revealed that the superior performance of NIB is due to the relatively weak interaction between Na(+) ions and aprotic polar solvents.