Abstract
A Li_(0.27)K_(0.72)Ni_(0.6)Co_(0.2)Mn_(0.2)O_2 (LKNCM) cathode for potassium-ion batteries (PIBs) was obtained from LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 (NCM622) via ion exchange. In-situ X-ray diffraction and high-resolution transmission electron microscopy analyses showed the morphological and structural changes that occur during K~+-ion insertion. Particularly, the primary particles became porous, and the (003) interlayer distance expanded from 4.76 to 6.50 A, providing a potassiation/depotassiation framework. Inductively coupled plasma-optical emission spectroscopy revealed that 0.72 mol of K~+ ions were inserted into the Li-extracted NCM622 cathode per formula unit, indicating that the amounts of extracted Li~+ and inserted K~+ were similar. The developed LKNCM cathode exhibited a theoretical capacity of 160.79 mAh g~(-1) and an initial discharge capacity of 106.95 mAh g~(-1) with an average potential of 3.1 V vs. K/K~+. These results demonstrate that ion exchange enables layered NCM cathodes for lithium-ion batteries to be applied as cathodes for PIBs.
NSTL
Elsevier