High Pseudocapacitance‐Driven CoC<sub>2</sub>O<sub>4</sub> Electrodes Exhibiting Superior Electrochemical Kinetics and Reversible Capacities for Lithium‐Ion and Lithium–Sulfur Batteries
Zhiming Zhou, Peirong Lin, Shiqiang Zhao, Huile Jin, Yudan Qian, an Chen Xi, Xinyue Tang, Qingcheng Zhang, Daying Guo, Shun Wang
Abstract
Abstract In this study, cuboid‐like anhydrous CoC 2 O 4 particles (CoC 2 O 4 ‐HK) are synthesized through a potassium citrate‐assisted hydrothermal method, which possess well‐crystallized structure for fast Li + transportation and efficient Li + intercalation pseudocapacitive behaviors. When being used in lithium‐ion batteries, the as‐prepared CoC 2 O 4 ‐HK delivers a high reversible capacity (≈1360 mAh g ‐1 at 0.1 A g ‐1 ), good rate capability (≈650 mAh g ‐1 at 5 A g ‐1 ) and outstanding cycling stability (835 mAh g ‐1 after 1000 cycles at 1 A g ‐1 ). Characterizations illustrate that the Li + ‐intercalation pseudocapacitance dominates the charge storage of CoC 2 O 4 ‐HK electrode, together with the reversible reaction of CoC 2 O 4 +2Li + +2e − →Co+Li 2 C 2 O 4 on discharging and charging. In addition, CoC 2 O 4 ‐HK particles are also used together with carbon–sulfur composite materials as the electrocatalysts for lithium–sulfur (Li–S) battery, which displays a gratifying sulfur electrochemistry with a high reversibility of 1021.5 mAh g −1 at 2 C and a low decay rate of 0.079% per cycle after 500 cycles. The density functional theory (DFT) calculations show that CoC 2 O 4 /C can regulate the adsorption‐activation of reaction intermediates and therefore boost the catalytic conversion of polysulfides. Therefore, this work presents a new prospect of applying CoC 2 O 4 as the high‐performance electrode materials for rechargeable Li‐ion and Li–S batteries.