A N–CoSe/CoSe <sub>2</sub> –C@Cu hierarchical architecture as a current collector‐integrated anode for potassium‐ion batteries
Zijie Mu, Yanjun Gao, Wen‐Shuai Dong, Zongyou Li, Qingyi Song, Hanjiao Huang, Lidong Xing, Jianguo Zhang, Wei Wang, Qiyao Yu
Abstract
Abstract The highly reversible insertion/extraction of large‐radius K + into electrode materials remains a tough goal, especially for conversion‐type materials. Herein, we design a current collector‐integrated electrode (N–CoSe/CoSe 2 –C@Cu) as an advanced anode for potassium‐ion battery (PIBs). The conductive CoSe/CoSe 2 heterojunction with rich Se vacancy defects, conductive sp 2 N‐doped carbon layer, and the elastic copper foil matrix can greatly accelerate the electron transfer and enhance the structural stability. Consequently, the well‐designed N–CoSe/CoSe 2 –C@Cu current collector‐integrated electrode displays enhanced potassium storage performance with regard to a high capacity (325.1 mAh·g −1 at 0.1 A·g −1 after 200 cycles), an exceptional rate capability (223.5 mAh·g −1 at 2000 mA·g −1 ), and an extraordinary long‐term cycle stability (a capacity fading of only 0.019% per cycle over 1200 cycles at 2000 mA·g −1 ). Impressively, ex situ scanning electron microscopy (SEM) characterizations prove that the elastic structure of copper foil is merged into the cleverly designed N–CoSe/CoSe 2 –C@Cu heterostructure, which buffers the deformation of structure and volume and greatly promotes the cycle life during the potassium/depotassium process.