Fast and Long‐Lasting Potassium‐Ion Storage Enabled by Rationally Engineering Strain‐Relaxation Bi/Bi<sub>2</sub>O<sub>3</sub> Nanodots Embedded in Carbon Sheets
Xi Liu, Zhefei Sun, Yingjuan Sun, Haoxiang Lin, Zhisong Chen, Xiaoxuan Chen, Li Niu, Qiaobao Zhang, Hongyan Li
Abstract
Abstract Bismuth (Bi)‐based materials merit high theoretical volumetric specific capacity (3800 mAh mL⁻ 1 ) but suffer from huge volume variations and sluggish reaction kinetics during cycling. Herein, the optimal framework of Bi/Bi 2 O 3 nanodots enriched in suitable outer amorphous carbon sheets (Bi/Bi 2 O 3 NDs@CSs) is first proposed to alleviate volume variations and accelerate stable charge transport to boost K + storage performance. The introduction of proper Bi 2 O 3 not only provides an efficient K + adsorption path, but also effectively buffers volume changes via conversion reaction. Accordingly, the as‐prepared anode exhibits a remarkable rate capability (149.3 mAh g −1 at 60 A g −1 , 42% capacity retention with a 120‐fold current‐density increase) and extraordinary durability (1800 cycles at 5.0 A g −1 , 95% capacity retention), among the best rate and cycling performance to date in potassium ion batteries (PIBs) anodes. Theoretical calculations reveal the feasible structures of Bi/Bi 2 O 3 NDs@CSs with double protection of carbon sheets and Bi 2 O 3 are conducive to enhance charge transfer and efficiency of electrochemical reaction. Substantial in situ / ex situ characterizations and finite element simulation further unveil high reversibility and robust mechanical behavior of Bi/Bi 2 O 3 NDs@CSs, favorable for the reinforcement of structural stability. This study provides new insights into developing high‐performance and durable Bi‐based anodes for PIBs.