Perovskite fluoride NaNiF <sub>3</sub> with hollow micron sphere structure as anode for Li‐ion hybrid capacitors
Ai‐Jun Jiao, Jian‐Fei Gao, Zheng‐Hua He, Jing‐Feng Hou, Ling‐Bin Kong
Abstract
Abstract Lithium‐ion hybrid capacitors (LIHCs) are gaining more attention and applications because they break the performance limitations of supercapacitors (SCs) and lithium‐ion batteries (LIBs). However, the difference of energy storage mechanism between anode and cathode is a problem that must be faced by Li‐ion hybrid capacitors. The selection of suitable anode and cathode materials is one of the effective ways to solve this problem. Here, we synthesized hollow spherical perovskite fluoride NaNiF 3 by a simple and safe method. The specific capacity of NaNiF 3 is 142 mAh·g −1 at 0.1 A·g −1 for 1000 cycles. The mechanism in the cycling of NaNiF 3 electrodes was investigated using ex situ X‐ray photoelectron spectroscopy (XPS), which is typical of the conversion reaction. Meanwhile, the NaNiF 3 //activated carbon (AC) Li‐ion hybrid capacitor assembled and showed better energy density (69 Wh·kg −1 ) and power density (5699 W·kg −1 ). Its capacity retention after long cycling was 79%. The use of NaNiF 3 expands the choice of electrode materials for LIHCs and extends their practical applications.