Enhancing charge storage of O-doped perovskite fluorides via in-situ electrochemical oxidation for high-performance potassium-ion capacitors  

作　　者：Jing Zhao Zicheng Cai Yue Fan Yunan Wang Yu Song Jie Liu Shuangwen Li Di Guo Xiaoxia Liu 

机构地区：[1]Department of Chemistry,Northeastern University,Shenyang 110819,China [2]School of Resources and Civil Engineering,Northeastern University,Shenyang 110819,China [3]National-local Joint Engineering Research Center of High-efficient Exploitation Technology for Refractory Iron Ore Resources,Shenyang 110819,China [4]School of Materials Engineering,North China Institute of Aerospace Engineering,Langfang 065000,China

出　　处：《Journal of Materials Science & Technology》2023年第27期111-120,共10页材料科学技术（英文版）

基　　金：the financial support from Liaoning Sci-ence and Technology Development Foundation Guided by Cen-tral Government(No.2021JH6/10500139);the Fundamental Research Funds for the Central Universities(No.N2205003);the financial support from the National Natural Science Foundation of China(No.52003007);Nat-ural Science Foundation of Hebei Province(No.E2019409063);Langfang top-notch talent(No.LFBJ202004).

摘　　要：Potassium ion capacitors(PICs)are regarded as promising large-scale aqueous energy storage systems.However,due to the poor K^(+)transport kinetics and the structural instability of the cathode materials,the key issues of limited energy density and poor cyclic stability are obstacles to the in-depth growth of PICs.Herein,a novel O-doped perovskite fluoride is demonstrated via an in-situ electrochemical oxidation strategy as the cathode for PICs,introducing additional defects that improve the capacitance and facilitate the reaction kinetics of the electrode.During the electrochemical oxidation process,it is discovered that the perovskite fluoride crystal tends to transform into disordered O-doped KMnF 3(K_(x)MnF_(y)O_(z)),realizing a structural reconstruction at the electrode material/electrolyte interface.The First-principles calculations based on density functional theory(DFT)are performed to confirm that the improved electrical conduc-tivity and low ionic adsorption energy may be ascribed to the substitution of oxygen for fluorine.The obtained K_(1.14)MnF_(1.17)O_(1.26) cathode achieves a high specific capacitance of 694 F g^(-1) at 1 A g^(-1),as well as high capacitance retention of 91.3%after 10,000 charge/discharge cycles in mild K_(2)SO_(4) electrolyte.This study provides an effective strategy to improve the capacitive performance of perovskite fluoride cathode materials in electrochemical energy storage.

关 键 词：Perovskite fluorides O-doped Potassium-ion capacitors Charge storage mechanism 

分 类 号：O643.36[理学—物理化学] TM911.4[理学—化学]