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Microstructure‐Dependent K + Storage in Porous Hard Carbon
Author(s) -
Li Weize,
Zhang Rui,
Chen Zhen,
Fan Binbin,
Xiao Kuikui,
Liu Hui,
Gao Peng,
Wu Jianfang,
Tu Chuanjun,
Liu Jilei
Publication year - 2021
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.202100397
Subject(s) - materials science , electrolyte , mesoporous material , intercalation (chemistry) , chemical engineering , microstructure , electrochemistry , dielectric spectroscopy , pseudocapacitor , anode , energy storage , nanotechnology , carbon fibers , porosity , supercapacitor , composite number , inorganic chemistry , electrode , chemistry , composite material , organic chemistry , catalysis , power (physics) , physics , quantum mechanics , engineering
Abstract Hard carbons (HCs) are emerging as promising anodes for potassium‐ion batteries (PIBs) due to overwhelming advantages including cost effectiveness and outstanding physicochemical properties. However, the fundamental K + storage mechanism in HCs and the key structural parameters that determining K + storage behaviors remain unclear and require further exploration. Herein, HC materials with controllable micro/mesopore structures are first synthesized by template‐assisted spray pyrolysis technology. Detailed experimental analyses including in situ Raman and in situ electrochemical impedance spectroscopy analysis reveal two different K + storage ways in the porous hard carbon (p‐HC), e.g., the adsorption mechanism at high potential region and the intercalation mechanism at low potential region. Both are strongly dependent on the evolution of microstructure and significantly affect the electrochemical performance. Specifically, the adequate micropores act as the active sites for efficient K + storage and ion‐buffering reservoir to relieve the volume expansion, ensuring enhanced specific capacity and good structural stability. The abundant mesopores in the porous structure provide conductive pathways for ion diffusion and/or electrolyte infiltration, endowing fast ionic/electronic transport kinetics. All these together contribute to the high energy density of activated carbon//p‐HCs potassium ion hybrid capacitors (74.5 Wh kg −1 , at 184.4 W kg −1 ).