Potassium-ion storage behavior of microstructure-engineered hard carbons

Kim, Hoseong; Hyun, Jong Chan; Jung, Ji In; Lee, Jin Bae; Choi, Jaewon; Cho, Se Youn; Jin, Hyoung‐Joon; Yun, Young Soo

doi:10.1039/d1ta08981a

Cited by 14 publications

(9 citation statements)

References 65 publications

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“…Stage I intercalation compounds are known to have a golden color, whereas the stage II, III, and IV intercalation compounds exhibit a blue color. [30][31][32] The fully lithiated hard carbon electrodes reveal that the black-colored pristine electrode transforms into dark blue colors for HC1200, HC1600, HC2000, and HC2400, and dark yellow color for HC2800 (Figure S21a-e, Supporting Information). The color change indicates that lithium-ion intercalation reaction happens in all the samples, where lithium intercalation compounds of stage II, III, and IV were formed for HC1200, HC1600, HC2000, and HC2400, whereas a stage I intercalation compound is mainly formed for HC2800.…”

Section: Resultsmentioning

confidence: 99%

Revisiting Lithium‐ and Sodium‐Ion Storage in Hard Carbon Anodes

et al. 2023

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The galvanostatic lithiation/sodiation voltage profiles of hard carbon anodes are simple, with a sloping drop followed by a plateau. However, a precise understanding of the corresponding redox sites and storage mechanisms is still elusive, which hinders further development in commercial applications. Here, a comprehensive comparison of the lithium‐ and sodium‐ion storage behaviors of hard carbon is conducted, yielding the following key findings: 1) the sloping voltage section is presented by the lithium‐ion intercalation in the graphitic lattices of hard carbons, whereas it mainly arises from the chemisorption of sodium ions on their inner surfaces constituting closed pores, even if the graphitic lattices are unoccupied; 2) the redox sites for the plateau capacities are the same as those for the closed pores regardless of the alkali ions; 3) the sodiation plateau capacities are mostly determined by the volume of the available closed pore, whereas the lithiation plateau capacities are primarily affected by the intercalation propensity; and 4) the intercalation preference and the plateau capacity have an inverse correlation. These findings from extensive characterizations and theoretical investigations provide a relatively clear elucidation of the electrochemical footprint of hard carbon anodes in relation to the redox mechanisms and storage sites for lithium and sodium ions, thereby providing a more rational design strategy for constructing better hard carbon anodes.

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Section: Resultsmentioning

confidence: 99%

Revisiting Lithium‐ and Sodium‐Ion Storage in Hard Carbon Anodes

et al. 2023

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“…Kim and coworkers investigated the correlation between microstructure and potassium-ions storage behavior in hard carbons. [13] They concluded that a few nanometer-sized graphitic domains and expanded d-spacing (>3.5 Å) in disordered graphitic structures can trigger fast and stable potassium-ion intercalation. Similarly, Alvin et al established the relationship between the intercalation sites and low-potential-plateau capacity.…”

Section: Introductionmentioning

confidence: 99%

“…Hard carbon materials with local graphitic nanodomains are mainly synthesized by controlling carbonization temperature, while high temperature would induce the closed domains that are inaccessible for K + (de)intercalation. [ 10b,11e,13 ] Thus, an effective approach is expected to fabricate hard carbon materials with a crystalline structure of short‐range order and large interlayer spacing.…”

Section: Introductionmentioning

confidence: 99%

Engineering of the Crystalline Lattice of Hard Carbon Anodes Toward Practical Potassium‐Ion Batteries

Zhong

Zhang

Sun

et al. 2022

Adv Funct Materials

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Hard carbons have attracted increased interest as an alternative of graphite for the anodes of potassium-ion batteries (PIBs). However, the practical applications of hard carbon anodes are hampered by their low capacities, high potential platforms, and large potential hysteresis. Hard carbons coupled with graphitic nanodomains can achieve stable potassium-ion storage behaviors with low potential platforms and low potential hysteresis. Herein, the crystalline lattice in hard carbon anodes is tuned by incorporating graphene oxide in renewable lignin precursors. The modified hard carbon (i.e., QLGC) anodes show graphitized nanodomains in the carbon matrix with an expanded interlayer spacing (0.42 nm) in the amorphous regions, which results in a stable potassium-ion (de)intercalation behavior. Thus, the QLGC anodes exhibit a high capacity of 164 mAh g −1 with low potential hysteresis in the low potential platform region. Moreover, the QLGC anode delivered a highly stabilized capacity of 283 mAh g −1 at 50 mA g −1 , a high-rate capability, and stable cycling performance. Furthermore, the charge storage mechanisms of QLGC anode are elucidated by electro-kinetic analysis and ex/in situ physicochemical characterizations. This study opens a new avenue for designing hard carbon anodes with engineered crystalline lattices toward practical PIBs.

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“…Some studies have shown that stable GICs may not be formed, and the GICs are directly related to the degree of graphitization of hard carbon materials. 71 In the trace of highly graphitized sample (DGC-2000), significant formation of KC 8 (stage I) was observed at the end of complete potassiation. Surprisingly, two-phase intercalation products, KC 48 (stage IV), KC 36 (Stage III) and KC 24 (Stage II), were separated using the in situ XRD pattern signal during the electrochemical cycle of DGC-2800 (Fig.…”

Section: Intercalation Mechanismmentioning

confidence: 95%

“…Correspondingly, the intercalation mechanism often presents a voltage plateau in the low voltage range, providing most of the capacity and a lower average voltage. 71,76,77 The storage mechanism is closely bound up with the micro-nano structure of the hard carbon anodes themselves. As displayed in Fig.…”

Section: Adsorption Mechanismmentioning

confidence: 99%