Title
Link between Alkali Metals in Salt Templates and in Electrolytes for Improved Carbon-Based Electrochemical Capacitors
Authors
[ 1 ] Instytut Chemii i Elektrochemii Technicznej, Wydział Technologii Chemicznej, Politechnika Poznańska | [ P ] employee
Scientific discipline (Law 2.0)
Year of publication
2021
Published in
Article type
scientific article
Publication language
english
Keywords
EN
- templated carbon
- soft-salt template
- electrochemical capacitor
- aqueous electrolyte
- cation match
Abstract
EN Various alkali metal (Li+, Na+, K+, Rb+, and Cs+) chlorides with Pluronic F127 were used as a soft-salt template for tuning the textural and structural properties of carbon. Highly conductive metal hydroxide solutions, where the cations are the same as those in the salt template, have been used as electrolytes. By increasing the size of the cation in the template, the textural properties of carbon, such as the specific surface area, micropore volume, and pore size, were remarkably enhanced. It directly translates to an increase in the specific capacitance of the electrode material. For a constant current charge/discharge at 0.1 A g–1, the electrode composed of LiCl-T and operating with 1 mol L–1 LiOH demonstrates the capacitance of 124 F g–1, whereas CsCl-T with the same electrolyte has a capacitance of 216 F g–1. Moreover, the materials show the highest capacitance retention (up to 75%) vs. the current regime applied when the cation used during synthesis matches the cation present in the electrolyte (i.e., LiCl-T with LiOH). Interestingly, capacitance normalized by specific surface area has been found to be the highest when LiOH solution is applied as an electrolyte. Thus, for this metric, the size of ions seems to be a crucial parameter. The importance of mesoporosity is highlighted as well by using materials with a similar fraction of micropores and with or without mesopores. Briefly, the presence of mesopore fraction proved to be essential for improved capacity retention (69% vs. 30%). Besides textural properties, the graphitization degree impacts the electrochemical performance as well. It increases among the samples, in accordance with cation-π binding energy, e.g., LiCl-T is the most “graphitic-like” material and CsCl-T is the most disordered. Thus, the more graphitic-like materials demonstrate higher rate capability and cycle stability.
Date of online publication
08.01.2021
Pages (from - to)
2584 - 2599
License type
CC BY-NC-ND (attribution - noncommercial - no derivatives)
Open Access Mode
czasopismo hybrydowe
Open Access Text Version
final published version
Full text of article
Access level to full text
public
Ministry points / journal
200
Ministry points / journal in years 2017-2021
200
Impact Factor
10,383
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