An Adsorption‐Insertion Mechanism of Potassium in Soft Carbon. Issue 4 (28th November 2021)

• Record Type: Journal Article
• Authors: Wu, Shijie; Song, Yan; Lu, Chunxiang; Yang, Tao; Yuan, Shuxia; Tian, Xiaodong; Liu, Zhanjun
• Is Part Of: Small. Volume 18:Issue 4(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-11-28
• Subjects: microstructures -- potassium storage mechanisms -- soft carbons; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202105275
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Soft carbon (SC) has become a promising anode for potassium ion batteries (PIBs) benefiting from its structural flexibility. However, the evolution of potassium storage behavior with the microstructure (the average size of the crystallites La and the average interlayer spacing a 3 ) is still unclear, which hinders the understanding of the potassium storage mechanism. Herein, a series of soft carbon with different microstructures is prepared through pyrolysis of petroleum pitch. Based on the analysis of the relationship between electrochemical behavior and microstructure, an adsorption‐insertion mechanism is proposed: the capacity in the voltage range of 0.45–1.1 V is originated from the adsorption of potassium ions on edge‐defect sites whereas the capacity below 0.45 V is attributed to the insertion of potassium ions into interlayers. When La equals to 10.56 Å, SCs exhibit an adsorption‐controlled mechanism. However, as La increases to 120.98 Å, the insertion process is dominant. With La increasing from 21.9 to 93.02 Å, SCs have two mixed behaviors. The initial insertion coefficients do not change until a 3 decreases to 3.46 Å. These findings highlight the relation of potassium storage behavior with different microstructures and the adsorption‐insertion mechanism can provide insights into the design of SC anodes for PIBs. Abstract : The relationship between the microstructure of petroleum pitch‐derived soft carbons and the electrochemical behaviors as anode in potassium ion batteries is investigated in this paper.