Unraveling the Effect of Intrinsic Carbon Defects on Potassium Storage Performance

Abstract

Defects engineering is an attractive strategy to improve the potassium storage performance of carbon anodes. The current studies mainly focus on the introduction of external defects via heteroatom doping, however, the exploration on the effect of intrinsic defects caused by the loss of atoms or distortion in the crystal lattice on potassium storage is still lacking to date. Hence, a series of carbon materials with different intrinsic defect levels are developed via a soft-template assisted method. It is found that intrinsic defects content in carbon is synergistically determined by the application of template and pyrolysis temperature, and a higher defects content is more likely to expose enormous edge active sites. This greatly promotes K-adsorption storage during surface-induced capacitive process, and therefore a strong positive correlation between capacity/capacity retention and intrinsic defects content is confirmed. As a result, the electrode with maximum defects content realizes a good capacity and a rate capability with long cycle lifespan (225.9 mAh g −1 at 2 A g −1 over 2000 cycles). This study offers an insight into the role of intrinsic defects of carbon materials in potassium storage performance.

Defect engineering in carbon materials for electrochemical energy storage and catalytic conversion

“…Wang et al synthesized carbon materials with different intrinsic defects by a template-assisted method and investigated the effect of intrinsic defects on the potassium storage performance. 53 It was found that higher levels of has a stronger attraction to K than N site (Fig. 7d).…”

“…Wang et al synthesized carbon materials with different intrinsic defects using a template-assisted method and investigated the effect of intrinsic defects on the potassium storage performance. 53 It was found that higher levels of intrinsic defects were more beneficial to improve the capacitive behavior by providing sufficient potassium adsorption sites. The researchers revealed a strong positive correlation between the level of intrinsic defects and the capacity/capacity retention, while the wettability of the carbon materials increased with the increase of the defect concentration, resulting in the rapid penetration of electrolyte ions.…”

“…Figure 2. Outline of the history of carbon defect engineering in the field of electrochemical energy storage and catalytic conversion 12,[46][47][48][49][50][51][52][53][54][55][56][57]. …”

Rationally Tailoring Superstructured Hexahedron Composed of Defective Graphitic Nanosheets and Macropores: Realizing Durable and Fast Potassium Storage

“…This result reveals that the obtained C content by XPS is relatively higher than that in the whole carbon matrix, in accordance with the previously reported works. [ 4 , 5 ] Moreover, the detected O is supposed to improve the wettability of electrode materials and increase the utilization ratio of active surface, [ 10 , 13 ] thus favoring a good rate and capacity. As displayed in Figure 3d–f , the high resolution XPS spectrum of C 1s can be deconvoluted into three peaks at 284.7, 285.6, and 286.4 eV, [ 27 , 28 ] corresponding to sp2 C, sp3 C, and C−O, respectively.…”

“…Among all the anodes, carbonaceous materials are highly preferable and have been extensively investigated because of their excellent electrical conductivity and chemical stability. [ 9 , 10 , 11 ] Nevertheless, K‐ions with a larger size (1.38 Å for K + versus 0.76 Å for Li + ) can induce more distinct volume variation of the host electrode and sluggish kinetics for solid‐state diffusion during intercalation/de‐intercalation process, [ 12 , 13 , 14 ] eventually leading to serious capacity decay and inferior rate. Defect engineering in carbon matrix has been proven to be an effective strategy to resolve these issues, and simultaneously contributes to breaking through theoretical capacity to a large extent.…”