Abstract
Regulating material properties by accurately designing its structure has always been a research hotspot. In this study, by a simple and eco-friendly mechanical ball milling, we could successfully engineer the defect degree of the graphite. Moreover, according to the accurate deconstruction of the structure by atomic pair distribution function analysis (PDF) and X-ray absorption near-edge structure analysis (XANES), those structural defects of the ball-milled graphite (BMG) mainly exist as carbon atom vacancies within the graphene structure, which are beneficial to enhance the lithium and sodium storage performance of BMG. Therefore, BMG-30 h exhibits superior lithium and sodium storage performance.
Highlights
The ball-milled graphite (BMG) electrode was assembled as CR2032 coin-type cells in a glove box lled with Ar atmosphere, Mechanical ball milling is chosen for manufacturing defects in graphite due to its facile control and eco-friendly nature
As the ball milling time increased to 10 h, as shown in Fig. 1c, the major morphology of BMG-10 h was particles with a particle size of about 200 nm, due to the cutting and crumpling by mechanical ball milling
The morphology of BMG-30 h demonstrated in Fig. 1d is similar to that of BMG-10 h but with smaller particle sizes
Summary
They expanded the graphite interlayer distance up to 4.3 nm and achieved a capacity of 280 mA h gÀ1 at the current density of 20 mA gÀ1 These results are encouraging; it is worthy to note that there are still some drawbacks among both the methods.[28,29,30,31,32,33,34] For the Na-solvent co-intercalation approach, (the inserted solvents caused a high-level of volume change) the high-level volume caused by the solvent cointercalation and the relatively low capacity (below 150 mA h gÀ1) inherently limit its practical applications. The intercalation pseudocapacitive charge storage mechanism is a promising method to achieve high capacity, superior rate performance, and long life cycle stability, which have been demonstrated by Dunn et al.[35]. We demonstrate that the superior sodium storage performance of BMGs come from the contribution of intercalation pseudocapacitance
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