Modification for Improving the Electrochemical Performance of Spherically-Shaped Natural Graphite as Anode Material for Lithium-Ion Batteries

Abstract

A modified spherically-shaped natural graphite (M-SNG) material is prepared, and its physical and electrochemical properties for use as an anode material in lithium-ion batteries are reported. M-SNG is obtained by ultrasonication in a carbon precursor solution, followed by heat-treatment at 1,200°C under argon atmosphere. A gap between the flaky NG fragments forms on the surface and inside the M-SNG particles; amorphous carbon is present in this gap and on the M-SNG particle surface. The M-SNG anode exhibits superior electrochemical performance compared to a commercial carbon-coated SNG (C-SNG) anode, with high charge/discharge rate capability and stable capacity retention. The enhanced charge/discharge rate capability is attributed to the good soaking ability of the M-SNG anode, which allows the electrode to maintain low polarization even at high current density. The amorphous carbon coating on the surface and inside of the M-SNG suppresses side reactions with the electrolyte during charge–discharge cycles, facilitating excellent cycling stability, good thermal stability, and adequate dimensional stability.

An Analysis of Artificial and Natural Graphite in Lithium Ion Pouch Cells Using Ultra-High Precision Coulometry, Isothermal Microcalorimetry, Gas Evolution, Long Term Cycling and Pressure Measurements

“…NG is known to perform poorly in some cells, which has in the past been attributed to surface exfoliation and cracking of particles. [4][5][6][7] Park et al found spherical natural graphite showed signs of particle swelling and cracking caused by mechanical strain during cycling, which could be suppressed using a carbon coating process. 5 Carbon coatings on natural graphite negative electrodes have been studied in the past to avoid exfoliation from propylene carbonatecontaining electrolytes, but these coatings may decrease the energy density.…”

“…[4][5][6][7] Park et al found spherical natural graphite showed signs of particle swelling and cracking caused by mechanical strain during cycling, which could be suppressed using a carbon coating process. 5 Carbon coatings on natural graphite negative electrodes have been studied in the past to avoid exfoliation from propylene carbonatecontaining electrolytes, but these coatings may decrease the energy density. 4,6 AG performance reported in the literature appears to outperform natural graphite, however, few direct comparisons of artificial and natural graphite exist in the literature.…”

High Performance of a Polydopamine-Coated Graphite Anode with a Stable SEI Layer

“…The SEI layer tends to form mostly during the first cycle, being largely dependent on the specific surface area of the active material [for graphite and G–PD (20 min), specific surface areas are shown in Table S1]. , Therefore, it seems that similar amounts of the SEI layer were generated on all electrodes. However, an irreversible reaction between PD and Li occurred.…”

Materials by Design: Tailored Morphology and Structures of Carbon Anodes for Enhanced Battery Safety

“…For example, polymeric coating of graphite anode enhanced the cycling stability and decreased the first cycle capacity loss by mitigating electrolyte decomposition at the electrode surface . However, such “add-on solutions” often compromise the primary battery function, i.e., electrochemical energy storage. − …”