Identifying the Association between Surface Heterogeneity and Electrochemical Properties in Graphite

Abstract

Graphite materials for commercial Li-ion batteries usually undergo special treatment to control specific parameters such as particle size, shape, and surface area to have desirable electrochemical properties. Graphite surfaces can be classified into basal and edge planes in the aspect of the structure of carbons, with the existing defect sites such as functional groups and dislocations. The solid-electrolyte interphase (SEI) mostly forms at the edge plane and defect sites, as Li-ions only intercalate through these non-basal planes, whereas the electrochemical properties of graphite largely depend on its surface heterogeneity due to the difference of reactivity on each plane. In order to quantify the detailed surface structure of graphite materials, local-absorption isotherms were utilized, and the analyzed nanostructural parameters of various commercial graphite samples were correlated with the electrochemical properties of each graphite anode. Thereby, we have confirmed that the fraction of non-basal plane and fast-charging capability has strong linear relations. The pore/non-basal sites are also related to the cycle life by affecting the SEI formation, and the determination of surface heterogeneity and pores of graphite materials can provide powerful parameters that imply the electrochemical performances of commercial graphite.

Porous Metal Current Collectors for Alkali Metal Batteries

“…Exemplified with intercalation‐type anode materials, the commercial graphite electrode, the commonly used one, is composed of an ≈8 µm thick Cu foil with 100 µm thick graphite layers coated on both sides. [ 91 ] It can pair with different kinds of cathodes to achieve high energy densities. And when introducing the same thickness of Li foils on the thin Cu foil, it can theoretically match more cathode materials and achieve higher energy density due to the large specific capacity and low density of Li metal.…”

“…In a rechargeable alkali‐metal‐anode system, the uneven electric field and ion flux on planar conductive substrates will result in uncontrolled alkali metal deposition and even dendrite growth. [ 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 ] Therefore, rationally designing the current collector structure can help regulate the nucleation of alkali metal and control the morphology of deposited alkali metal. One of the most effective approaches is constructing a porous conductive substrate to dissipate the local current density and uneven ion flux, finally contributing to a homogeneous formation of alkali metal and obtaining a dendrite‐free alkali metal anode.…”

Rice husk-derived nano-SiO2assembled on reduced graphene oxide distributed on conductive flexible polyaniline frameworks towards high-performance lithium-ion batteries

“…5 Graphene is a one-atomthick carbon sheet that has generated considerable interest in energy storage applications due to its fascinating properties such as high electron mobility, excellent electrochemical stability, large surface area, and high mechanical strength. 6,7 However, there is a critical issue of graphene sheets aggregating during the electrode preparation process. 8 Thus, reduced graphene oxide (rGO) composites have been address to solve graphene sheets restacking problem.…”

Ultralight Porous Cu Nanowire Aerogels as Stable Hosts for High Li-Content Metal Anodes

“…To compete with the graphite anodes, porous Cu should theoretically have a porosity of 50% or more when the porous Cu current collector is compounded with Li to obtain the same thickness. Among the reported 3D Cu current collectors, Cu foam with a high porosity of ∼95% exhibits good potential in accommodating a large amount of Li loading. − However, the Cu foam current collector has too large pore size which is far from enough to suppress Li dendrites and achieve homogeneous Li deposition. The rigid structure shows poor mechanical performance that cannot accommodate the volume change during Li deposition/dissolution.…”