Scallop‐Inspired Shell Engineering of Microparticles for Stable and High Volumetric Capacity Battery Anodes

Abstract

Building stable and efficient electron and ion transport pathways are critically important for energy storage electrode materials and systems. Herein, a scallop-inspired shell engineering strategy is proposed and demonstrated to confine high volume change silicon microparticles toward the construction of stable and high volumetric capacity binder-free lithium battery anodes. As for each silicon microparticle, the methodology involves an inner sealed but adaptable overlapped graphene shell, and an outer open hollow shell consisting of interconnected reduced graphene oxide, mimicking the scallop structure. The inner closed shell enables simultaneous stabilization of the interfaces of silicon with both carbon and electrolyte, substantially facilitates efficient and rapid transport of both electrons and lithium ions from/to silicon, the outer open hollow shell creates stable and robust transport paths of both electrons and lithium ions throughout the electrode without any sophisticated additives. The resultant self-supported electrode has achieved stable cycling with rapidly increased coulombic efficiency in the early stage, superior rate capability, and remarkably high volumetric capacity upon a facile pressing process. The rational design and engineering of graphene shells of the silicon microparticles developed can provide guidance for the development of a wide range of other high capacity but large volume change electrochemically active materials.

Dimensionally Designed Carbon–Silicon Hybrids for Lithium Storage

“…Third, the new deposition of solid electrolyte interphase (SEI) on the freshly exposed Si surface during repetitive volume expansion/contraction leads to an increasingly thicker SEI layer, in which the electrically insulating nature of the SEI degrades the electrical contact between active materials and conductive additives or current collectors, as well as prolongs the lithium ion diffusion distance through the thick SEI. Targeting these problems facing Si, combining silicon and carbon at the nanometer scale in a rational, controllable, and tailorable manner, to construct carbon–silicon hybrids with well‐defined structures, tailored interfaces, and newly featured properties, has been proven to be a powerful way to confer enhanced electrochemical lithium storage performance . Specifically, the design and construction of carbon–silicon hybrids from the viewpoint of dimensionalities represent a new dimension for the exploitation of silicon anodes, in which x ‐dimensional (e.g., 0D, 1D, 2D) silicon enables optimized lithium ion diffusion and transport, x ‐dimensional (e.g., 0D, 1D, 2D) carbon confers enhanced electron transport, and dimensional hybridization renders the void involvement for accommodating the volume change of Si (Figure b).…”

“…Very recently, Zhang et al proposed a scallop‐inspired shell engineering strategy to develop a stable and high volumetric capacity binder‐free lithium battery anode, where each silicon microparticle was sealed in an inner adaptable overlapped graphene shell and an outer open hollow shell consisting of interconnected reduced graphene oxide ( Figure a) . The inner closed shell simultaneously stabilized the interfaces of silicon with both carbon and electrolyte and substantially facilitated efficient and rapid electron and lithium ion transport, while the outer open hollow shell created stable and robust transport paths of both electrons and lithium ions throughout the electrode without any sophisticated additives.…”

“…a) Fabrication process and electrode design, b) SEM image, c) TEM image, d) cycling performance, e) electrode density versus pressing pressure plots, and f) rate capabilities. Reproduced with permission . Copyright 2018, Wiley‐VCH.…”

Engineering Carbon Distribution in Silicon‐Based Anodes at Multiple Scales

“…[45] It should be pointed out that the introduction of void space will raise new problemss uch as low tap density and volumetric capacity. [48] In addition, other hierarchical structures such as granadilla-like [22] and scallop-inspired [49] superstructures with yolk-shell nanocomposites as primary particles have been engineered. [47] Of notable success are the pomegranate-inspired carbon/silicon-based anodes, which can achieve high stable cycling even when the areal capacity was increased to the level of commercial LIBs.…”

Facile and Scalable Synthesis of Si@void@C Embedded in Interconnected 3D Porous Carbon Architecture for High Performance Lithium‐Ion Batteries

“…Another effective strategy is to coat Si with oxides [ 12 ] metals [ 13 ] and conducting carbonaceous, [ 14 ] which can minimize the destruction of the electrode architecture by the volume change of individual particles as well as render a stable SEI on the surface of individual material particles thereby restraining the degradation of electron/lithium ion transport paths from/ to silicon. [ 15 ] Especially Si/C nanohybrids, the conducting carbonaceous and porous hollow nanostructure can enhance the transmission speed for electron and shorten the diffusion distance of Li + . Therefore, hybridizing silicon nanoparticles with void space and porous carbon nanomaterials, can improve the conductivity and make the best of the void space to alleviate the volume stress during the initial lithiation process.…”