Orientation‐Dependent Intercalation Channels for Lithium and Sodium in Black Phosphorus

Abstract

can also accommodate foreign species in its interlayer spacing via intercalation, and it has been found that alkali metal intercalated BP can lead to the tunable bandgap [8] and also exhibit superconductivity. [9] Moreover, the capability to intercalate alkali metals can make BP a potential electrochemical reservoir for energy storage, similar to the graphite used for rechargeable ion batteries. The theoretical specific ion storage capacity for Li-ion batteries (LIBs) and Na-ion batteries (NIBs) can be as high as 2596 mAh g −1 , which is almost one order of magnitude higher than the commercial graphite-based materials (372 mAh g −1 ), holding great promise for future applications ranging from portable electronic devices to large-scale electrical vehicles and power tools. [10][11][12][13][14][15][16] Doubtless, BP intercalation compounds are of both scientific and technological importance in multiple critical fields, but the fundamental understanding of the underlying intercalation mechanism remains largely elusive. To bridge up this knowledge gap, we present an in situ investigation on the intercalation of BP with both lithium and sodium ions.The intercalation of alkali elements has been extensively studied in rechargeable battery systems, where the alkali ions can be intercalated into the host materials via electrochemical reactions. Specifically, a great effort has been devoted to the intercalation of lithium and sodium in a large variety of 2D materials, including graphite, [17,18] borophane, [19] transition metal dichalcogenides, [20][21][22][23] transition metal carbides/carbonitrides, [24,25] and tin-based compounds, [26][27][28] which have larger interlayer spacing bonded by vdW interaction to offer sufficient ionic transport pathway. Orthorhombic BP is the most thermodynamically stable structure compared to other two allotropes of white phosphorus and red phosphorus, [29,30] and has wide spacing between the 2D layers to allow the intercalation of Li and Na ions. Recently, the electrochemical intercalation behaviors of BP have been reported using in situ transmission electron microscopy (TEM) techniques. It is found that the alkali ions would intercalate into the layered host framework and then form alloying compounds with P with anisotropic volume expansion and amorphization, which has been verified in lithiation [31] and sodiation, [32] respectively. Besides, the sodium-ion transport was suggested to be anisotropic and could cause atomic stack reordering upon slight intercalation. [33,34] Although these early studies have depicted the changes in morphology and volume Black phosphorus (BP) with unique 2D structure enables the intercalation of foreign elements or molecules, which makes BP directly relevant to high-capacity rechargeable batteries and also opens a promising strategy for tunable electronic transport and superconductivity. However, the underlying intercalation mechanism is not fully understood. Here, a comparative investigation on the electrochemically driven intercalation of lithium and sodiu...

Reaction mechanism and structural evolution of fluorographite cathodes in Li/Na/K batteries

“…13 As the ionic radius of K, Na, and Li is 138 pm, 102 pm, and 76 pm, respectively, the discharge rate speci c capacity of Li-ion electrode materials is normally larger than that of Na-and Kion materials because of the higher mobility of Li + . 25,26 However, the inverse phenomenon of this electrochemical performance is observed, when using CF x as the cathode in KIBs, NIBs, and LIBs, probably due to the Strokes' radius and electrolyte-assisted reaction mechanism.…”

The development, application, and performance of black phosphorus in energy storage and conversion

“…The active BP electrode physically transferred on the TEM grid was connected with the movable Li counter electrode via a potentiostat to drive the electrochemical reactions within an in situ TEM holder. 67 It indicates that the lithium diffusion along the zigzag direction is energetically preferable, while the diffusion along the armchair direction confronts an increased energy barrier, which might lead to an orientation-dependent intercalation channels. These findings Please do not adjust margins Please do not adjust margins provide insights into the fundamental mechanism of lithiation in BP.…”

“…(d) Schematics of in situ TEM setup of the half-cell battery. Reproduced with permission 67. Copyright 2019, Wiley.…”

Novel two-dimensional monoelemental and ternary materials: growth, physics and application

“…The asobtained BiOCl platelets exhibit high performance of photodetection to 266-nm laser with responsivity up to ~8 A · W −1 and fast response speed of ~18 ps. The BiOCl-TiO 2 heterojunctions were also explored as ultraviolet PDs performing ultrahigh on/off ratio (up to 2.2 × 10 5 ), responsivity of 41.94 A · W −1 and detectivity (D * ) of 1.41 × 10 14 Jones, as well as a high linear dynamic range of 103.59 dB [189]. Overall, the favorable band structures, facile CVD growth and high stability suggest that 2D BiOX can be a promising material for future optoelectronic applications.…”

“…Recently, a new cousin of graphene, called "plumbene," which has the famous Weaire-Phelan bubble structure, has been considered to bring a new boom in the post-Moore law period [11]. Since 2014, similar with Gr, composed of a single element with an atomic thickness profile, black phosphorus (BP), as a star monoelemental material with a tunable bandgap (0.3-2.0 eV) [12], low grain boundary and high carrier mobility (10 3 cm 2 · V −1 · s −1 ) [13], has been applied in anisotropic lithium and sodium intercalation [14], (opto) electronic devices [15][16][17], sensors, medical treatment and energy [18]. However, excellent BP devices have to be covered or sandwiched by hexagonal-nitrile boron (h-BN) due to their poor air stability [19].…”