An Air‐Stable Densely Packed Phosphorene–Graphene Composite Toward Advanced Lithium Storage Properties

Abstract

Phosphorene, monolayer or few‐layer black phosphorus (BP), has recently triggered strong scientific interest for lithium/sodium ion batteries (LIBs/SIBs) applications. However, there are still challenges regarding large‐scale fabrication, poor air stability. Herein, we report the high‐yield synthesis of phosphorene with good crystallinity and tunable size distributions via liquid‐phase exfoliation of bulk BP in formamide. Afterwards, a densely packed phosphorene–graphene composite (PG‐SPS, a packing density of 0.6 g cm−3) is prepared by a simple and easily up‐scalable spark plasma sintering (SPS) process. When working as anode materials of LIBs, PG‐SPS exhibit much improved first‐cycle Coloumbic efficiency (60.2%) compared to phosphorene (11.5%) and loosely stacked phosphorene–graphene composite (34.3%), high specific capacity (1306.7 mAh g−1) and volumetric capacity (256.4 mAh cm−3), good rate capabilities (e.g., 415.0 mAh g−1 at 10 A g−1) as well as outstanding long‐term cycling life (91.9% retention after 800 cycles at 10 A g−1). Importantly, excellent air stability of PG‐SPS over the 60 days observation in maintaining its high Li storage properties can be achieved. On the contrary, 95.2% of BP in PG sample was oxidized after only 10 days exposure to ambience, leading to severe degradation of electrochemical properties.

Alloy‐Based Anode Materials toward Advanced Sodium‐Ion Batteries

“…[184] They found that a reversible conversion from c-Si to a-Si occurs during the initial discharge process, which results in Na + rever sibly inserting into the newly generated a-Si in the following process. [31] Copyright 2016, John Wiley & Sons, Inc. cycling stability (454 mA h g −1 after 200 cycles) were obtained (Figure 10b,c). As a result, an initial charge capacity of 438 mA h g −1 and superior Adv.…”

“…Compared with extremely low-yield Scotch tape technique, liquid phase exfoliation via sonication or shear mixing has been proved fruitful to delaminate BP crystals. [31] Due to the strong interlayer interaction of BP, the best solvents tend to be those with high boiling points. [171] Dimethylformamide and dimethyl sulfoxide are also demonstrated as appropriate solvents for fabricating atomically thin BP nanoflakes and kept as uniform and stable dispersions after the sonication.…”

“…[182] To reduce the deterioration of BP nanosheets, it is widely adopted to treat them under vacuum or inert environment or by shortening the exposure time to the air. [31] For comparison, phosphorene-graphene hybrid (denoted by PG sample) was also prepared via conventional annealing process done under H 2 /Ar atmosphere. Atomic layer deposited AlO x on BP nanosheets has been demonstrated to effectively suppress its ambient degradation (Figure 9a,b).…”

“…A key obstacle that prevents the commercialization of these alloy-based anodes is that they undergo severe capacity fading upon cycling, [4,15] which can be ascribed to a couple of reasons. [17,[31][32][33][34][35] To date, enormous research attention has been devoted to Sodium-ion batteries (SIBs) are considered as promising alternatives to lithium-ion batteries owing to the abundant sodium resources. Meanwhile, anodes for SIBs suffer from larger volume expansion than LIB electrodes owing to the larger radius of Na + , and this presents a bigger challenge for SIB anodes in suppressing stress generated within the active anode materials and buffering the capacity decay of cells during (de)sodiation process.…”

“…One commonly recognized reason is the aggregation (slower kinetics due to loss of nanoscale diffusion distance) and pulverization (loss of electrical contact) of active materials induced by severe volume variation. [17,[31][32][33][34][35] To date, enormous research attention has been devoted to Sodium-ion batteries (SIBs) are considered as promising alternatives to lithium-ion batteries owing to the abundant sodium resources. [4,[19][20][21][22][23][24][25] Additionally, solid electrolyte interphase (SEI) layers form continuously accompanied with the newly exposed surfaces of active materials during cycling.…”