Deactivating Defects in Graphenes with Al₂O₃ Nanoclusters to Produce Long‐Life and High‐Rate Sodium‐Ion Batteries

Abstract

LIBs), delivers very limited reversible capacity in SIBs due to its inability to form stable low-stage graphite intercalation compounds (GICs). [4,5] Thus, most research has turned to nongraphitic carbons including nanocarbons and hard carbons, [6][7][8][9][10] whose capacities are significantly higher than graphite. It has been found that the structure could be well controlled to realize the high efficiency and reversibility. Our group has reported that the commercial carbon molecular sieves with abundant ultrasmall (0.3-0.5 nm) pores can achieve high efficiency and reversible capacity. [11] Intensive researches have also revealed that the nongraphitic carbons with low specific surface areas (SSA) exhibit a high electrochemical stability. [12][13][14][15][16] However, these carbons show limited rate capability and relatively low capacity. Thus, it is desired to improve the SSA to enhance the rate performance and capacity. Unfortunately, nongraphitic carbons with large SSA and a large number of defects typically exhibit an extremely low initial Coulombic efficiency (ICE) and unsatisfactory cyclic stability because of uncontrollable electrolyte decomposition and ineffective formation of a solid electrolyte interphase (SEI). In a previous report, we used reduced graphene oxide (rGO) as a model anode and found that an ether-based electrolyte can greatly suppress the Carbon materials are the most promising anodes for sodium-ion batteries (SIBs), but low initial Coulombic efficiency (ICE) and poor cyclic stability hinder their practical use. It is shown herein, that an effective but simple remedy for these problems can be achieved by deactivating defects in the carbon with Al 2 O 3 nanocluster coverage. A 3D porous graphene monolith (PGM) is used as the model material and Al 2 O 3 nanoclusters around 1 nm are grown on the defects of graphene. It is shown that these Al 2 O 3 nanoclusters suppress the decomposition of conductive sodium salt in the electrolyte, resulting in the formation of a thin and homogenous solid electrolyte interphase (SEI). In addition, Al 2 O 3 nanoclusters appear to reduce the detrimental etching of the SEI by hydrogen fluoride (HF) and improve its stability. Therefore, after the introduction of Al 2 O 3 nanoclusters, the ICE, cyclic stability, and rate capability of the PGM are greatly improved. A higher ICE (70.2%) and capacity retention (82.9% after 500 cycles at 0.5 A g −1 ) than those of normally reported for large surface area carbons are achieved. This work indicates a new way to deactivate defects and modify the SEI of carbon materials, and hopefully accelerate the commercialization of carbon materials as anode materials for SIBs.

Improved potassium ion storage performance of graphite by atomic layer deposition of aluminum oxide coatings

“…The value of I D /I G decreases with ALD coating cycles increase, which was because of the coverage of defective sites by the Al 2 O 3 coating. Defective sites can efficiently adsorb ions and then form strong bonds with the oxides …”

“…Defective sites can efficiently adsorb ions and then form strong bonds with the oxides. [30][31][32][33] The elements' chemical bonding states and surface contents of 20-ALD-NG and 50-ALD-NG were measured by XPS. Figure 2C is a part of the original XPS survey spectra.…”

Two‐dimensional materials of group‐IVA boosting the development of energy storage and conversion

“…But, the lack of suitable electrode materials strictly hinders the development of metal‐ion batteries. Graphene, a class of superior thermal and electrical conductors, can not only act as a conductive filler but also form the desirable nanocomposite electrode structures in conjunction with carbon nanotubes, transition metal oxides, and so forth to enhance ion infusion, electron transfer, and alleviate the volume expansion 80‐82,90,91‐96 . The strategy for the feasible nanostructured assembly of a three‐dimensional porous graphene/niobia (Nb 2 O 5 ) composite was applied by Sun et al 83 to prepare the 3D electrode architecture delivering high areal capacity and high‐rate capability at practical levels of mass loading.…”

“…Graphene, a class of superior thermal and electrical conductors, can not only act as a conductive filler but also form the desirable nanocomposite electrode structures in conjunction with carbon nanotubes, transition metal oxides, and so forth to enhance ion infusion, electron transfer, and alleviate the volume [79] expansion. [80][81][82]90,[91][92][93][94][95][96] The strategy for the feasible nanostructured assembly of a three-dimensional porous graphene/ niobia (Nb 2 O 5 ) composite was applied by Sun et al 83 to prepare the 3D electrode architecture delivering high areal capacity and high-rate capability at practical levels of mass loading. Subsequently, Zhao et al 84 found that densely packed Li x M/graphene foils (M = Si, Sn, or Al) would serve as air-stable and freestanding anodes guaranteeing stable structures and exceptional cyclabilities ( Figure 10).…”

Accurate Control Multiple Active Sites of Carbonaceous Anode for High Performance Sodium Storage: Insights into Capacitive Contribution Mechanism

“…Nonetheless, the larger radius of sodium (1.02 Å) compared with lithium (0.76 Å) causing serious volume expansion during the storage/release processes . In addition, the standard reduction potential of sodium (−2.71 V vs standard hydrogen electrode (SHE)) is also more positive than lithium (−3.04 V vs SHE), hence simultaneous causing low operating voltage and poor energy density . To further promote the advance progress of RT‐SIBs technologies, it is urgent to develop appropriate host materials for sodium storage …”