Robust Polyhedral CoTe₂–C Nanocomposites as High-Performance Li- and Na-Ion Battery Anodes

Abstract

Cobalt ditelluride nanocrystallites (average size ∼3–6 nm) embedded in robust carbon polyhedra (polyhedral CoTe2–C) were synthesized by a simple two-step sequential annealing process using a zeolitic imidazolate framework (ZIF-67), and their electrochemical behavior in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) was studied. The mechanism of structural phase changes in the polyhedral CoTe2–C was thoroughly investigated by various ex situ analysis tools. During Li- and Na-insertion/extraction, the CoTe2 nanocrystallites in the polyhedral C involved a conversion/recombination reaction. Because of the homogeneous embedding of CoTe2 nanocrystallites in a robust polyhedral carbon matrix and the electrochemical recombination reaction of CoTe2, agglomeration of CoTe2 nanocrystallites was prevented and volume strain during cycling was alleviated, which contributed to excellent electrochemical performance. The polyhedral CoTe2–C exhibited excellent electrochemical performance for Li- and Na-ion storage, including large reversible capacities (the initial reversible capacity: 500 mA h g–1 for LIBs and 323 mA h g–1 for SIBs), stable capacity retentions over 200 cycles, and fast C-rate behavior (386 mA h g–1 for LIBs at 3 C and 240 mA h g–1 for SIBs at 2 C rates, respectively) with excellent cyclic stability at a high 1 C rate (∼480 mA h g–1 for LIBs over 200 cycles and ∼250 mA h g–1 for SIBs over 200 cycles), which suggests that polyhedral CoTe2–C is highly suitable as a potential anode material for both LIBs and SIBs. This work provides a distinct architecture for a composite material that will be highly applicable for high-performance LIB and SIB anodes.

Recent advances of metal telluride anodes for high-performance lithium/sodium–ion batteries

“…47 Besides, non-layered CoTe 2 /FeTe 2 with inert Co/Fe also adopted the same ion storage mechanism, which has been confirmed by ex situ XRD, EXAFS, SAED, and corresponding HR-TEM analyses. 37,43 On the other hand, non-layered ZnTe with active Zn resulted in an alloying reaction between Zn and Li after the conversion reaction. 36 Furthermore, it is noteworthy that Na + intercalation occurred initially in the non-layered SnTe/C nanocomposite in addition to the processes during the conversion and alloying stages.…”

“…Interestingly, Ganesan et al 37 produced polyhedral Co–C based on the carbonization of zeolitic imidazolate framework (ZIF-67), which was then successfully transformed to CoTe 2 –C via a tellurization process, in which CoTe 2 nanocrystallites (3–6 nm) were embedded homogeneously in the polyhedral carbon matrix (Fig. 8A).…”

“…112 Wang et al 113 synthesized cobalt telluride nanoparticles with different components encapsulated in the nitrogen-doped mesoporous graphitic (CoTe 2 /C, Co 1.11 Te 2 /C and CoTe/C) based on the ZIF-67 by adjusting the tellurization temperatures (680 °C, 720 °C, 780 °C) under Ar atmosphere. Ganesan et al 37 first transformed the polyhedral ZIF-67 to Co–C polyhedral, followed by annealing at 600 °C under Ar gas flow, obtaining CoTe 2 –C nanocomposite, which consisted of ∼3–6 nm uniformly distributed CoTe 2 nanocrystallites embedded in a robust polyhedral carbon matrix. Furthermore, He et al 114 produced Fe-doped cobalt telluride nanoparticles coated by nitrogen-doped carbon nanotube frameworks (Fe–Co 1.11 Te 2 @NCNTF- x ) after annealing the Fe-etched ZIF-67 with Te powder at 700 °C for 2 h under 10% H 2 /Ar atmosphere.…”

“…30 Furthermore, it can deliver an outstanding volumetric capacity (2625 mA h cm −3 ) based on the high density of 6.25 g cm −3 and gravimetric capacity (420 mA h g −1 ). 31 The appreciable and unique characteristics of Te have inspired the investigation of the properties of different metal tellurides, including Bi 2 Te 3 , 32 Sb 2 Te 3 , 33 MoTe 2 , 34 GeTe, 35 ZnTe, 36 CoTe 2 37 and so forth for use in LIBs and SIBs as demonstrated by over 50 published articles on this subject.…”

Bismuth and its nanocomposite: Reaction mechanism and rational nanocomposite fabrication process for superior sodium‐ion battery anodes

“…A template of zeolitic imidazolate framework-67 (ZIF-67) was prepared using a well-known synthetic procedure. 41,42 Two precursors (10.0 mmol of cobalt (II) nitrate hexahydrate and 40.0 mmol of 2-methylimidazole) were dissolved in 100 mL methanol. The dissolved solution was mixed and stirred for 20 minutes.…”