Fabrication of ZnSe/C Hollow Polyhedrons for Lithium Storage

Abstract

ZnSe has got extensive attention for high-performance LIBs anode due to its remarkable theoretical capacity and environmental friendliness. Nevertheless, the large volume variation for the ZnSe in the discharge/charge processes brings about rapid capacity fading and poor rate performance. Herein, ZnSe/C hollow polyhedrons are successfully synthesized by selenization of zeolitic imidazolate framework-8 (ZIF-8) with resorcinol-formaldehyde (RF) coating. The protection of C layer derived from RF coating layer and Ostwald ripening during the process of selenization play important roles in promoting formation of ZnSe/C hollow polyhedrons. The ZnSe/C hollow polyhedrons exhibit good rate performance and long-term cycle stability (345 mAh g À 1 up to 1000 cycles at 1 A g À 1 ) for lithium ion batteries (LIBs) anode. The improved electrochemical performance is benefit from the unique ZnSe/C hollow structure, in which the hollow structure can effectively avoid terrible volume expansion, and the thin ZnSe/C shell can not only provide adequate diffusion paths of lithium ions and but also enhance the electronic conductivity.

Research progress on ZnSe and ZnTe anodes for rechargeable batteries

“…Note: ZnTe may undergo a partial recombination reaction; i.e., eqn (1) and (3) are not completely reversible but leave a minor amount of Te in an elemental state after A extraction; in some references, elemental Se also presents in the charge/discharge process for ZnSe). 16,22,24,29,31,37,40,41,[43][44][45][46][47]…”

“…44 Notably, for the TMCs including ZCs, they usually exhibited a pseudocapacitance-dominated behavior (rather than diffusion-controlled process), especially at high rates, which are beneficial for highperformance batteries. 17,31,46,[48][49][50] Zinc chalcogenides typically have a cubic (sphalerite, or zinc blende) crystal structure, but can be also prepared as halite crystals or in hexagonal crystals (wurtzite structure). Those with unusual layered structures (e.g., tetragonal, t-ZnX, X = S, Se) prefer the AA stacking pattern (theoretical d ZnS = 2.40 Å, and d ZnSe = 2.48 Å in double-layer sheets) when forming multilayer structures, although exhibiting an interesting variation of interlayer distance (i.e., shortening to 2.33 Å for t-ZnS bulk but elongating to 2.91 Å for t-ZnSe bulk).…”

“…The elaborately designed structures of these ZnSe/ZnTe structures, especially low-dimensional or hollow/porous structures, provide adequate diffusion paths for ions and effectively accommodate volume variation (e.g., buffer the strain thereof ) in the repeated charging/discharging process. 46,69…”

“…through the selenization/pyrolysis of specific MOFs (ZIF-8 and its variants), have been increasingly reported in recent years and are demonstrating synergistic effects for enhanced performances along with the synchronously formed heteroatom doped carbon coating or matrix. 46,103 Metal-organic frameworks (MOFs) have recently been increasingly utilized as the precursors and/or templates to develop transition metal oxides or chalcogenides (TMOs or TMCs) with controllable morphologies and porosity, revealing great potential in energy storage and conversion applications. 84 Due to the reinforcement, modification or synergistic effect between two metal components between different components, special properties can be endowed upon the multi-metal oxides or chalcogenides.…”

“…, eqn (1) and (3) are not completely reversible but leave a minor amount of Te in an elemental state after A extraction; in some references, elemental Se also presents in the charge/discharge process for ZnSe). 16,22,24,29,31,37,40,41,43–47 x A + + ZnX + x e − ↔ A x X + Zn (0 < x ≤ 2) x A + + Zn ↔ A x Zn − x e − (0 < x ≤ 1)( x + 2)A + + ZnX + ( x + 2)e − ↔ A 2 X + A x Zn (0 < x ≤ 1)…”