Two‐in‐one shell configuration for bimetal selenides toward fast sodium storage within broadened voltage windows

Abstract

The shell structure design has been recognized as a highly efficient strategy to buffer the severe volume expansion and consecutive pulverization of conversion-type anodes. Nevertheless, construction of a functional shell with a stabilized structure that meets the demands of both high electronic conductivity and feasible pathways for Na + ions has been a challenge so far.Herein, we design a two-in-one shell configuration for bimetal selenides to achieve fast sodium storage within broadened voltage windows. The hybridized shell, which benefits from the combination of titanium dioxide quantum dots and amorphous carbon, can not only effectively buffer the strain and maintain structural integrity but also allow facile and reversible transport of electrons and Na + uptake for electrode materials during sodiation/ desodiation processes, resulting in increased reaction kinetics and diffusion of sodium ions, conferring many benefits to the functionality of conversiontype electrode materials. As a representative material, Ni-CoSe 2 with such structural engineering shows a reversible capacity of 515 mAh g −1 at 0.1 A g −1 and a stable capacity of 416 mAh g −1 even at 6.4 A g −1 ; more than 80% of the capacity at 0.1 A g −1 could be preserved, so that this strategy holds great promise for designing fast-charging conversion-type anodes in the future.

Nitrogen-doped carbon decorated 3D NiCoSe2 micro-flowers as high-performance anode materials for lithium-ion batteries

“…0.1579 g Ni-Co-MOF and 0.4737 g selenium powder were weighed, ground and mixed evenly in an agate bowl, poured into a sinter, and then put into a tube furnace filled with argon (Ar), heated to 700, 800 and 900 1C, respectively, at a heating rate of 2 1C min À1 , and calcined for 120 min. After cooling to room temperature and grinding evenly, the microflower NiCoSe 2 /NC composites can be obtained, 19,30 which were named NiCoSe 2 /NC-700, NiCoSe 2 /NC-800 and NiCoSe 2 /NC-900, respectively.…”

Developing High‐Performance Metal Selenides for Sodium‐Ion Batteries

“…However, these materials suffer from severe volume expansion/shrinking during the (de)sodiation process, resulting in structural collapse and rapid capacity degradation. [49][50][51] The generic electrochemical reaction equations are shown below:…”

“…However, these materials suffer from severe volume expansion/shrinking during the (de)sodiation process, resulting in structural collapse and rapid capacity degradation. [ 49–51 ] The generic electrochemical reaction equations are shown below: $$\[{\rm{MS}}{{\rm{e}}_x} + y{\rm{N}}{{\rm{a}}^ + } + {\rm{y}}{e^ - } \leftrightarrow {\rm{N}}{{\rm{a}}_y}{\rm{MS}}{{\rm{e}}_x}\]$$ $$\[{\rm{N}}{{\rm{a}}_y}{\rm{MS}}{{\rm{e}}_x} + \left( {2x - y} \right){\rm{N}}{{\rm{a}}^ + } + \left( {2x - y} \right){{\rm{e}}^ - } \leftrightarrow x{\rm{N}}{{\rm{a}}_2}{\rm{Se}} + {\rm{M}}\]$$ $$\[{\rm{M}} + n{\rm{N}}{{\rm{a}}^ + } + n{{\rm{e}}^ - } \leftrightarrow {\rm{N}}{{\rm{a}}_n}{\rm{M}}\]$$where M is Sn, Sb, and Bi. As shown in Figure 2d, the SnSe 2 exhibits a typical sodium‐storage mechanism of intercalation‐conversion‐alloying reactions.…”

Insights into the Dynamic Evolution of Defects in Electrocatalysts

“…Catalyst is widely applied in the fields of energy storage, chemistry, and electrocatalysis. [18][19][20][21][22][23][24][25][26][27] The activity of a catalyst is closely related to its structural characteristics and electronic configuration. Especially for the electrocatalytic oxidation reaction, the high-state transition metal cations are the typical highly active sites in water electrolysis.…”