Two-Dimensional Mesoporous Cobalt Sulfide Nanosheets as a Superior Anode for a Li-Ion Battery and a Bifunctional Electrocatalyst for the Li–O₂ System

Abstract

We report the synthesis of two dimensional (2D) Co 3 S 4 in nano thickness sheet-like morphology via simple hydrothermal process and its application towards electrochemical energy storage devices. Presence of unique mesopores with combination of core/shell nanoparticles in the nanosheets showed superior electrochemical performances as negative electrode for Li-ion (LIB) and electro-catalyst in Li-O 2 battery applications. High discharge capacity of ~968 mAh g -1 is noted after 60 cycles with excellent cycling stability when evaluated as anode for LIB. On the other hand, first discharge capacity of ~5917 mAh g -1 is observed with high reversibility of 95.72% for Li-O 2 battery point of view. This exceptional electrochemical performance in both applications is mainly attributed to the presence of mesoporous with core/shell 2D nanostructure, which translates more catalytic bi-functional (oxygen reduction reaction/oxygen evolution reaction) active sites for Li-O 2 and sustains the volume variations occurred in 3D way upon charge/discharge process for LIB applications. Ex-situ studies, like TEM, XPS and impedance spectroscopy are also carried out to validate the reaction mechanisms.

Porous carbon-wrapped mesoporous Co9S8 fibers as stable anode for Li-Ion Batteries

“…The obtained composites possess an unique structure including better crystallinity and mesoporous microstructure Co 9 S 8 nanocrystals with small diameter (15 nm) and the thin porous carbon overcoat, which can not only prevent aggregation and 17 volume change of the Co 9 S 8 nanoparticles, but also enables good conductivity and thus enhances electrochemical performance. The as-obtained Co 9 S 8 @C composites exhibit remarkable lithium storage performance including high specific capacity (~1565 mA h g -1 at a current density of 0.1 C), excellent cycling stability (~97% retention after 100 cycles) and high rate capability (~606 mA h g -1 for 300 cycles at 1 C).…”

“…[9][10][11] To obtain the enhanced specific capacity and good cyclic stability of electrode materials, one effective method is to construct appropriate nanostructures, [12][13][14] because nanostructured materials can resist the stress and accommodate the large volume variation during Li + insertion/desertion, leading to excellent cycling properties. [15,16] Thus, many attempts have been made in the past, such as, twodimensional mesoporous cobalt sulfides nanosheets, [17] three-dimensional rose-like Co 9 S 8 hierarchical architectures, [18] and yolk-shell microspheres of CoS 2 , [19] have shown improved electrochemical performances. Another attractive approach to 4 achieve anode materials with enhanced specific capacity and good cyclic stability is the design of cobalt sulfides/carbon hybrid materials, which is effective to prevent the aggregation and volume change during the electrochemical reactions.…”

Monodisperse cobalt sulfides embedded within nitrogen-doped carbon nanoflakes: an efficient and stable electrocatalyst for the oxygen reduction reaction

“…4 Therefore, great efforts have been devoted to searching for cost-effective non-precious metal or even metalfree catalysts for ORR in these energy conversion devices. Transition metal sulfides (TMSs) usually exhibiting higher conductivity compared with their oxide counterparts have recently attracted great attention for applications in electrocatalysts, [5][6][7] supercapacitors, 8,9 lithium-ion batteries, 10,11 and solar cells. 12,13 Cobalt sulfides have shown promise amongst all TMSs displaying the highest catalytic activity for ORR.…”

3D Interconnected Porous Graphene Sheets Loaded with Cobalt Oxide Nanoparticles for Lithium‐Ion Battery Anodes

“…So far, numerous binary and ternary metal oxides have been exploited as high‐performance anode materials for LIB applications . Among them, Co 3 O 4 is found to be attractive in terms of its high theoretical capacity (≈890 mAh g −1 ) and high power capability . One of the major issues for TMOs is capacity fading, because of the large volume expansion/contraction of the active material during conversion reaction .…”