Explicating the Sodium Storage Kinetics and Redox Mechanism of Highly Pseudocapacitive Binary Transition Metal Sulfide via Operando Techniques and Ab Initio Evaluation

Abstract

The economic advantage of sodium resources has triggered worldwide enthusiasm in sodium‐ion batteries (SIBs). As a new breed of transition metal sulfides, binary metal sulfides (BMS) have garnered increasing interests due to its pseudocapacitive capabilities but with limited reports to address its potentials. To address them, bimetallic nickel cobalt sulfide (NiCo2S4, or NCS) embedded in graphene aerogel matrix (NCSGO) with excellent reaction kinetics and rate performance are studied by first‐principles methods and operando techniques to elucidate its sodiation kinetics and redox mechanism. The kinetic analysis on sodiation behavior reveals a major contribution of pseudocapacitance versus total capacity, providing fast reaction kinetics and highly reversible cycling. The sodiation dynamics are unraveled by first‐principles approach manifesting favorable Na+ adsorption kinetics (<−2.1 eV) and extremely low diffusion barrier (0.28 eV), indicating the strong adsorption and diffusion capability for SIBs. The redox mechanism is studied and confirmed via operando techniques that NCS‐based electrodes are based on both a combination of intercalation and conversion reactions. Following the results of the joint experimental‐computational approach, the excellent BMS SIBs performance enabled by conversion‐based and fast pseudocapacitive sodiation kinetics provides a promising strategy for developing SIBs anodes with both high specific capacity and fast rate response.

Rechargeable Aqueous Zinc-Ion Batteries in MgSO4/ZnSO4 Hybrid Electrolytes

“…In order to establish the detailed structure transformation and electrochemical behavior during the electrochemical reaction, in situ XRD was conducted during the first discharge–charge process to reveal the evolution of the peak intensities [ 33 , 34 ]. Figure 5 a illustrates the first discharge–charge profile for the MgVO electrode in hybrid 1.0Zn1.0Mg electrolyte with the selected operando XRD scan voltages, while a 2D mapping contour plot with XRD patterns in the selected angle region is displayed in Fig.…”

Recent Tactics and Advances in the Application of Metal Sulfides as High‐Performance Anode Materials for Rechargeable Sodium‐Ion Batteries

“…As shown in the previous section, pseudocapacitance is a surface-based phenomenon that can be promoted by surface and nanostructuring engineering approaches. [95,[346][347][348] In fact, a large number of research works have demonstrated the possibility of converting bulk diffusion-based materials to surfacebased pseudocapacitive charge storage materials by nanoscale and surface engineering. [346,349] Specifically for SIBs anode materials, the promotion of surface-based reaction can con-siderably enhance their rate performance due to the fast ion transport.…”

“…[353][354][355][356] However, its operation at various sodiation potentials induces intercalation and conversion reactions (the latter increases the capacity contribution). [348,357,358] One of the examples of exploiting the highly pseudocapacitive spinel type NCS was demonstrated by Yang et al [348] An aerogel composite containing LDH and graphene was synthesized as the precursor followed by a facile sulfurization process to obtain an NCS hybrid composite structure (NCSGO). Its large pseudocapacitive contribution (≈85%) was mainly attributed to the intrinsic material properties rather than to the utilized surface engineering approach.…”

One-dimensional core–shell motif nanowires with chemically-bonded transition metal sulfide-carbon heterostructures for efficient sodium-ion storage

“…11 Generally, common TMS materials are characterized by limited electrical conductivity and poor chemical/mechanical stability in their bulk form, which not only impacts their electrochemical reaction performance, but can also result in severe volume changes during the charge/discharge cycles, eventually compromising the electrode structure and causing the shedding of the active material. 13,14 Although optimized single TMS nanostructures could improve the electrochemical performance of the electrode to some extent, 15,16 this strategy cannot address all aspects of the challenges discussed above. In this regard, innovative strategies for achieving 1D core-shell heterostructures, especially 1D TMS@carbon heterostructured nanowires, are highly desired in the industry of energy storage applications.…”