Interface Modulation of Metal Sulfide Anodes for Long‐Cycle‐Life Sodium‐Ion Batteries

Abstract

Although studies of transition metal sulfides (TMS) as anode materials for sodium‐ion batteries are extensively reported, the short cycle life is still a thorny problem that impedes their practical application. In this work, a new capacity fading mechanism of the TMS electrodes is demonstrated; that is, the parasitic reaction between electrolyte anions (i.e., ClO4−) and metal sulfides yields non‐conductive and unstable solid‐electrolyte interphase (SEI) and meanwhile, corrosively turns metal sulfides into less‐active oxides. This knowledge guides the development of an electrochemical strategy to manipulate the anion decomposition and construct a stable interface that prevents extensive parasitic reactions. It is shown that introducing sodium nitrate to the electrolyte radically changes the Na+ solvation structure by populating nitrate ions in the first solvation sheath, generating a stable and conductive SEI layer containing both Na3N and NaF. The optimized interface enables an iron sulfide anode to stably cycle for over 2000 cycles with negligible capacity loss, and a similar enhancement in cycle performance is demonstrated on a number of other metal sulfides. This work discloses metal sulfides’ cycling failure mechanism from a unique perspective and highlights the critical importance of manipulating the interface chemistry in sodium‐ion batteries.

Interfacial‐Catalysis‐Enabled Layered and Inorganic‐Rich SEI on Hard Carbon Anodes in Ester Electrolytes for Sodium‐Ion Batteries

“…The SEI layers on the HC-CA anodes contain significantly large-area crystal regions in the inner layer and very thin amorphous regions in the outer layer, indicating an inorganic-dominated and layered structure, [8,33] which is similar to the SEI derived from ether electrolyte. [46] The enlarged crystalline parts (Figure 5b,d,f,h) show obvious lattice fringes with interplanar spacings of 0.257, 0.264/0.263 or 0.232, and 0.207/0.206 nm, corresponding to Na 2 CO 3 (310), [56] NaF(111) [57] or NaF(200), [58] and Na 2 O(220), [59] respectively, which match well with XPS measurements. Among the three HC-CA anodes, Na 2 O dominates the SEI on HC-CA-10%, and Na 2 O/Na 2 CO 3 is present in a high proportion in the SEI on the HC-CA-20% anode.…”

Breaking Barriers: Binder-Assisted NiS/NiS2 Heterostructure Anode with High Initial Coulombic Efficiency for Advanced Sodium-Ion Batteries

“…On the other hand, the development of alternative energy storage devices has come into focus. , Developing low-cost and environment-friendly energy storage devices is crucial for utilizing and exploiting clean energy sources. Among them, sodium-ion batteries (SIBs) are considered up-and-coming energy storage devices for the future due to the abundance of sodium resources in the earth’s crust and oceans as well as their low cost. − The chemical mechanism of SIBs is similar to LIBs, but the developments of suitable anode materials with the capability of accommodating large sodium ions are highly desirable. , Moreover, the large volume expansion during charging and discharging in SIBs, low ICE, and low energy density, alongside the formation of the solid-electrolyte (SEI) film on the electrode surface, severely undermine the electrode integrity. − Designing the electrode material is the key factor in controlling the volume expansion and enhancing the sodium-ion diffusion within the electrode. Furthermore, huge mass expansion and structural evolution during ion insertion/extraction hinder the practical application of SIBs.…”

“…Transition metal sulfides have gained much attention due to their high electronic conductivity, unique electronic structure, and rich redox chemistry. , These promising properties make them interesting for sodium-ion storage systems. Among them, nickel sulfide (NiS) and nickel disulfide (NiS 2 ) have drawn much attention for practical energy storage applications due to their low cost, high theoretical capacity, and environmental friendliness. − However, severe pulverization due to the large volume changes during the sodiation/desodiation process, poor electrical conductivity, and slow ion diffusion restrict their practical applications. , Different strategies have been adopted to address these issues, such as compositing with carbon and applying different polymer binders, additives, separators, and electrolytes to ameliorate electronic conductivity. , Among these components, a polymer binder is important in the battery to glue the active material to the current collector and maintain the mechanical integrity of the electrode. , For metal sulfide anodes, which undergo a huge volume change during the sodiation/desodiation process, polymer binders with a strong cohesive strength can play an important role in maintaining the structural integrity and accommodating the large volume change during cycling . Particularly, the mechanical stability of the electrode is the primary factor in achieving the superior electrochemical performance of the anode materials.…”

“…Transition metal sulfides have gained much attention due to their high electronic conductivity, unique electronic structure, and rich redox chemistry. 3,18 These promising properties make them interesting for sodium-ion storage systems. Among them, nickel sulfide (NiS) and nickel disulfide (NiS 2 ) have drawn much attention for practical energy storage applications due to their low cost, high theoretical capacity, and environmental friendliness.…”

“…19−21 However, severe pulverization due to the large volume changes during the sodiation/desodiation process, poor electrical conductivity, and slow ion diffusion restrict their practical applications. 3,22 Different strategies have been adopted to address these issues, such as compositing with carbon and applying different polymer binders, additives, separators, and electrolytes to ameliorate electronic conductivity. 12,23 Among these components, a polymer binder is important in the battery to glue the active material to the current collector and maintain the mechanical integrity of the electrode.…”