Reacquainting the Electrochemical Conversion Mechanism of FeS₂ Sodium-Ion Batteries by Operando Magnetometry

Abstract

In spite of the excellent electrochemical performance in lithiumion batteries (LIBs), transition-metal compounds usually show inferior capacity and cyclability in sodium-ion batteries (SIBs), implying different reaction schemes between these two types of systems. Herein, coupling operando magnetometry with electrochemical measurement, we peformed a comprehensive investigation on the intrinsic relationship between the ion-embedding mechanisms and the electrochemical properties of the typical FeS 2 /Na (Li) cells. Operando magnetometry together with ex-situ transmission electron microscopy (TEM) measurement reveal that only part of FeS 2 is involved in the conversion reaction process, while the unreactive parts form "inactive cores" that lead to the low capacity. Through quantification with Langevin fitting, we further show that the size of the iron grains produced by the conversion reaction are much smaller in SIBs than that in LIBs, which may lead to more serious pulverization, thereby resulting in worse cycle performance. The underlying reason for the above two above phenomena in SIBs is the sluggish kinetics caused by the larger Na-ion radius. Our work paves a new way for the investigation of novel SIB materials with high capacity and long durability.

Recent Progress on In Situ/Operando Characterization of Rechargeable Alkali Ion Batteries

“…For instance, the conversion mechanisms of FeS 2 in Li/Na-ion batteries were comprehensively investigated by Li et al via operando magnetometry. [37] It is demonstrated that the FeS 2 does not reduce to metallic Fe in SIBs completely, resulting in inactive cores with a lower specific capacity. Furthermore, the diameter for reduced Fe particles in SIBs is clarified to be smaller than that in LIBs, which hints that a worse electrode pulverization happening in SIBs.…”

Temperature prediction of lithium‐ion batteries based on electrochemical impedance spectrum: A review

“…The simulation methods of LIBs are mainly divided into thermal simulation and electrochemical simulation. Thermal simulation is mainly used to simulate the model of LIBs temperature distribution, thermal behavior, and safety based on the experiments of battery materials and thermal properties 64–68 . Thermal simulation can be used to calculate the temperature variation and its distribution under different conditions (ambient temperature, battery short‐circuit, battery external damage, etc.).…”

One-Pot Synthesized Amorphous Cobalt Sulfide With Enhanced Electrochemical Performance as Anodes for Lithium-Ion Batteries

“…Lithium-ion batteries (LIBs) have been wildly used in small consumer electronics, electric vehicles, and medical apparatus as energy storage devices due to their advantages of high energy density, long cycle life, high working voltage, no memory effect, small self-discharge, and wide operating temperature range ( Sun et al, 2010 ; Wang et al, 2020c ; Gu et al, 2021 ; Li et al, 2021a ; Li et al, 2021b ; Li et al, 2021c ; Li et al, 2021d ; Zhao et al, 2021 ; Liang et al, 2022 ). However, to apply in large-scale energy storage projects and other high-power systems, the electrochemical properties of power density, rate capacity, cycle stability, and safety issue should be further improved ( Sun et al, 2011 ; Zhang et al, 2019b ; Wang et al, 2020b ; Zhang et al, 2020a ; Wang et al, 2021b ).…”