Operando monitoring of ion activities in aqueous batteries with plasmonic fiber-optic sensors

Abstract

Understanding ion transport kinetics and electrolyte-electrode interactions at electrode surfaces of batteries in operation is essential to determine their performance and state of health. However, it remains a challenging task to capture in real time the details of surface-localized and rapid ion transport at the microscale. To address this, a promising approach based on an optical fiber plasmonic sensor capable of being inserted near the electrode surface of a working battery to monitor its electrochemical kinetics without disturbing its operation is demonstrated using aqueous Zn-ion batteries as an example. The miniature and chemically inert sensor detects perturbations of surface plasmon waves propagating on its surface to rapidly screen localized electrochemical events on a sub-μm-scale thickness adjacent to the electrode interface. A stable and reproducible correlation between the real-time ion insertions over charge-discharge cycles and the optical plasmon response has been observed and quantified. This new operando measurement tool will provide crucial additional capabilities to battery monitoring methods and help guide the design of better batteries with improved electro-chemistries.

Methods for Rational Design of Advanced Zn‐Based Batteries

“…Here, we recommend a promising approach based on an optical fiber plasmonic sensor, which could insert on the surface of electrode and be sensitive to the concentration variations with nanoscale spatial resolution, for tracking the ion kinetics of AZBs without disturbing. [ 167 ] Using this method, we discovered that the PEDOT coating on MnO 2 could effectively improve the diffusion kinetics of H + but not Zn 2+ . We believe that it could further reveal the crucial factors to battery decay and provide guidance for stable electrode design.…”

Recent Advances of Carbon Materials in Anodes for Aqueous Zinc Ion Batteries

“…The first three metal ion batteries are still in the preliminary stage considering the slow reaction kinetics in the cathode and poor reversibility at the anode [14–19] . As a promising alternative, Zn‐based batteries enjoy several advantages: first, violent reaction with water is inhibited due to the suitable potential of Zn/Zn 2+ (−0.76 V vs. standard hydrogen electrode (SHE)); second, volume‐limited applications are favored because of the high volumetric capacity (5849 mAh ⋅ cm −3 ) based on the two‐electron redox reaction; third, unlike other metals with multiple‐electron transfer properties, the size of hydrated Zn ions is smaller, facilitating the reversible insertion/extraction process through the layered cathode structures; fourth, passivation of the Zn surface is not serious as other counterparts, lowering the battery internal resistance; fifth, the cost of Zn is low; sixth, aqueous electrolytes are featured with environmental friendliness and high ionic conductivity [20–27] …”

“…[14][15][16][17][18][19] As a promising alternative, Zn-based batteries enjoy several advantages: first, violent reaction with water is inhibited due to the suitable potential of Zn/Zn 2 + (À 0.76 V vs. standard hydrogen electrode (SHE)); second, volumelimited applications are favored because of the high volumetric capacity (5849 mAh • cm À 3 ) based on the two-electron redox reaction; third, unlike other metals with multiple-electron transfer properties, the size of hydrated Zn ions is smaller, facilitating the reversible insertion/extraction process through the layered cathode structures; fourth, passivation of the Zn surface is not serious as other counterparts, lowering the battery internal resistance; fifth, the cost of Zn is low; sixth, aqueous electrolytes are featured with environmental friendliness and high ionic conductivity. [20][21][22][23][24][25][26][27] Despite the merits mentioned above, most of the Zn-based batteries are primary type with a poor reversibility. Only in the last ten years, the incorporation of α-MnO 2 cathodes considerably improves the reversible intercalation of Zn ions, symbolizing a breakthrough of Zn-ion batteries (ZIBs) (Figure 1a).…”

Design and fabrication of novel optical fiber architectures for sensing applications

“…Sensors for measuring the SRI [182][183][184][185][186][187], as well as biosensors [188][189][190][191] (mostly based on the combination of TFBGs with SPRs) have also been manufactured employing TFBGs. Finally, TFBG-based sensors have recently acquired great relevance for monitoring the electrochemical and thermal activity in batteries [192,193].…”

“…In [192] TFBGs are used to simultaneously monitor the temperature and refractive index inside the batteries, parameters that are linked to the chemical evolution of the electrolyte, and to measure the turbidity of the electrodes. On the other hand, a gold-coated TFBG is employed in [193] to monitor the electrochemical kinetics of aqueous zinc-ion batteries.…”