Ferroelectric-Conductive Cathode-Collector Contacts Enable Deep and Reversible Zn Storage

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc-ion batteries (AZIBs) show promise for grid-scale energy storage.
• Cathode capacity in AZIBs is often limited by slow kinetics and poor reversibility of deep zinc ion (Zn²⁺) insertion.
• The interface between the cathode and current collector is a critical, yet overlooked, bottleneck for ion and electron transport.

Purpose of the Study:

• To address the kinetic limitations in AZIB cathodes by optimizing the cathode-current collector interface.
• To improve the efficiency and stability of deep Zn²⁺ insertion in AZIBs.
• To introduce a novel bridging interlayer strategy for enhancing electrode performance.

Main Methods:

• Fabrication of a ferroelectric-conductive BaTiO₃@carbon nanotube (BTO@CNT) interlayer via catalytic pyrolysis.
• Integration of the BTO@CNT interlayer between VO₂ cathodes and Ti current collectors.
• Electrochemical testing of modified and control Zn||VO₂ pouch cells.

Main Results:

• The BTO@CNT interlayer established a durable ohmic contact and efficient electronic conduction via the CNT network.
• Ferroelectric polarization of BTO effectively reduced voltage hysteresis during deep Zn²⁺ insertion.
• The interlayer improved synchronization of Zn²⁺ insertion and electron delivery, suppressing kinetic trapping and enabling deeper, reversible charge storage.
• Modified cells demonstrated stable cycling for over 130 cycles, significantly outperforming control cells.

Conclusions:

• The ferroelectric-conductive bridging interlayer strategy effectively regulates the active-material-current-collector interface in AZIBs.
• This approach enhances Zn²⁺ storage kinetics and reversibility, leading to improved battery performance.
• The developed interlayer presents a practical solution for advancing AZIB technology for grid-scale applications.