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

Aqueous Zn-ion batteries are promising for grid-scale storage, yet cathode capacities are often limited by the sluggish kinetics and poor reversibility of deep Zn²⁺ insertion. Although extensive efforts have focused on tuning cathode chemistries, the cathode-current collector contact remains largely overlooked as a kinetic bottleneck where ionic and electronic transport become mismatched. Here, we introduce a ferroelectric-conductive BaTiO₃@carbon nanotube (BTO@CNT) bridging interlayer between VO₂ cathodes and Ti collectors, constructed via catalytic pyrolysis to integrate BTO nanoparticles within a percolating CNT network. The CNT framework preserves durable ohmic contact and efficient electronic conduction during cycling, while ferroelectric polarization from BTO alleviates the large voltage hysteresis associated with deep Zn²⁺ insertion in VO₂ cathodes. Together, these effects improve the synchronization between Zn²⁺ insertion and electron delivery at the electrode level, suppress kinetic trapping, and enable deeper and more reversible charge storage. As a result, BTO@CNT-modified 3.28 Ah Zn||VO₂ pouch cells cycle stably for over 130 cycles, whereas control cells show pronounced capacity fading from the fifth cycle. More broadly, this ferroelectric-conductive bridging strategy establishes functional interlayers as a practical route to regulate active-material-current-collector interfaces in aqueous batteries.