Modulating Zn deposition via ceramic-cellulose separator with interfacial polarization effect for durable zinc anode

The optimization strategies of electrode and electrolyte currently advocated for zinc dendrite suppression remain challenging for aqueous zinc-ion batteries (ZIBs) due to their complex manufacturing processes and non-economic prices. Here, a cellulose nanofibers-ZrO2 composite (ZC) separator with easily-fabricated and cost-effective features is developed to stabilize the zinc anode. The ZC separator is designed to enable excellent ionic conductivity (4.59 mS cm−1) and high Zn2+ transfer number (0.69), and the ZrO2 particles with high dielectric constant (ε = 25) offer a directional electric field via the Maxwell-Wagner polarization effect, which regulates uniform zinc deposition, accelerate the Zn2+ ions diffusion kinetics and repel anions, thus stabilizing zinc anode and suppressing passivation reactions. As a result, ZC separator renders zinc anode with dendrite‐free plating/stripping behavior, high Coulombic efficiency (99.5%) and exceptional cyclability (2000 h under 0.5 mA cm−2). Additionally, this developed composite separator can be extended to other insulating ceramics, or even random combinations. Moreover, the rate capability and cyclability of the as-assembled Zn||ZnSO4||MnO2/graphite coin and pouch cells also can be significantly boosted via the ZC separator, accompanied by the remarkable flexibility and integration ability. The ceramics-cellulose separators offer an appealing strategy for constructing advanced zinc anode for large-scale energy storage.