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

Abstract

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-ZrO 2 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 Zn 2+ transfer number (0.69), and the ZrO 2 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 Zn 2+ 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||ZnSO 4 ||MnO 2 /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. A composite separator with excellent ionic conductivity, high Zn 2+ transfer number, low-cost and easily-fabricated features is prepared from cellulose nanofibers and ZrO 2 particles, and employed to improve the poor reversibility of Zn anode and hinder the formation of passivated byproduct as well as serious dendrite growth. ● Dendrites-free zinc anode is obtained using ZrO 2 -cellulose (ZC) separator. ● ZrO 2 particles can offer directional electric field and low nucleation overpotential via Maxwell-Wagner polarization. ● The rate capability and cyclability of Zn||ZnSO 4 ||MnO 2 /graphite batteries can be significantly boosted via the ZC separator. ● The preparation process of ZC separator is facile, cost effective and scalable.