Stable interphase chemistry of textured Zn anode for rechargeable aqueous batteries

织构调控助力实现界面稳定的可充电水系锌电池负极

Despite the advances of aqueous zinc(Zn)batteries as sustainable energy storage systems,their practical application remains challenging due to the issues of spontaneous corrosion and dendritic deposits at the Zn metal anode.In this work,conformal growth of zinc hydroxide sulfate(ZHS)with dominating(001)facet was realized on(002)plane-dominated Zn metal foil fabricated through a facile thermal annealing process.The ZHS possessed high Zn^(2+)conductivity(16.9 mS cm^(-1))and low electronic conductivity(1.28×10^(4)Ωcm),and acted as a heterogeneous and robust solid electrolyte interface(SEI)layer on metallic Zn electrode,which regulated the electrochemical Zn plating behavior and suppressed side reactions simultaneously.Moreover,low self-diffusion barrier along the(002)plane promoted the 2D diffusion and horizontal electrochemical plating of metallic Zn for(002)-textured Zn electrode.Consequently,the as-achieved Zn electrode exhibited remarkable cycling stability over 7000 cycles at 2 mA cm^(-2)and 0.5 mAh cm^(-2)with a low overpotential of 25 mV in symmetric cells.Pairing with a MnO_(2)cathode,the as-achieved Zn electrode achieved stable cell cycling with 92.7%capacity retention after 1000 cycles at 10 C with a remarkable average Coulombic efficiency of 99.9%.

水系锌电池在储能领域具有广阔的应用前景.然而,其实际应用受到锌金属负极自发腐蚀副反应和不均匀沉积行为等问题的掣肘.本文通过简单的热退火工艺,制备了(002)晶面择优的锌金属负极.一方面,由于良好的晶格匹配性,锌金属电极表面可以共形生长具有优异Zn^(2+)离子电导率(16.9 mS cm^(-1))和较低电子电导率(1.28×10^(4)Ωcm)的(001)晶面主导的碱式硫酸锌固体电解质界面层,可有效抑制金属锌的自发腐蚀等副反应,并调节金属锌的电化学沉积行为.另一方面,锌金属(002)晶面具有较低的自扩散势垒,有利于锌离子在电极表面的二维扩散,促进金属锌的平面电化学沉积.以该(002)晶面择优的锌金属电极组装的对称电池实现了在2 mA cm^(-2)和0.5 mAh cm^(-2)条件下稳定循环7000次,且过电位仅为25 mV;其与MnO_(2)正极组装全电池后可实现在10C下循环1000次,且容量保持率高达92.7%,平均库伦效率为99.9%.