Cao Longsheng, Li Dan, Deng Tao, Li Qin, Wang Chunsheng
Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, 20742, USA.
Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20742, USA.
Angew Chem Int Ed Engl. 2020 Oct 19;59(43):19292-19296. doi: 10.1002/anie.202008634. Epub 2020 Aug 20.
Aqueous Zn batteries are promising energy-storage devices. However, their lifespan is limited by irreversible Zn anodes owing to water decomposition and Zn dendrite growth. Here, we separate aqueous electrolyte from Zn anode by coating a thin MOF layer on anode and filling the pores of MOF with hydrophobic Zn(TFSI) -tris(2,2,2-trifluoroethyl)phosphate (TFEP) organic electrolyte that is immiscible with aqueous Zn(TFSI) -H O bulk electrolyte. The MOF encapsulated Zn(TFSI) -TFEP forms a ZnF -Zn (PO ) solid electrolyte interphase (SEI) preventing Zn dendrite and water decomposition. The Zn(TFSI) -TFEP@MOF electrolyte protected Zn anode enables a Zn||Ti cell to achieve a high average Coulombic efficiency of 99.1 % for 350 cycles. The highly reversible Zn anode brings a high energy density of 210 Wh kg (of cathode and anode mass) and a low capacity decay rate of 0.0047 % per cycle over 600 cycles in a Zn||MnO full cell with a low capacity ratio of Zn:MnO at 2:1.
水系锌电池是很有前景的储能装置。然而，由于水分解和锌枝晶生长，其寿命受到不可逆锌阳极的限制。在此，我们通过在阳极上涂覆一层薄的金属有机框架（MOF）层，并在MOF的孔中填充与水系Zn(TFSI)₂-H₂O本体电解质不混溶的疏水性Zn(TFSI)₂-三（2,2,2-三氟乙基）磷酸酯（TFEP）有机电解质，将水系电解质与锌阳极分离。MOF封装的Zn(TFSI)₂-TFEP形成了ZnF₂-Zn₃(PO₄)₂固体电解质界面（SEI），防止了锌枝晶和水分解。Zn(TFSI)₂-TFEP@MOF电解质保护的锌阳极使Zn||Ti电池在350次循环中实现了99.1%的高平均库仑效率。在锌与二氧化锰容量比为2:1的Zn||MnO₂全电池中，高度可逆的锌阳极在600次循环中带来了210 Wh kg⁻¹（基于阴极和阳极质量）的高能量密度以及每循环0.0047%的低容量衰减率。
