Shi Qiuwei, Zhong Yiren, Wu Min, Wang Hongzhi, Wang Hailiang
Department of Chemistry and Energy Sciences Institute, Yale University, 810 West Campus Drive, West Haven, CT, 06516, USA.
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai, 201620, China.
Angew Chem Int Ed Engl. 2018 Jul 16;57(29):9069-9072. doi: 10.1002/anie.201803049. Epub 2018 May 7.
Developing Na metal anodes that can be deeply cycled with high efficiency for a long time is a prerequisite for rechargeable Na metal batteries to be practically useful despite their notable advantages in theoretical energy density and potential low cost. Their high chemical reactivity with the electrolyte and tendency for dendrite formation are two major issues limiting the reversibility of Na metal electrodes. In this work, we introduce for the first time potassium bis(trifluoromethylsulfonyl)imide (KTFSI) as a bifunctional electrolyte additive to stabilize Na metal electrodes, in which the TFSI anions decompose into lithium nitride and oxynitrides to render a desirable solid electrolyte interphase layer while the K cations preferentially adsorb onto Na protrusions and provide electrostatic shielding to suppress dendritic deposition. Through the cooperation of the cations and anions, we have realized Na metal electrodes that can be deeply cycled at a capacity of 10 mAh cm for hundreds of hours.
开发能够长时间高效深度循环的钠金属负极，是可充电钠金属电池实际应用的先决条件，尽管它们在理论能量密度和潜在低成本方面具有显著优势。它们与电解质的高化学反应性和枝晶形成倾向是限制钠金属电极可逆性的两个主要问题。在这项工作中，我们首次引入双（三氟甲基磺酰）亚胺钾（KTFSI）作为双功能电解质添加剂来稳定钠金属电极，其中TFSI阴离子分解为氮化锂和氮氧化物，以形成理想的固体电解质界面层，而K阳离子优先吸附在钠凸起上并提供静电屏蔽以抑制枝晶沉积。通过阳离子和阴离子的协同作用，我们实现了钠金属电极能够以10 mAh cm的容量深度循环数百小时。
