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High‐Performance Sodium Metal Anodes Enabled by a Bifunctional Potassium Salt
Author(s) -
Shi Qiuwei,
Zhong Yiren,
Wu Min,
Wang Hongzhi,
Wang Hailiang
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201803049
Subject(s) - bifunctional , electrolyte , inorganic chemistry , anode , metal , lithium (medication) , electrode , potassium , chemistry , prussian blue , salt (chemistry) , materials science , chemical engineering , electrochemistry , organic chemistry , medicine , engineering , endocrinology , catalysis
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 −2 for hundreds of hours.