Molten-LiCl induced thermochemical prelithiation of SiOx:Regulating the active Si/O ratio for high initial Coulombic efficiency  

作　　者：Yang Li Yong Qian Jie Zhou Ning Lin Yitai Qian 

机构地区：[1]Department of Applied Chemistry,University of Science and Technology of China,Hefei 230026,China [2]Hefei National Laboratory for Physical Sciences at the Microscale,University of Science and Technology of China,Hefei 230026,China

出　　处：《Nano Research》2022年第1期230-237,共8页纳米研究（英文版）

基　　金：support by the National Natural Science Foundation of China(Nos.21701163,21831006,21975244,21521001,and 22075268);the Natural Science Foundation of Anhui Provincial(No.1808085QB25)。

摘　　要：The low initial Coulombic efficiency(ICE)of SiOx anode caused by the irreversible generation of LiySiOz and Li20 during lithiation process limits its application for high energy-density lithium-ion batteries.Herein,we report a molten-salt-induced thermochemical.prelithiation strategy for regulating the electrochemically active Si/O ratio of SiOx and thus enhancing ICE through thermal treatment of pre-synthesized LiNH2-coated SiOx in molten LiCl at 700℃.Bulk SiOx micro-particle was transformed into pomegranatelike prelithiated micro-cluster composite(M-Li-SiOx)with SiOx core and outer nano-sized agglomerates consisting of Li2Si20s,SiO2,and Si.Through the analysis of the reaction intermediates,molten-UC!could initiate reactions and promote mass transfer by the continuous extraction of oxygen component from SiOx particle inner in the form of inert Li2Si20s and SiO2 nanotubes to realize the.prelithiation.The degree of prelithiation can be regulated by adjusting the coating amount of LiNH2 layer,and the resulted M-Li-SiOx displays a prominent improvement of ICE from 58.73%to 88.2%.The graphite/M-Li-SiOx(8:2)composite electrode delivers a.discharge capacity of 497.29 mAh·g^(-1) with an ICE of 91.79%.By pairing graphite/M-Li-SiOx anode and LiFeP04 cathode in a full-cell an enhancement of energy density of 37.25%is realized compared with the full-cell containing graphite/SiOx anode.Furthermore,,ex-situ X-ray photoelectron spectroscopy(XPS)/Raman/X-ray diffraction(XRD)and related electrochemical measurements reveal the SiOx core and Si of M-Li-SiOx participate in the lithiation,and pre-generated Li2Si20s with u+diffusivity and pomegranate-like.structure reduces the reaction resistance and interface impedance of the solid electrolyte interphase(SEI)film.

关 键 词：initial Coulombic efficiency thermochemical prelithiation liquid coating MOLTEN-SALT mass transfer 

分 类 号：O64[理学—物理化学]