Microscopic observations of the formation, growth and shrinkage of lithium moss during electrodeposition and dissolution

Abstract Lithium electrodeposition and -dissolution in a commercial battery electrolyte (1 M LiPF 6 in EC:DMC) has been studied in situ by light microscopy and ex situ by scanning electron microscopy (SEM). We describe the transition between lithium filaments, which are most likely whiskers, and lithium moss and report in detail on the growth of mossy lithium structures. In the case of mossy lithium, the deposition can occur at the tips or the base of the growing structure. However, the growth is not limited to these locations, but can also occur by insertion at further growth points distributed inside the mossy Li deposit. We show that two different growth modes have to be distinguished: the unusual non-tip-growth by lithium metal insertion into the metallic moss backbone, and the condition where the deposition at the top of the mossy structure is not possible anymore because it was electrically isolated from the current collector due to a previous lithium dissolution step. After a dissolution period causing insulation of Li (“dead Li”), whole moss remnants can get pushed outside by metal structures growing underneath.

[1]  John P. Sullivan,et al.  Lithium Fiber Growth on the Anode in a Nanowire Lithium Ion Battery During Charging , 2011 .

[2]  Lithium Electrode Morphology during Cycling in Lithium Cells , 1988 .

[3]  J. Steiger,et al.  Mechanisms of dendritic growth investigated by in situ light microscopy during electrodeposition and dissolution of lithium , 2014 .

[4]  D. Aurbach,et al.  Impedance spectroscopy of lithium electrodes , 1994 .

[5]  Joachim Maier,et al.  Second Phase Effects on the Conductivity of Non‐Aqueous Salt Solutions: “Soggy Sand Electrolytes” , 2004 .

[6]  P. Willmann,et al.  Correlation between cycling efficiency and surface morphology of electrodeposited lithium. Effect of fluorinated surface active additives , 1996 .

[7]  Masahiro Ichimura,et al.  Lithium electrode cycleability and morphology dependence on current density , 1993 .

[8]  Alan C. West,et al.  Effect of Electrolyte Composition on Lithium Dendrite Growth , 2008 .

[9]  Myung-Hyun Ryou,et al.  Excellent Cycle Life of Lithium‐Metal Anodes in Lithium‐Ion Batteries with Mussel‐Inspired Polydopamine‐Coated Separators , 2012 .

[10]  T. Homma,et al.  In Situ Observation of Dendrite Growth of Electrodeposited Li Metal , 2010 .

[11]  Charles W. Monroe,et al.  Dendrite Growth in Lithium/Polymer Systems A Propagation Model for Liquid Electrolytes under Galvanostatic Conditions , 2003 .

[12]  P. Bro,et al.  Some Observations on Rechargeable Lithium Electrodes in a Propylene Carbonate Electrolyte , 1974 .

[13]  J. Maier,et al.  Soggy-sand electrolytes: status and perspectives. , 2013, Physical chemistry chemical physics : PCCP.

[14]  Shengbo Zhang.  A review on electrolyte additives for lithium-ion batteries , 2006 .

[15]  Noboru Oyama,et al.  Inhibition effects of polyacrylonitrile gel electrolytes on lithium dendrite formation , 1999 .

[16]  P. Meakin.  Formation of fractal clusters and networks by irreversible diffusion-limited aggregation , 1983 .

[17]  W. Pichl.  Recrystallization of Partially Transformed Lithium Single Crystals , 1996 .

[18]  J. Yamaki,et al.  A consideration of the morphology of electrochemically deposited lithium in an organic electrolyte , 1997 .

[19]  Doron Aurbach,et al.  A short review of failure mechanisms of lithium metal and lithiated graphite anodes in liquid electrolyte solutions , 2002 .

[20]  B. Liaw,et al.  A review of lithium deposition in lithium-ion and lithium metal secondary batteries , 2014 .

[21]  Emanuel Peled,et al.  The Electrochemical Behavior of Alkali and Alkaline Earth Metals in Nonaqueous Battery Systems—The Solid Electrolyte Interphase Model , 1979 .

[22]  L. Sander,et al.  Diffusion-limited aggregation, a kinetic critical phenomenon , 1981 .

[23]  Yasuhiro Fukunaka,et al.  Optical observation of Li dendrite growth in ionic liquid , 2013 .

[24]  Reza S. Yassar,et al.  Real-time observation of lithium fibers growth inside a nanoscale lithium-ion battery , 2011 .

[25]  Yasuhiro Fukunaka,et al.  Li dendrite growth and Li+ ionic mass transfer phenomenon , 2011 .

[26]  Ji‐Guang Zhang,et al.  Lithium metal anodes for rechargeable batteries , 2014 .

[27]  F. Lange,et al.  New class of soft matter electrolytes obtained via heterogeneous doping: Percolation effects in “soggy sand” electrolytes , 2006 .