Regulating Li Nucleation and Growth Heterogeneities via Near-Surface Lithium-Ion Irrigation for Stable Anode-Less Lithium Metal Batteries

Abstract

The inhomogeneous nucleation and growth of Li dendrite combined with the spontaneous side reactions with the electrolytes dramatically challenge the stability and safety of Li metal anode (LMA). Despite tremendous endeavors, current success relies on the use of significant excess of Li to compensate the loss of active Li during cycling. Herein, a near-surface Li+ irrigation strategy is developed to regulate the inhomogeneous Li deposition behavior and suppress the consequent side reactions under limited Li excess condition. The conformal polypyrrole (PPy) coating layer on Cu surface via oxidative chemical vapor deposition technique can induce the migration of Li+ to the interregional space between PPy and Cu, creating a near-surface Li+-rich region to smooth diffusion of ion flux and uniform the deposition. Moreover, as evidenced by multiscale characterizations including synchrotron high-energy X-ray diffraction scanning, a robust N-rich solid-electrolyte interface (SEI) is formed on the PPy skeleton to effectively suppress the undesired SEI formation/dissolution process. Strikingly, stable Li metal cycling performance under a high areal capacity of 10 mAh cm-2 at 2.0 mA cm-2 with merely 0.5 x Li excess is achieved. The findings not only resolve the long-standing poor LMA stability/safety issues, but also deepen the mechanism understanding of Li deposition process. A conformal lithiophilic polypyrrole thin layer is coated on Cu surface via oxidative chemical vapor deposition to induce the formation of near-surface Li+-rich region. The increased interface Li+ density can suppress the nucleation and diffusion heterogeneity to regulate the Li deposition behavior. The construction of robust N-rich solid-electrolyte interface (SEI) derived from the conformal polypyrrole skeleton can also effectively improve interfacial stability.image