Li metal is an ideal anode material for next-generation energy storage devices due to its extremely high theoretical specific capacity and the lowest negative electrochemical potential [1,2]. However, uncontrolled Li dendrite growth and the side reaction between Li metal and electrolytes have prevented its practical application in rechargeable Li metal batteries. In our contributions, artificial solid electrolyte interphase (SEI) layer and 3D current collector have been developed to address these issues [3,4].

In this presentation, we will introduce an artificial Li₃PO₄ SEI layer [3] fabricated by in situ reaction of polyphosphoric acid (PPA) with Li metal and its native film (Li₂CO₃, LiOH, and Li₂O). The partial dissolution of the Li native film and formation of the SEI layer lead to a porous structure of the Li surface, thereby promoting Li dendrite formation and growth. In the ingenious design, the native film of Li metal is replaced by the stable and uniform Li₃PO₄ SEI layer. The artificial Li₃PO₄ SEI layer with thickness of 50 nm exhibits a smooth surface and a high Young’s modulus (10-11 GPa). Furthermore, the artificial Li₃PO₄ SEI layer is demonstrated to be stable in the electrolyte and during cycling in a Li|LiFePO₄ battery system. The Li-conducting Li₃PO₄SEI layer can achieve uniform Li deposition, and reduce the side reaction between the Li metal and the electrolyte. Thus, the artificial SEI strategy we described is a promising route to tackle the intrinsic problems of Li metal anodes and other metal based anodes.

Furthermore, we will show that Li metal anode can be accommodated in the reserved pores of the 3D current collector [4] with a submicron skeleton and high surface area, thereby suppressing the Li dendrite growth and solving the associated problems of Li metal anodes. Because of the high electroactive area of the submicron 3D structure, the 3D current collector can improve the Li plating/stripping efficiency and reduce the resistance of the Li metal anode. The utilization of the 3D architecture to accommodate the Li metal anode will highlight the importance of rational design of current collectors and reveal a new avenue for developing Li metal anodes with a long lifespan.

References

1. Y.-X. Yin, S. Xin, Y.-G. Guo, L.-J. Wan, Angew. Chem. Int. Ed. 2013, 52, 13186.
2. W. Xu, J. L. Wang, F. Ding, X. L. Chen, E. Nasybutin, Y. H. Zhang, J. G. Zhang, Energ. Environ. Sci. 2014, 7, 513.
3. N.-W. Li, Y.-X. Yin, C.-P. Yang, Y.-G. Guo, Adv. Mater. 2015, DOI: 10.1002/adma.201504526.
4. C.-P. Yang, Y.-X. Yin, S.-F. Zhang, N.-W. Li, Y.-G. Guo, Nat. Commun. 2015, 6, 8058