With the ultra-high capacity (3860 mAh ·g^-1) and the most negative electrochemical potential (-3.040 V vs the standard hydrogen electrode), lithium metal is regarded as a "Holy Grail" electrode and has received extensive attentions. Therefore, lithium metal based batteries (such as lithium-sulfur and Li-oxygen batteries) are strongly considered as one of the most promising candidates for the next-generation high-energy-density energy storage devices. However, uncontrolled dendritic-lithium growth results in poor cycling efficiency, severe safety concerns, and poor lifespan, which severely prevents the practical applications of Li metal based batteries. This contribution presents a comprehensive overview on the dendrite issues of lithium metal anode. Firstly, the general working principles and technical challenges of lithium metal anode are introduced. Specific attentions are also paid to the mechanistic understandings and quantitative models for the nucleation and growth of dendritic lithium. Based on these theoretical understanding and analysis, the recently proposed methods to suppress dendrite growth of lithium metal anode are summarized. The perspective on the current limitations and future research directions of LMB are presented. The review is with an attempt at summarizing the theoretical and experimental achievements in lithium metal anode and endeavors to realize the practical applications of lithium metal based batteries.
Contents
1 Introduction
2 Intrinsic property of Li metal anode
2.1 Thermodynamic nature of Li metal anode
2.2 Role of dendrite growth on Li metal anode
3 Models for dendrite growth
3.1 Surface nucleation and diffusion model
3.2 Heterogeneous nucleation model
3.3 Space charge model
3.4 SEI-induced-growth model
3.5 Sand's time model
4 Strategies to suppress dendrite growth
4.1 Liquid electrolyte modification
4.2 Highly concentrated electrolyte
4.3 Nanostructured electrolyte
4.4 Solid-state electrolyte
4.5 Structured electrolyte
5 Conclusion and outlook