Wang Zhenxing, Sun Zhenhua, Li Juan, Shi Ying, Sun Chengguo, An Baigang, Cheng Hui-Ming, Li Feng
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.
School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China.
Chem Soc Rev. 2021 Mar 15;50(5):3178-3210. doi: 10.1039/d0cs01017k.
Lithium (Li) is the lightest and most electronegative metallic element and has been considered the ultimate anode choice for energy storage systems with high energy density. However, uncontrollable dendrite formation caused by high ion transfer resistance and low Li atom diffusion, and dendrite growth with large volume expansion and high electronegative activity, result in severe safety concerns and poor coulombic efficiency. In this review, the latest progress is presented from the viewpoint of dendrite evolution (from dendrite formation to growth) as the main line to understand the factors that influence the deposition chemistry. For the dendrite formation, specific attention is focused on the four distinct but interdependent factors: (a) how the dielectric constant, donor number, viscosity and salt concentration affect the movement of solvated Li+ in nonaqueous electrolyte. (b) The effect of non-polar solvents and anions with polar groups or high concentration on the Li+ desolvation step. (c) The effect of the formation of solid electrolyte interphase (SEI), along with its specific adsorption and solvated structure, and its physical structure, chemical composition and growth thickness on Li+ diffusion. (d) The effect of the diffusion coefficient of the host material on Li atom migration. After dendrite formation, the attention is focused on two detrimental factors together with dendrite growth: (e) low coulombic efficiency; (f) large volume expansion. Correspondingly, the emphasis is placed on reducing the side reactions and minimizing the volume expansion. Conclusions and perspectives on the current limitations and future research directions are recommended. It is anticipated that the dynamic dendrite evolution can provide fresh insight into similar electrochemical reaction processes of other anode chemistries in nonaqueous electrolytes, ranging from a conversion-reaction metal anode (Li, Na, Al) and an alloying anode (LiAlx, NaAlx) to an intercalation-based anode (graphite, TiS2), as well as aqueous, ionic liquid and flow redox battery systems.
锂（Li）是最轻且电负性最强的金属元素，一直被视为具有高能量密度的储能系统的终极阳极选择。然而，高离子转移电阻和低锂原子扩散导致的不可控枝晶形成，以及枝晶生长时伴随的大量体积膨胀和高电负性活性，引发了严重的安全问题并导致库仑效率低下。在本综述中，以枝晶演变（从枝晶形成到生长）为主线介绍了最新进展，以了解影响沉积化学的因素。对于枝晶形成，特别关注四个不同但相互依存的因素：（a）介电常数、给体数、粘度和盐浓度如何影响非水电解质中溶剂化Li⁺的移动。（b）非极性溶剂以及具有极性基团或高浓度的阴离子对Li⁺去溶剂化步骤的影响。（c）固体电解质界面（SEI）的形成及其特定吸附和溶剂化结构，以及其物理结构、化学成分和生长厚度对Li⁺扩散的影响。（d）主体材料的扩散系数对锂原子迁移的影响。枝晶形成后，关注点集中在与枝晶生长相关的两个有害因素上：（e）库仑效率低；（f）大量体积膨胀。相应地，重点在于减少副反应并使体积膨胀最小化。文中还给出了关于当前局限性和未来研究方向的结论与展望。预计动态枝晶演变可为非水电解质中其他阳极化学的类似电化学反应过程提供新的见解，这些过程包括从转换反应金属阳极（Li、Na、Al）和合金阳极（LiAlₓ、NaAlₓ）到基于嵌入的阳极（石墨、TiS₂），以及水性、离子液体和液流氧化还原电池系统。
