An Artificial Solid Electrolyte Interphase Layer for Stable Lithium Metal Anodes
An Artificial Solid Electrolyte Interphase Layer for Stable Lithium Metal Anodes
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DOI：
10.1002/adma.201504526
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发表时间：
2016-03-02
影响因子：
29.4
通讯作者：
Guo, Yu-Guo
中科院分区：
文献类型：
--
作者：
Li, Nian-Wu;Yin, Ya-Xia;Guo, Yu-Guo
DOI：10.1002/adma。 201504526 在有机溶剂中不稳定，在液体溶液中实现Li表面的充分钝化是困难的。最近，固态电解质保护膜[11]碳基中间层[12]已被用作锂金属阳极或硅阳极中的稳定界面层。然而，正如 Aurbach 及其同事所指出的，[13] 在实际的锂金属电池中，原生膜（Li 2CO 3、LiOH 和 Li 2O）的部分溶解和 SEI 层的形成导致了多孔结构，其中锂离子通量局部增强，从而促进了锂枝晶的形成和生长。 [6a, 8c, 13b] 去除原生膜的不稳定成分，同时 同时形成稳定的SEI层是很困难的。为了解决这些问题，我们通过多磷酸（PPA）与锂金属及其原生薄膜的原位反应设计了人造Li 3PO 4 SEI层（方案1）。均匀的Li 3PO 4 SEI层被证明在电解质中和Li|循环过程中是稳定的。没有破损/修复机制的 LiFePO 4 电池系统。因此，均匀的Li 3PO 4 SEI层可以抑制Li金属与电解质之间的不利反应。此外，Li 3PO 4 层可以增强Li金属界面和电解质之间的锂离子传输。因此，可以抑制Li|中的Li枝晶生长。 LiFePO 4 电池系统。为了获得均匀的人工SEI层，低湿度和反应时间控制是必要的。少量水分，包括二甲基亚砜 (DMSO) 溶液中的水分，以及使用 85 wt% H3po 4 作为溶质（图 S1a-d，支持信息），可能会导致表面粗糙。虽然PPA可以吸附DMSO溶液中的水分并生成H3po 4，但高纯度的DMSO（> 99.9%）是必要的。较长的反应时间也会导致多孔且粗糙的界面（图 S1e、f，支持信息）。正如扫描电子显微镜（SEM）图像（图1a，b）所示，锂金属的表面是光滑的。虽然氧均匀分布在Li金属表面（图1d），但碳分布不均匀（图1c），表明Li 2CO 3 在Li金属表面分布不均匀。用PPA溶液处理Li金属后，所得PPA-Li具有光滑均匀的表面（图1e，f），磷和氧均匀分布在其上（图1g，h）。采用氩离子溅射技术的X射线光电子能谱（XPS）来检测PPA-Li阳极的深度剖面信息（图1i）。尽管SEM检测到的人造SEI层可达约200 nm（图S2，支持信息），但100、150、200 nm深度处的人造SEI层的主要成分是锂金属。因此，人工SEI层的有效厚度约为50 nm。采用原子力显微镜（AFM）的峰值力敲击（PFT）模式[14]测量PPA-Li负极的形貌和杨氏模量（图1k）。迫切需要先进的储能系统来满足消费电子、电动汽车和电网存储不断增长的需求。[1]可充电锂金属电池被认为是储能系统的“圣杯”，因为锂金属具有极高的理论比容量（3860 mA hg−1）和最低的负电化学势（相对于标准氢电极−3.04 V）。 [2]然而，由于锂金属沉积/溶解不均匀以及锂金属与电解质之间的副反应，可充电锂金属电池尚未商业化。 [3]由于其高反应性，Li ...
DOI: 10.1002/adma. 201504526 unstable in organic solvents, achieving sufficient passivation of the Li surface in liquid solutions is difficult. Recently, solid-state electrolyte protection film,[11] carbonbased interlayers [12] have been used as stable interface layers in the Li metal anode or silicon anode. However, as indicated by Aurbach and co-workers,[13] in a practical Li metal battery, the partial dissolution of the native film (Li 2CO 3, LiOH, and Li 2O) and formation of the SEI layer lead to a porous structure where the Li ionic flux is locally enhanced, thereby promoting Li dendrite formation and growth.[6a, 8c, 13b] Removing the unstable composition of the native film while simultaneously forming a stable SEI layer is difficult. To address these issues, we designed an artificial Li 3PO 4 SEI layer (Scheme 1) by in situ reaction of polyphosphoric acid (PPA) with Li metal and its native film. The uniform Li 3PO 4 SEI layer was demonstrated to be stable in the electrolyte and during cycling in Li| LiFePO 4 battery systems without a breakage/repair mechanism. Thus, the uniform Li 3PO 4 SEI layer can restrain the unfavorable reaction between the Li metal and the electrolyte. Furthermore, the Li 3PO 4 layer can enhance Li-ion transport between the Li metal interface and the electrolyte. Thus, Li dendrite growth can be restrained in Li| LiFePO 4 battery systems. To obtain a uniform artificial SEI layer, low moisture and reaction time control are necessary. A small amount of moisture, including the moisture in the dimethylsulfoxide (DMSO) solution, and using the 85 wt% H3po 4 as the solute (Figure S1a–d, Supporting Information), can lead to a rough surface. Although PPA can adsorb the moisture in the DMSO solution and generate H3po 4, high-purity DMSO (> 99.9%) is necessary. A long reaction time can also lead to a porous and rough interface (Figure S1e, f, Supporting Information). As shown in the scanning electron microscopy (SEM) images (Figure 1a, b), the surface of the Li metal is smooth. Although the oxygen is uniformly distributed on the surface of the Li metal (Figure 1 d), the carbon is nonuniformly distributed (Figure 1 c), indicating that Li 2CO 3 has a nonuniform distribution on the surface of the Li metal. After treatment of the Li metal with PPA solution, the resulting PPA-Li has a smooth and uniform surface (Figure 1 e, f) on which phosphorus and oxygen are uniformly distributed (Figure 1 g, h). The X-ray photoelectron spectroscopy (XPS) with argon-ion sputtering technology was employed to detect the depth profile information of the PPA-Li anode (Figure 1 i). Although the artificial SEI layer can be up to≈ 200 nm detected by SEM (Figure S2, Supporting Information), the dominant composition of artificial SEI layer at depth of 100, 150, 200 nm is Li metal. Thus, the effective thickness of the artificial SEI layer is≈ 50 nm. The peak force tapping (PFT) mode [14] of the atomic force micro scopy (AFM) was employed to measure the morphology and the Young’s modulus of PPA-Li anode (Figure 1 k).Advanced energy storage systems are urgently needed to satisfy the continuously surging demand in consumer electronics, electric vehicles, and grid storage.[1] Rechargeable Li metal batteries are considered the “Holy Grail” of energy storage systems because Li metal has an extremely high theoretical specific capacity (3860 mA hg− 1) and the lowest negative electrochemical potential (− 3.04 V versus the standard hydrogen electrode).[2] However, rechargeable Li metal batteries have not yet been commercialized because of the uneven deposition/dissolution of Li metal and the side reaction between Li metal and electrolytes.[3] Because of its highly reactive nature, Li …