高界面能异质结构促进更大锂沉积和快速Li+去溶剂化 | Science Bulletin

Science Bulletin 2022年第24期封面文章报道了广东工业大学李成超教授课题组与厦门大学赵金保教授课题组合作的研究成果。

研究简介

高界面能电解液界面有助于更大的锂成核胚胎和更稳定的界面, 因此界面能对于高度可逆的锂沉积/剥离极为重要。广东工业大学李成超教授课题组与厦门大学赵金保教授课题组合作，设计了一种高界面能的人工固体电解质界面(SEI), 将丰富的LiF嵌入PAMPS-Li聚合物网络中, 同时实现有利的锂成核和快速Li⁺去溶剂化。LiF(001)中的Li−F键与Li原子有更强的离子偶极作用, 与其他成分相比具有更高的界面能。当锂生长表面能和总界面能达到平衡时, 具有丰富LiF的高界面能SEI可以促进更大的锂金属成核胚胎。此外, 将阴离子固定的PAMPS-Li与锂的相互作用较弱, 具有较高的聚合物-锂界面能, 其具有的酰胺基和磺酸基与Li⁺表现出更高的结合能。因此, 高界面能的PAMPS-Li可以促进Li⁺轻易地脱离溶剂鞘, 并减少解溶能垒。基于高界面能的异质结构SEI的协同改性, 实现了高度可逆的锂沉积行为, 并限制了副反应的发生。最重要的是, 具有低N/P比(1.67)的多层锂金属软包电池(330 Wh kg⁻¹)的循环寿命长达100次以上, 验证了其潜在的实际应用。

图文导读

Fig. 1. The function in metallic Li⁰ deposition and characterization of FCNTs@Li. 

(a) The schematic illustration for the roles of FCNTs@Li in metallic Li⁰ deposition. 

(b) The structure sketch map of FCNTs@Li during cycling. 

(c) and (d) The schematic illustration of fabrication and lithiation of FCNTs@Li, respectively. 

(e) and (f) The optical image of large-scale fabrication of FCNTs@Li system and sample, respectively. 

(g) and (h) The front-section and cross-section scanning electron microscope (SEM) images of FCNTs@Li, respectively.

Fig. 2. The electrode performance and metallic Li0 deposition morphology images of FCNTs@Li.

(a) The symmetry cell performance and zoomed-in images with current density of 1 mA cm⁻² and deposition capacity of 3 mAh cm⁻². 

(b) The symmetry cell performance at different rates (0.5, 1, 2, and 5 mA cm⁻²). 

(c) The symmetry cell performance when limited Li (50 μm thick) was applied. 

(d) The plot summarizing per-cycle areal capacity of the metallic Li0 (x-axis), cumulative areal plating capacity (y-axis), and current density (size of each circle) in this work and analogous publications using ester electrolyte.  

(e) The Tafel plots of pure Li and FCNTs@Li. 

(f), (g) The front-section and cross-section SEM images of pure Li and FCNTs@Li after 50 cycles, respectively.

(h), (i) In situ optical microscopy observation of metallic Li0 plating behavior of pure Li and FCNTs@Li with deposition rate of 0.5 mA cm⁻², respectively.

Fig. 3. DFT calculations of the metallic Li0 dendrite suppression mechanism by LiF-rich SEI formatted by FCNTs@Li.

(a) Atomic structures of LiF (001) facet and heterojunctions with LiF-Li, Li₂O-Li, and Li₂CO₃-Li. 

(b) Relationship between interfacial energy of common inorganic components in SEI with lithium and the number of lithium units. 

(c) Graphical illustration on impacts of SEI’s interfacial energy on metallic Li⁰ deposition. (d) Absorption of Li⁺ on the LiF, Li₂CO₃, and Li₂O. (e) Binding energy of Li⁺ with different solvent molecules and organic components in SEI formatted by FCNTs@Li. 

(f), (g), and (h) The DOS profiles by atomic layer with Fermi level at 0 eV of Li₂CO₃, Li₂O, and LiF, respectively.

Fig. 4. The SEI state analysis of metallic Li0 surface after cycling.

(a), (d) The C 1s, O 1s, F 1s, and Li 1s spectra of SEIs formed in pure Li and FCNTs@Li with different etching times, respectively. 

(b), (e) The changes in C, O, F and Li atomic concentrations with etching time in SEIs formed by pure Li and FCNTs@Li, respectively. 

(c), (f) The EISs of pure Li and FCNTs@Li after the initial cycle at 30–50 °C, respectively. 

(g) The activation energy of symmetrical cells with pure Li and FCNTs@Li obtained from the Arrhenius formula. 

(h) Schematic illustration for desolvation of Li+ on the pure Li (left) and FCNTs@Li (right). 

(i) The TOF-SIMS depth profiles of SEIs film formed by pure Li and FCNTs@Li. 

(j) The depth distributions of Li₂F⁻, LiO⁻, and OEC with etching time in SEI film. 

(k) The i-t curves of chronoamperometry of the FCNTs@Li symmetry cell.

Fig. 5. Comparison of NCM811 cull cell electrochemical performance in coin cell and pouch cell. 

(a) The NCM811 full cell electrochemical performance with the current density of 3.0 C (1.68 mA cm⁻²). 

(b), (c) The voltage-capacity retention curves of pure Li||NCM811 and FCNTs@Li||NCM811, respectively, during different cycles. 

The NCM811 full cell electrochemical performance with the current density of 1.0 C (3.2 mA cm⁻²) involves high loading NCM811 cathode (mass loading of 16.12 mg cm⁻², 3.2 mAh cm⁻²) and limited Li metal anode (thickness of 50 μm, 10 mAh cm⁻²), indicating that the N/P ratio is 3.1. 

(e) The definite structural relationship of the cathode electrode and anode electrode to the separator inside the Li metal pouch cell. 

(f) The NCM811 pouch cell electrochemical performance with the charge rates of 0.5 C (1.61 mA cm⁻²) and 0.1 C (0.32 mA cm⁻²). The embedded image is the optical photograph of assembled FCNTs@Li||NCM811 pouch cell with a capacity of 1.15 Ah. 

(g) Schematic diagram of Li metal pouch cell. 

(h) The plot for total capacities of the Li-metal pouch cell (x-axis), N/P ratio (y-axis), and the cycling number (z-axis) in this work and analogous publications assembled with lithium-containing cathodes (NCM or LFP).

文章信息

Zhipeng Wen, Yuanhong Kang, Qilong Wu, Xiu Shen, Pengbin Lai, Yang Yang, Cheng Chao Li, Jinbao Zhao. High interfacial-energy heterostructure facilitates large-sized lithium nucleation and rapid Li⁺ desolvation process. Science Bulletin, 2022,67(24): 2531-2540

https://doi.org/10.1016/j.scib.2022.11.026

长按识别二维码，阅读全文

相关阅读