Three-dimensional visualization of lithium metal anode via low-dose cryogenic electron microscopy tomography

Xiangyan Li,Bing Han,Xuming Yang,Zhipeng Deng,Yucheng Zou,Xiaobo Shi,Liping Wang,Yusheng Zhao,Sudong Wu,Meng Gu

doi:10.1016/j.isci.2021.103418

Abstract

SummaryThe structure of lithium (Li) metal anode, including the Li metal and the solid electrolyte interphase (SEI), is critical to the investigation of cycle stability or decay mechanisms. The three-dimensional (3D) visualization of Li metal and SEI, however, has not been demonstrated yet, owing to the lack of 3D characterization techniques and the susceptibility of Li metal anode toward oxygen, moisture, as well as electron beam. Herein, we introduce a successful 3D presentation of deposited Li metal and SEI established via low-dose cryogenic electron microscopy tomography. The Li metal anode is imaged in low-dose mode at different tilt angles and then aligned and reconstructed into a 3D image through an expectation-maximization algorithm. The spherical Li deposits and SEI are confirmed in the 3D tomography of Li metal anode. It is also discovered that the Li metal corrodes and SEI turns concave owing to possible self-discharge after long-time rest.

Highlights

The rapid growth of electric vehicle markets and smart grid implementation creates an urgent need for developing batteries with high energy density and long calendar life (Alper, 2002; Dunn et al, 2011)
We introduce a successful 3D presentation of deposited Li metal and solid electrolyte interphase (SEI) established via low-dose cryogenic electron microscopy tomography
The spherical Li deposits and SEI are confirmed in the 3D tomography of Li metal anode

Summary

Introduction

The rapid growth of electric vehicle markets and smart grid implementation creates an urgent need for developing batteries with high energy density and long calendar life (Alper, 2002; Dunn et al, 2011). The energy density of commercial lithium (Li)-ion batteries has been significantly improved in the past decades, and it is already very close to their ceiling values (Yang et al, 2020). Further substantial increase in energy density will necessarily depend on innovation on new electrode materials, and one typical case is Li metal anode (Shi et al, 2018; Zhang et al, 2018). The replacement of graphite anode with Li metal will undoubtedly help to achieve higher energy density, and it will allow the use of Li-free cathode materials to make batteries with much higher capacity, such as lithium-sulfur batteries (Jiang et al, 2021; Lin et al, 2021; Manthiram et al, 2014). Solid electrolyte interphase (SEI), which is usually formed during initial cycles, can passivate the surface of Li metal but allow the passage of Li ions (Goodenough and Kim, 2009; Peled et al, 1995)

Results

Discussion

Conclusion