Role of in-situ TEM in designing the ideal all-solid-state batteries

Abstract text (incl. figure legends and references)

Safety features of Li-ion batteries are a high priority requirement as their adoption in electric vehicles and day-to-day electronic devices is continuously increasing. The liquid electrolytes that are typically used in traditional Li-ion batteries are flammable, especially at higher operating voltages and temperatures. By contrast, an all-solid-state battery (ASSB) makes use of solid electrolyte instead of liquid electrolyte, which reduces the risk of flammability. However, the solid-solid electrolyte-electrode interface in ASSBs introduces different sets of challenges from the traditional liquid-solid electrode-electrolyte interface [1,2]. First, in batteries containing liquid electrolytes entire surface of electrode particles is wetted by electrolytes, whereas the electrode and solid electrolyte particles in ASSBs are connected primarily at point contacts, which are limited in terms of their numbers (as not all electrode particles are in direct contact with electrolyte particles), therefore ionic transport is basically restricted, diminishing the specific capacity of these batteries. Decomposition reactions at the electrode-electrolyte interfaces during battery cycling cause the formation of passivating layers and as well as electrode volume changes during battery cycling result in loss of contacts between electrode and electrolyte particles, further decreasing direct ion exchange pathways. Second, inhomogeneous (de)lithiation through point contacts can induce strain, which affects electrode mechanical integrity leading to capacity fade. Operando transmission electron microscopy (TEM) allows for the visualization of (de)lithiation processes in electrode materials at a single particle level in real-time. In our recent research, we have utilized the volume change property of Si nanoparticles during (de)lithiation to understand the interface kinetics [3] and the role of coatings [4] during cycling.

References:

[1] C. Yu et al. Accessing the bottleneck in all-solid-state batteries, lithium-ion transport over the solid-electrolyte-electrode interface. Nat. Commun. 2017. doi:10.1038/s41467-017-01187-y
[2] Q. Xu et al., Active Interphase Enables Stable Performance for an All‐Phosphate‐Based Composite Cathode in an All‐Solid‐State Battery. doi: 10.1002/smll.202200266
[3] S. Basak et al., Operando Transmission Electron Microscopy Study of All-Solid-State Battery Interface: Redistribution of Lithium among Interconnected Particles. ACS Appl. Energy Mater. 2020. doi:10.1021/acsaem.0c00543
[4] S.Basak et al., Operando transmission electron microscopy of battery cycling: thickness dependent breaking of TiO2 coating on Si/SiO2 nanoparticles. Chem. Commun., 2022, 58, 3130-3133. doi:10.1039/D1CC07172F