Interface Aspects in All‐Solid‐State Li‐Based Batteries Reviewed

Abstract

Extensive efforts have been made to improve the Li‐ionic conductivity of solid electrolytes (SE) for developing promising all‐solid‐state Li‐based batteries (ASSB). Recent studies suggest that minimizing the existing interface problems is even more important than maximizing the conductivity of SE. Interfaces are essential in ASSB, and their properties significantly influence the battery performance. Interface problems, arising from both physical and (electro)chemical material properties, can significantly inhibit the transport of electrons and Li‐ions in ASSB. Consequently, interface problems may result in interlayer formation, high impedances, immobilization of moveable Li‐ions, loss of active host sites available to accommodate Li‐ions, and Li‐dendrite formation, all causing significant storage capacity losses and ultimately battery failures. The characteristic differences of interfaces between liquid‐ and solid‐type Li‐based batteries are presented here. Interface types, interlayer origin, physical and chemical structures, properties, time evolution, complex interrelations between various factors, and promising interfacial tailoring approaches are reviewed. Furthermore, recent advances in the interface‐sensitive or depth‐resolved analytical tools that can provide mechanistic insights into the interlayer formation and strategies to tailor the interlayer formation, composition, and properties are discussed.

Nano‐Scale Complexions Facilitate Li Dendrite‐Free Operation in LATP Solid‐State Electrolyte

“…From this contrast three regions can be differentiated: the crystalline LATP grains, thin and darker semi-amorphous regions to both sides at the crystalline grain interface, and a brighter amorphous region in the grain boundary center. Both grains are oriented in [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] hex zone axis. The highly symmetric bright reflexes in Figure 1c correspond to a [100] pc pseudocubic sublattice commonly assigned to partially occupied Li positions in the LATP crystal structure.…”

“…This is mainly due to mechanochemical, chemical, and electrochemical stability issues and interfacial processes that have severely compromised any proposed cell's lifetime. [7][8][9][10][11] While many SSE material inherent (mechano-)chemical processing issues seem amenable to modern engineering approaches, [12][13][14][15][16][17][18][19] the situation is less bright regarding the control of interfacial chemical and electrochemical stability (especially when featuring a LMA), as well as ionic and electronic transport quantities across these interfaces. A hitherto missing deep understanding of the structural, chemical, and physical properties of the buried solid-solid interfaces inside ASSBs at the atomic level is required to overcome these performance limiting interfacial issues.The most studied interfacial properties so far are contact stability and dendrite nucleation and growth.…”

Cryo‐Electron Microscopy for Unveiling the Sensitive Battery Materials

“…[ 25,26 ] In addition, both the solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI) on electrode surface are in a metastable state, and significantly affected by the air and electron beam. [ 27 ] Although a great deal of research has been done to understand their physical and chemical properties, [ 15,28 ] it is still challenging to directly observe the interface structure and gather the intrinsic information of electrode materials, especially at the nanoscale.…”

A Review of Existing and Emerging Methods for Lithium Detection and Characterization in Li‐Ion and Li‐Metal Batteries

“…[8] Additionally, tailoring the anode-electrolyte interface to mitigate formation of Li dendrites using strategies such as adding coatings is being explored. [196,197] Charging current densities have been achieved above the long-withstanding challenge of 1 mA cm −2 . However, significant improvement is still needed to enable XFC (>10 mA cm −2 ) current densities.…”