Impact of Electronic Properties of Grain Boundaries on the Solid Electrolyte Interphases (SEIs) in Li-ion Batteries

Abstract

Electron leakage through the solid-state electrolyte interphase (SEI) in Li-ion batteries causes the reduction of the electrolyte and the consumption of Li-ions, decreasing the battery capacity and performance. Given the multicomponents and mosaic structures of SEI, the extended defects such as grain boundaries (GBs) and interfaces in SEI are likely to serve as the electron conduction pathways, as the individual SEI components are wide-bandgap insulators in their single-crystalline forms. In this work, the electronic properties of representative GBs of the main SEI components (LiF, Li 2 O, and Li 2 S) on the Li-metal in various electrolytes were investigated via density functional theory (DFT) calculations. It was found that all the GB structures have smaller bandgaps than their corresponding single crystals, with an order of amorphous GBs < Tilt GBs < Twist GBs < single crystals. Some GBs, such as the symmetric Li 2 S Tilt ∑3 (1̅ 21̅ )/[111] GB and the amorphous LiF GB, showed empty electronic states lower than the standard Li + /Li 0 depositing potential. These GB states can trap electrons from the Li-metal, contributing to Li-dendrite growth and electron leakage through SEI. Structural analysis revealed that more under-coordinated atoms in the GBs led to smaller bandgaps and more excess electron localization in the less dense GB regions. These insights suggested that dense SEI structures such as sharp interfaces and well-ordered GBs are preferred to design a fully electronically passivating SEI.

Operating High‐Energy Lithium‐Metal Pouch Cells with Reduced Stack Pressure Through a Rational Lithium‐Host Design

“…This is potentially because the electron‐conducting defects on the LSnS powder surface were largely passivated by poly(PETEA). [ 55,56 ]…”

“…This is potentially because the electron-conducting defects on the LSnS powder surface were largely passivated by poly(PETEA). [55,56] The instability of solid electrolyte against reduction is a predominant cause for cell failure and becomes significant when a high-surface-area conductive substrate is in use. [57] According to the cyclic voltammetry (CV) profile in Figure 2e, the LSnS/C electrode displays visible cathodic redox peaks (located at 1.7 and 0.95 V), which originate from the multiple-step solid electrolyte decomposition processes (1.7 V: reduction of Li 4 SnS 4 to from Li 2 SnS 2 and Li 2 S; 0.95 V: reduction of Li 2 SnS 2 to form Sn and Li 2 S).…”

Li+ Ion Transport at the Lithium Metal Anode: A Fundamental Picture and Future Perspectives

“…While enhancing ionic transport is beneficial, DFT calculations by Smeu and Leung show that highly heterogeneous SEIs enhance electron tunneling, which can allow electron leakage that leads to further electrolyte degradation and battery breakdown . Further calculations by Qi and co-workers revealed that the fine structure of the GBs determines the ability of LiF to retain its insulating electronic structure . Amorphous LiF GBs, notably, generate unoccupied states below the Li + /Li 0 potential that can induce dendrite growth.…”

Nano and Battery Anode: A Review

“…6 (SEM image). In this way, the problem of crushing can be solved, because there is enough space between the nanowires to change the volume of each nanowire during the duty cycle without generating extensive stress, the diameter of each nanowire is also less than the critical dimension [ 19 – 22 , 30 , 54 – 56 ]. As it is known, after alloying (entry of lithium), the width of the nanowires increased and the side walls became textured, and although there was a large volume change, no fragmentation occurred [ 57 ].…”

“…In the latter method, the crystalline direction and doping can be easily controlled, and the effect of different dopants and crystalline directions on lithium storage can be determined [23,[82][83][84][85][86][87][88]. Even a nanomaterial with a specific shape and composition can be used in different ways and even in a specific method, different reactants can be used with different temperature conditions, etc., each of which may have different results in terms of price, safety and since the key to commercialization other than investing is to find the right production method by considering the factors listed above, so there is an inseparable link between production and performance in batteries and very good and appropriate articles Available in connection with the synthesis method [30,31,56,57,[89][90][91][92]. In addition to onedimensional nanostructures (nanowires and nanotubes), efforts have been made to use zero-dimensional nanostructures (nanoparticles) (as a good nanoparticle are easier to synthesize than nanowires).…”