Enabling Atomic‐Scale Imaging of Sensitive Potassium Metal and Related Solid Electrolyte Interphases Using Ultralow‐Dose Cryo‐TEM

Abstract

Potassium‐based solid electrolyte interphases (SEIs) have a much smaller damage threshold than their lithium counterpart; thus, they are significantly more beam sensitive. Here, an ultralow‐dose cryogenic transmission electron microscopy (cryo‐TEM) technique (≈8 e Å−2 s−1 × 10 s), which enables the atomic‐scale chemical imaging of the electron‐beam‐sensitive potassium metal and SEI in its native state, is adapted. The potassium‐based SEI consists of large brackets of diverse inorganic phases (≈hundreds of nanometers) interspersed with amorphous phases, which are different from the tiny nanocrystalline inorganic phases (≈a few nanometers) formed in a lithium‐based SEI. Organic phosphate‐based electrolyte solvents induce the formation of a thin and stable SEI layer for enhanced cycling performance, while the carbonate ester‐based electrolytes result in large quantities of metastable KHCO3, and K4CO4 products in the SEI, depleting the potassium reserves in the battery. The findings provide deep insights and guidance in the selection of optimum electrolytes that should be used for potassium batteries.

Cryo‐Electron Tomography of Highly Deformable and Adherent Solid‐Electrolyte Interphase Exoskeleton in Li‐Metal Batteries with Ether‐Based Electrolyte

“…direct electron detection cameras can cool down the sample to ≈−193 °C, which allows us to probe the fine details of Li Metal and SEI at the atomic scale. [10][11][12][13][14][15][16][17][18][19][20] The reductive decomposition of electrolyte was believed to result in surficial passivation layer (SEI exoskeleton) on the anode. [21][22][23] Here, we observe that some components of the SEI exoskeleton can be found on the surface of plated inner crystalline Li BCC as well.…”

Enabling Ultrastable Alkali Metal Anodes by Artificial Solid Electrolyte Interphase Fluorination

“…In the pursuit of next-generation high-energy-density batteries, alkali-based metal anodes offer compelling advantages in capacity and voltage. Lithium (Li) anodes have both a high specific capacity (3860 mAh g –1 ) and the lowest working voltage (−3.04 V vs standard hydrogen electrode), − but sodium (Na) and potassium (K) anodes have similar plating/stripping mechanisms − and represent promising cost-effective alternatives. − However, the adoption of these alkali metal anodes is plagued with dendrite growth, which often results in low Coulombic efficiency (CE), and irrecoverable capacity loss, as well as a safety hazard related with separator penetration. The high reactivity of the alkali metal toward electrolytes could give rise to continuous electrolyte decomposition and severe pulverization, which would further promote uncontrollable dendrite nucleation and growth. , …”

Fe3+-Derived Boosted Charge Transfer in an FeSi4P4 Anode for Ultradurable Li-Ion Batteries

“…More specifically, the electrode materials were carefully detached from the Cu foil and dispersed in ethanol for 0.5–1 h using a sonicator to separate the aggregated particles. Subsequently, the solution was slowly dropped on Formvar/Carbon 200 mesh Cu TEM grids (TED PELLA, INC.) and dried inside a vacuum oven (at 50 °C) for 1 h. The grids were conveyed in airtight foil/poly bags (Sigma-Aldrich) to avert unwanted reactions in air. − Continuous-wave EPR was recorded using a Bruker EMXplus spectrometer in the X band at a temperature of 4 K with a microwave frequency of 9.64 GHz, power of 1 mW, modulation frequency of 100 kHz, and modulation amplitude of 10 G. The intensities of all the samples were normalized by their mass. The g value was calculated using the following equation where h , v , β e , and B 0 denote the Planck constant, frequency, Bohr magneton, and resonance magnetic field, respectively. ,, The XPS data were collected on a K-alpha (Thermo Scientific Inc.) instrument using monochromated Al Kα radiation.…”