Computational and experimental search for potential polyanionic K-ion cathode materials

Abstract

Discovering high-energy cathode materials is critical to construct K-ion batteries for practical applications. Owing to the great success of layered oxides in Li- and Na-ion system, K layered cathodes have...

Expanding the Material Search Space for Multivalent Cathodes

“…The computational exploration of six perovskites as Ca cathodes resulted in evaluating the Ca mobility in one composition identified as the most promising perovskite compound . A high-throughput computational screening methodology for layered materials has also been reported for sodium and multivalent cathodes, which included the calculation of migration barriers for ∼40 down selected layered materials. , A recent screening of polyanionic materials as K-ion cathodes used computational methods to down select candidate materials based on composition, stability, capacity, and voltage, at which point, four compounds were selected for experimental investigation . Potassium mobility was computationally investigated for one compound.…”

“…Cathode computational screenings that consider ionic mobility have typically used nudged elastic band (NEB) calculations in conjunction with DFT to estimate the migration barrier. ,,,,, NEB calculations are notoriously challenging due to the domain expertise required to inform the calculation inputs, their high computational cost, and numerical sensitivity that requires careful inspection of the calculation outputs. These challenges are evidenced by the number of cathode computational screenings that reserve performing NEB calculations for the single, most promising candidate, ,, exclude ionic mobility entirely, , or opt to pursue experimental electrochemical testing before performing a NEB calculation …”

“…23,24 A recent screening of polyanionic materials as K-ion cathodes used computational methods to down select candidate materials based on composition, stability, capacity, and voltage, at which point, four compounds were selected for experimental investigation. 25 Potassium mobility was computationally investigated for one compound. Across these efforts, there has been a fundamental limitation insomuch that only one structural family, where the diffusion pathway and intercalation sites are already known, is considered.…”

“…These challenges are evidenced by the number of cathode computational screenings that reserve performing NEB calculations for the single, most promising candidate, 19,22,26 exclude ionic mobility entirely, 17,18 or opt to pursue experimental electrochemical testing before performing a NEB calculation. 25 Given the challenges with NEB calculations, there have been several studies dedicated to acceleration efforts. The most common strategy to lower computational cost is reducing the number of image relaxations along the predicted pathway.…”

Review on Cathode Materials for Sodium‐ and Potassium‐Ion Batteries: Structural Design with Electrochemical Properties

“…The average voltage, specific capacity, and energy density of recently reported cathode materials are summarized in Figure 2 [46–108] . In the NIB system, layered oxide cathode was found to be more advantageous in overall electrochemical properties, including the gravimetric capacity and energy density.…”