Unraveling the reaction mechanisms of electrode materials for sodium‐ion and potassium‐ion batteries by in situ transmission electron microscopy

Abstract

Sodium ion batteries (SIBs) and potassium ion batteries (PIBs) have caught numerous attention due to the low cost and abundant availability of sodium and potassium. However, their power density, cycling stability and safety need further improvement for practical applications. Investigations on the reaction mechanisms and structural degradation when cycling are of great importance. In situ transmission electron microscopy (TEM) is one of the most significant techniques to understand and monitor electrochemical processes at an atomic scale with real-time imaging. In this review, the current progress in unraveling reaction mechanisms of electrode materials for SIBs and PIBs via in situ TEM is summarized. First, the importance of in situ TEM is highlighted. Then, based on the three types of electrochemical reaction, i.e., intercalation reaction, conversion reaction and alloying reaction, the structural evolution and reaction kinetics at atomic resolution, and their relation to the electrochemical performance of electrode materials are reviewed and described in detail. Finally, future directions of in situ TEM for SIBs and PIBs are proposed. Therefore, the in-depth understanding revealed by in situ TEM will give an instructive guide in rational design of electrode materials for high performance electrode materials of SIBs and PIBs.

Mesoporous Carbon-Based Materials: A Review of Synthesis, Modification, and Applications

“…Among them, mesoporous carbon structures with a broad or narrow distribution of pores have recently attracted enormous attention in different fields because of high specific surface area, good chemical and mechanical properties, high thermal stability, large pore volume, and uniform and controllable porous structure. These outstanding properties enable mesoporous structures to be excellent candidates for various practical applications, including as a catalyst and its support, adsorption and separation, energy conversion and storage, environmental remediation, drug delivery, and biomedical applications [12][13][14][15][16][17][18][19]. At first, mesopores in carbon structures were produced by enlarging micropores via oxidation during activation process, such as activated carbons, or at the interstices between carbon particles, such as carbon aerogels.…”

Dense T-Nb2O5/Carbon Microspheres for Ultrafast-(Dis)charge and High-Loading Lithium-Ion Batteries

“…In situ HRTEM investigations were performed during the lithiation reaction (Figure ). , Before lithiation, the Nb 2 O 5 phase along the [2̅10] zone axis can be found from the enlarged HRTEM images (Figure a,b) and FFT pattern (Figure c). The lattice fringes are indexed to be the (001) and (2̅4̅1) planes of Nb 2 O 5 with spacing distances of 3.9 and 2.3 Å, respectively.…”

A High‐Energy NASICON‐Type Na3.2MnTi0.8V0.2(PO4)3 Cathode Material with Reversible 3.2‐Electron Redox Reaction for Sodium‐Ion Batteries

“…Sodium-ion batteries (SIBs) are attractive candidates for grid-scale energy storage. [1][2][3][4] However, bottlenecks still exist in the energy density and cyclability of cathode materials. [5][6][7][8][9] Cathode materials largely determine the electrochemical performances of SIBs.…”