Tuning the interlayer of transition metal oxides for electrochemical energy storage

Abstract

Layered transition metal oxides are some of the most important materials for high energy and power density electrochemical energy storage, such as batteries and electrochemical capacitors. These oxides can efficiently store charge via intercalation of ions into the interlayer vacant sites of the bulk material. The interlayer can be tuned to modify the electrochemical environment of the intercalating species to allow improved interfacial charge transfer and/or solid-state diffusion. The ability to fine-tune the solid-state environment for energy storage is highly beneficial for the design of layered oxides for specific mechanisms, including multivalent ion intercalation. This review focuses on the benefits as well as the methods for interlayer modification of layered oxides, which include the presence of structural water, solvent cointercalation and exchange, cation exchange, polymers, and small molecules, exfoliation, and exfoliated heterostructures. These methods are an important design tool for further development of layered oxides for electrochemical energy storage applications.

Improving the Performance of Layered Oxide Cathode Materials with Football‐Like Hierarchical Structure for Na‐Ion Batteries by Incorporating Mg2+ into Vacancies in Na‐Ion Layers

“…The direct use of the intrinsic vacancies in materials such as layered Na x TMO 2 ( x <1) could be a new insight. The layered nature of Na x TMO 2 determines the presence of open 2 D spaces that can accommodate Li/Na ions or molecules . However, a crucial feature of P2‐Na x TMO 2 ( x <1) materials is that it is sodium deficient, which means the presence of abundant vacancies in such materials.…”

“…The layered nature of Na x TMO 2 determines the presence of open 2D spaces that can accommodate Li/Na ions or molecules. [1,12] However, ac rucial feature of P2-Na x TMO 2 (x < 1) materials is that it is sodium deficient, [13] which meanst he presence of abundantv acancies in such materials. These vacancies can be incorporated by homogeneous ions or heterogeneous ions at the same time to tune the microstructure of material, which causest he remarkable property differences of these materials.…”

C@TiO2/MoO3 Composite Nanofibers with 1T‐Phase MoS2 Nanograin Dopant and Stabilized Interfaces as Anodes for Li‐ and Na‐Ion Batteries

“…[11][12][13] Even thoughT iO 2 hasg reat advantages in structuralr eliability and cycling stability,t he low theoretical specific capacity limits its application. [16][17][18] Moreover,o wing to its open 2D ion-transportc hannels, MoS 2 can accommodate variousg uest ions (Li + /Na + /Mg 2 + )a nd provides more active sites for ion storage. [16][17][18] Moreover,o wing to its open 2D ion-transportc hannels, MoS 2 can accommodate variousg uest ions (Li + /Na + /Mg 2 + )a nd provides more active sites for ion storage.…”

Vanadium Pentoxide with H2O, K+, and Na+ Spacer between Layered Nanostructures for High‐Performance Symmetric Electrochemical Capacitors

“…[72] The diffusion control process of the electrode was fitted with a Warburg element Z w and determined the diffusion resistance (W R ) of the AVO, KVO, and NVO devices are 22.2, 25.6, and 24.2 Ω cm −2 . [75] Comparing 1D and 2D morphological structures, the 2D materials have more electroactive sites and the probability of electrolytic ions' interaction with the electroactive material is more [76] than the 1D nanostructure. Figure S10b (Supporting Information) presented the Nyquist plots of heattreated HAVO, HKVO and HNVO samples and the resultant plots were well fitted with the same equivalent circuit.…”

“…In addition, the removal of water molecules from the structure can create more defeat on the nanostructure and it effectively affects the pseudocapacitive behavior. [75] Comparing 1D and 2D morphological structures, the 2D materials have more electroactive sites and the probability of electrolytic ions' interaction with the electroactive material is more [76] than the 1D nanostructure. [77] Thus, the increase in resistance values of the heat-treated samples reveals that the conductivity of materials substantially dropped after loss of water molecules.…”