Ether–Water Hybrid Electrolyte Contributing to Excellent Mg Ion Storage in Layered Sodium Vanadate

Abstract

Magnesium ion batteries have potential for largescale energy storage. However, the high charge density of Mg 2+ ions establishes a strong intercalation energy barrier in host materials, causing sluggish diffusion kinetics and structural degradation. Here, we report that the kinetic and dissolution issues connected to cathode materials can be resolved simultaneously using a tetraethylene glycol dimethyl ether (TEGDME)−water hybrid electrolyte. The lubricating and shielding effect of water solvent could boost the swift transport of Mg 2+ , contributing to a high diffusion coefficient within the sodium vanadate (NaV 8 O 20 •nH 2 O) cathode. Meanwhile, the organic TEGDME component can coordinate with water to diminish its activity, thus providing the hybrid electrolyte with a broad electrochemical window of 3.9 V. More importantly, the TEGDME preferentially amassed at the interface, leading to a robust cathode electrolyte interface layer that suppresses the dissolution of vanadium species. Consequently, the NaV 8 O 20 • nH 2 O cathode achieved a specific capacity of 351 mAh g −1 at 0.3 A g −1 and a long cycle life of 1000 cycles in this hybrid electrolyte. A mechanism study revealed the reversible interaction of Mg 2+ during cycles. This organic water hybrid electrolyte is effective for overcoming the difficulty of multivalent ion storage.

Advances in studying interfacial reactions in rechargeable batteries by photoelectron spectroscopy

“…Even though these issues are still major obstacles there has been progress made and XPS is an invaluable tool for characterising and developing these systems. [152][153][154] In magnesium-ion batteries, the blocking nature of the SEI formed on Mg metal anodes can be overcome by several strategies. One compelling example is by Matsui et al 155 that uses intermetallic compounds such as Mg 3 Bi 2 to facilitate the deposition of Mg 2+ .…”

“…Even though these issues are still major obstacles there has been progress made and XPS is an invaluable tool for characterising and developing these systems. 152–154…”

Aqueous Nickel-Ion Batteries with Long Lifetime, High Capacity, and High Rate Capability Based on K2V6O16·1.64H2O Cathodes

“…As presented in Figure c, the existence of Ni 2p characteristic peaks at the fully discharged state originated from the insertion of Ni 2+ ions into the KVO electrode during the discharge process, corresponding to the reduction reaction of V 3+ /V 5+ . , Contrastively, the intensity of Ni 2p peaks (the spectra are normalized based on the K 2p peak) was significantly decreased at the fully charged state compared to that at the fully discharged state, corresponding to the release of Ni 2+ ions from the KVO cathode. The residual Ni 2p at the fully charged state may ascribe to the residual electrolyte on the surface of the KVO electrode, or the trapped Ni 2+ ions served as pillars to support the layered structure in the electrode. , The uptake/release of Ni 2+ ions was accompanied by the valence change of vanadium in KVO, as shown in Figure d. Typical peaks of the V 2p spectrum centered at 524.5 eV (2p 1/2 ) and 517.2 eV (2p 3/2 ) were detected at the pristine state, consistent with the values of V 5+ .…”

A high-performance hybrid supercapacitor by encapsulating binder-less FeCoSe2 nanosheets@NiCoSe2 nanoflowers in a graphene network

“…77,78 Generally, as the value of b approaches 0.50, the diffusion type of storage governs the electrochemical reaction, while the b value close to 1.0 indicates a contribution from the capacitive storage process. 79–82 Fig. 5(F) reflects the graph of log( i ) vs. log( v ), i.e.…”

“…This journal is © The Royal Society of Chemistry 2022 Sustainable Energy Fuels, 2022, 6, 3626-3642 | 3635 process. [79][80][81][82] Fig. 5(F) reects the graph of log(i) vs. log(v), i.e., the peak current density vs. sweep speed, and the obtained b values of the oxidation (anodic) and reduction (cathodic) peaks are 0.6387 and 0.6412, respectively.…”