Open Access Research Article Issue
Ionic liquid-mediated PEO-based solid-state electrolyte membrane modified with Dawson-type polyoxometalates
Polyoxometalates 2023, 2 (3): 9140036
Published: 28 September 2023

All-solid-state batteries are promising candidates for the future generation of energy storage materials. An ideal solid-state electrolyte should have the advantages of excellent compatibility with electrodes and decent ionic conductivity. Nevertheless, the inherent low ionic conductivity of polyethylene oxide (PEO)-based electrolytes leads to low capacity, which significantly limits their wide commercial application. In this study, Dawson-type Li6P2Mo18O62 (LPM) or Li6P2W18O62 (LPW) was selected as lithium salt, combined with ionic liquids (ILs) with ether oxygen chains, and incorporated into a polymer matrix blended with PEO and polyvinylidene fluoride as fillers. A polymer electrolyte film with a smooth surface and uniform filler distribution was prepared using a mechanical co-blending method. The challenge of polyoxometalates as ion-conducting materials is attributed to the strong binding ability of their anion clusters to cations. One prominent benefit of this study is that the dissociation of Li+ from LPM or LPW is facilitated by ILs and relies on the ether oxygen chains in ILs for transport, yielding composites with favorable conduction properties. This study demonstrates the vast potential of polyoxometalates in the field of ionic conductivity.

Open Access Research Article Issue
Zwitterion-dissociated polyoxometalate electrolytes for solid-state supercapacitors
Polyoxometalates 2023, 2 (1): 9140019
Published: 02 February 2023

Releasing cations from highly negatively charged polyoxometalates (POMs) is never an easy task. Herein, by using a zwitterion (1-sulfopropyl-3-methylimidazolium salt, MIMPS) to dissociate POMs, the proton conductivity of POM electrolytes was enhanced and the capacitive performance of solid-state supercapacitors (SCs) based on polyaniline was further improved. MIMPS can promote the dissolution and dissociation of POMs in polymer solutions, releasing more mobile protons, which is conducive to rapid proton transport. The MIMPS-modified SCs have higher capacitive performance, with an areal capacitance of 13 F·cm−2 at a current density of 0.5 mA·cm−2, compared to SCs without MIMPS (6.4 F·cm−2). In addition, the MIMPS-modified SCs have lower interfacial impedance, indicating that MIMPS can improve the proton conductivity and interfacial conduction. This work provides a new strategy for improving the overall performance of SCs by optimizing POM-based electrolytes with a zwitterion.

Research Article Issue
Oxygen vacancy engineering of calcium cobaltate: A nitrogen fixation electrocatalyst at ambient condition in neutral electrolyte
Nano Research 2021, 14 (2): 501-506
Published: 05 September 2020

In order to sustainably transform N2 to ammonia (NRR) using electrocatalysts under mild ambient condition, it is urgent to design and develop non-nobel metal nanocatalysts that are inexpensive and suitable for mass-production. Herein, a calcium metalate catalyst CaCoOx with oxygen vacancies was synthesized and used as an electrocatalyst for NRR for the first time, whose morphology can be controlled by the calcination temperature and the heating rate. Under the optimal conditions, the CaCoOx catalyst achieved the yield of nitrogen conversion to ammonia of 16.25 μg·h-1·mgcat.-1 at the potential of -0.3 V relative to the reversible hydrogen electrode (RHE) with a Faraday efficiency of 20.51%. The electrocatalyst showed good stability even after 12 times recyclability under environmental conditions and neutral electrolyte. Later, the electrocatalytic nitrogen reduction performance of CaFeOx, CaNiOx, CaCuOx was investigated. These earth-rich transition metals also exhibited certain NRR electrocatalytic capabilities, which provided a door for further development of inexpensive and easily available transition metal as nitrogen reduction electrocatalysts.

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