Title
Enhanced performance of MoO2–MoO3–C composite electrode with polyvinyl alcohol as carbon source for zinc-ion capacitors
Authors
[ 1 ] Instytut Chemii i Elektrochemii Technicznej, Wydział Technologii Chemicznej, Politechnika Poznańska | [ P ] employee
Scientific discipline (Law 2.0)
Year of publication
2026
Published in
Journal year: 2026 | Journal volume: vol. 141, Part C
Article type
scientific article
Publication language
english
Keywords
EN
- Zinc ion capacitors
- MoO2-MoO3-C composite
- Polyvinyl alcohol
- CV kinetics
- Ex situ characterization
- Ion insertion mechanism
Abstract
EN With the increasing demand for sustainable energy storage, zinc ion capacitors (ZICs) have attracted significant attention due to their high safety, low cost, and abundant resources. This study systematically evaluates MoO2–MoO3–C composite electrodes with varying polyvinyl alcohol (PVA) binder contents (optimized at a 125 wt% PVA/AMT ratio), optimizing electrodes and device performance in ZnI2 electrolyte. Structural characterization via X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analysis confirmed a mesoporous electrode architecture with uniform Mo–O–C interfaces, facilitating rapid ion transport. Cyclic voltammetry (CV) revealed that at 125 wt% PVA/AMT ratio, the electrode material exhibited a dominant capacitive contribution (53.1 % at 10 mV s−1), while higher PVA content (175–225 wt%) shifted the charge storage mechanism toward diffusion-controlled processes, as evidenced by b-value analysis. Galvanostatic charge–discharge (GCD) tests confirmed a maximum specific capacitance of 230.4 F g−1 at 0.12 A g−1 for the sample at a 125 wt% PVA/AMT ratio. Ex situ Raman spectroscopy demonstrated ion-insertion-induced structural evolution: Zn2+ and I− intercalation caused distinct G-band shifts (Δ +4.8 cm−1 for I−), reflecting lattice stress and defect activation, while ex situ X-ray photoelectron spectroscopy (XPS) revealed dynamic redox behavior of Mo species (Mo4+/Mo6+ ratio evolution) and surface chemistry modulation via ion-specific interactions. Electrochemical impedance spectroscopy (EIS) showed minimized charge transfer resistance (0.426 Ω) and internal resistance (0.614 Ω) at a 75 wt% PVA/AMT ratio, whereas the device at a 175 wt% PVA/AMT ratio delivered superior cycling stability (82.8 % capacitance retention after 10,000 cycles). This work provides mechanistic insights into PVA-driven electrode optimization and ion-storage dynamics, advancing the development of high-performance ZICs for large-scale energy storage systems.
Date of online publication
12.11.2025
Pages (from - to)
119414-1 - 119414-15
Comments
Article number: 119414
Ministry points / journal
100
System created by Poznań University of Technology
and Poznan Supercomputing and Networking Center
Log in through eKonto to add to SIS