Cellulose-based air-cathode loaded by in-situ hydrothermally synthesized NiFe2O4 for Al-air battery: Influence of surface chemistry on the electrochemical performance

Abstract

The influence of the cellulosic fabrics (CF) surface chemistry on hosting nickel ferrite (NF) and its application in Al-air battery was studied. CFs were modified with acrylate monomer bearing positively (COOCH2CH2N+(CH3)3Cl−) or negatively (-COO(CH2)3SO3K) charged functional groups at different degrees of graft-polymerization. NF was in-situ hydrothermally synthesized into the un/grafted-CF followed by in-situ polymerization of polyaniline (PANi) to enhance the electric conductivity nine orders of magnitude. This via altering the electron transport mechanism from the tunnelling to the variable-range hopping mechanism for CF-NF and PANied-CF-NF, respectively. XRD confirmed a single phase of Trevorite (NiFe2O4). SEM images showed a dense deposition of NF on the anionic fabrics and TEM images demonstrated the change of NF shape (nanorice – nanoctahedrons) and size (9–75 nm) as a function of the surface chemistry. Anionic ACs showed higher Ni+2 and Fe+3 uptake compared to the cationic ones as confirmed by ICP-OES and XPS. Cyclic voltammetry showed that NF reduced oxygen to water through 2 × 2 electron pathway. Electrochemical performance of ACs showed a good correlation with the NF content to an extent. Highest current density (4 mA/cm2) and discharge time (13.8 h) were obtained from anionic AC compared to 1.7–2.5 h for blank and cationized ACs, respectively.The authors thank SRDA grant agency for support through project APVV-23-0534 and APVV-22-0062 . Grant Agency VEGA through project VEGA 2/0137/23 and VEGA 2/0038/22 . This work was performed during the implementation of the project Building-up Centre for advanced materials application of the Slovak Academy of Sciences, ITMS project code 313021T081 supported by the Integrated Infrastructure Operational Program funded by the ERDF . The authors M.M and J.O. gratefully acknowledge the Ministry of Education, Youth and Sports of the Czech Republic - DKRVO ( RP/CPS/2024-28/003 ). Also, acknowledge Czech Science Foundation project no. 23-07244S for financial support. This study was carried out in the framework of the project FunGlass that has received funding from the European Union 's 2020 research and innovation program under grant agreement No. 739566 . Author \u0160.N. would like to acknowledge the Recovery and Resilience Plan for Slovakia under project No. 09I03-03-V04-00715