Tailoring Li2SO4‒MgO‒P2O5 glasses for electrodes and electrolytes in solid ‒ state batteries with CoO doping by means of dielectric studies

Raja Sekhar Nallamothu; Marek Kostrzewa; Ayyagari Venkata Sekhar; Adam Ingram; Tikkisetti Venkata Naga Keerti Kut; Pathuri Naresh; Gnanamuthu Sahaya Baskaran; Vandana Ravi Kumar; Nalluri Veeraiah

doi:10.1051/epjap/2025011

2024 Impact factor 0.9

Applied Physics

Eur. Phys. J. Appl. Phys. 100, 13 (2025)
https://doi.org/10.1051/epjap/2025011

Original Article

Tailoring Li₂SO₄‒MgO‒P₂O₅ glasses for electrodes and electrolytes in solid ‒ state batteries with CoO doping by means of dielectric studies

Raja Sekhar Nallamothu¹, Marek Kostrzewa²^*, Ayyagari Venkata Sekhar¹^,3, Adam Ingram², Tikkisetti Venkata Naga Keerti Kut⁴, Pathuri Naresh⁵, Gnanamuthu Sahaya Baskaran⁶, Vandana Ravi Kumar¹^** and Nalluri Veeraiah¹^,6^***

¹ Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar‒ 522 510, India
² Faculty of Physics, Opole University of Technology, Opole, Poland
³ Department of Nanotechnology, Acharya Nagarjuna University, Nagarjuna Nagar‒ 522 510, India
⁴ Department of Physics, Rajiv Gandhi University of Knowledge Technologies, IIIT Nuzvid, India
⁵ Department of Physics, Potti Sriramulu Chalavadi Mallikarjuna Rao College of Engineering & Technology (Autonomous), Vijayawada 520001, A.P., India
⁶ Department of Physics, Andhra Loyola College (Autonomous), Vijayawada 520008, A.P., India

^* e-mail: m.kostrzewa@po.opole.pl
^** e-mail: vrksurya@rediffmail.com
^*** e-mail: profnvr@gmail.com

Received: 13 June 2024
Accepted: 21 March 2025
Published online: 13 May 2025

Abstract

Li₂SO₄‒MgO‒P₂O₅ glasses with varying cobalt oxide (CoO) concentrations (0.2 to 1.0 mol%) were synthesised. Optical absorption studies revealed that cobalt ions predominantly exist in Co²⁺ state and occupied tetrahedral (T_d) sites when the concentration of CoO is at lower levels and largely octahedral (O_h) when its concentration is >0.6 mol%. Dielectric parameters and a.c. conductivity measured over broad ranges of frequency and temperature initially decreased with increasing CoO content up to 0.6 mol% and for further increase of CoO these parameters were found to increase. This behaviour is linked to the dual role of Co²⁺. At lower concentrations, it strengthens the glass network, while at higher levels it weakened the network and enhanced charge carrier transport, leading to higher conductivity. Observed dipolar relaxation is attributed to Co²⁺(O_h)–oxygen ion complexes. Conductivity studies indicated, ionic conduction dominates at lower CoO levels, while polaronic conduction, due to electron transfer between Co²⁺ and Co³⁺ states, prevails at higher concentrations. From these findings it is concluded that, glasses with lower CoO concentrations (<0.6 mol%) exhibited larger ionic conductivity, making them ideal for electrolyte applications. Conversely, those with higher CoO content show enhanced electronic conductivity, making them more appropriate for use as electrodes in solid‒state batteries.