Orthorhombic Nanostructured Li₂MnSiO₄/Al₂O₃ Supercapattery Electrode with Efficient Lithium‐Ion Migratory Pathway

Abstract A Li₂MnSiO₄/Al₂O₃ nanocomposite (LMSA) was prepared as positive electrode material for aqueous supercapatteries by hydrothermal synthesis of Li₂MnSiO₄ nanoparticles (LMS) followed by wet chemical coating with Al₂O₃. Scanning electron microscopy (SEM) mapping of the spherical LMSA nanoparticles indicated a homogenous distribution of the constituent atoms. Small‐angle X‐ray scattering (SAXS) measurements revealed that a prominent population of the nanoparticles show a center‐to‐center spacing of 7 nm. This is resulting in a large surface area accessible for the migration of Li‐ions and efficient charge storage, leading to improved electrochemical performance as a supercapattery electrode. X‐ray diffraction (XRD) and solid‐state nuclear magnetic resonance spectroscopy (SS NMR) studies portrayed the orthorhombic (Pmn2₁) crystalline phase of the LMSA and LMS materials which provides a good migratory pathway for the Li‐ions. The nanocomposite showed a high rate performance as a positive electrode in an aqueous supercapattery assembled with activated carbon as the negative electrode. The hybrid cell delivered a maximum specific capacitance of 141.5 F g⁻¹ and a maximum specific power of 4020.8 W kg⁻¹ with good cyclic stability and capacitance retention of 93.6 % after 100 cycles. These results the promising potential of the Li₂MnSiO₄/Al₂O₃ nanocomposite as candidate for advanced supercapatteries.