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.

Lithiated Manganese-Based Materials for Lithium-Ion Capacitor: A Review

“…The specific energy density of pseudocapacitors with an asymmetric configuration of two metal oxides is 5-10 W h kg 1 . The behavior of the lithiated manganese-based electrodes (LMP, LMO, and LMSO) reviewed in this paper resembles that of PCs [33][34][35][36]. Since the energy density is a product of capacitance and voltage, increasing the voltage is necessary to enhance the energy density.…”

“…Due to their many enticing qualities, including their high theoretical capacity (330 mA h g −1 ) when more than one lithium ion is extracted per formula unit, they are becoming increasingly popular [72][73][74]. The extraction of more than one lithium ion per formula unit provides high thermal stability [35]; Li 2 MnSiO 4 is a more promising orthosilicate electrode material because it allows for the reversible extraction of two moles of Li + ions utilizing the Mn 2+ /Mn 3+ and Mn 3+ /Mn 4+ redox couples, and this results in a greater energy density [74,75]. Li 2 MnSiO 4 has an orthogonal structure.…”

A Critical Review on Electrochemical Properties and Significance of Orthosilicate‐Based Cathode Materials for Rechargeable Li/Na/Mg Batteries and Hybrid Supercapacitors

“…The mesoporous morphology with orthorhombic Li 2 MnSiO 4 proposed as electrode material for HSC and it was exhibited a specific capacitance of about 175 F g −1 [240] . The Al 2 O 3 coated Li 2 MnSiO 4 nanocomposite was employed as an electrode material for HSC which showed the specific capacitance of 141.5 F g −1 and high‐power density of 4020.8 W kg −1 [241] . Recently, a multi‐walled carbon nanotube (MWCNT) embedded mesoporous Li 2 MnSiO 4 nanocomposite was synthesised and used as an electrode material for a hybrid supercapacitor in the aqueous electrolyte solution (2 M KOH) [242] .…”

“…[240] The Al 2 O 3 coated Li 2 MnSiO 4 nanocomposite was employed as an electrode material for HSC which showed the specific capacitance of 141.5 F g À 1 and high-power density of 4020.8 W kg À 1 . [241] Recently, a multi-walled carbon nanotube (MWCNT) embedded mesoporous Li 2 MnSiO 4 nanocomposite was synthesised and used as an electrode material for a hybrid supercapacitor in the aqueous electrolyte solution (2 M KOH). [242] The symmetric supercapacitors were assembled using 2 % MWCNT incorporated Li 2 MnSiO 4 (LMS2 C) as positive and negative electrodes which delivered the energy and power density of 7 Whkg À 1 and 150 Wkg À 1 .…”

Graphene‐functionalised Olivine Lithium Manganese Phosphate Derivatives for High Performance Lithium‐ion Capacitors

“…However, the limited power density and poor cycle life of LIBs as well as the lower energy density of SCs restrict their performance as independent energy storage devices in high rate applications [6,7]. Lithium ion capacitors (LICs) are considered as very promising hybrid energy storage devices with superior energy and power capabilities due to the synergies from combining battery and SCs features [8,9]. Generally, charge storage in LICs involves the combination of capacitive mechanism of supercapacitivetype electrodes and Faradaic processes occurring at the battery-type electrodes [10,11], yielding excellent energy and power densities.…”