Solid-State Supercapacitors with Enhanced Performance Using Al<sup>3+</sup>-Doped Li<sup>+</sup> Ion Perovskite Electrolyte Integrated with Carbon Aerogel Electrode
Bhargab Sharma, Hardeep, Kamaldeep Bisht, Ashish Kumar Singh, Rashmi Singh, Anshuman Dalvi
Abstract
High Resolution Image Download MS PowerPoint Slide We report the performance of solid-state ceramic supercapacitors (SSCs) based on a novel composite electrolyte comprising aluminum-doped lithium lanthanum titanate perovskite, Li 0.36 La 0.56 Ti 0.995 Al 0.005 O 3 (Al 3+ -doped LLTO), and the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM BF 4 ). Rietveld refinement of X-ray diffraction data confirms the preservation of the tetragonal perovskite phase after Al 3+ substitution, indicating structural stability of the host lattice. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy further corroborate the successful incorporation of Al 3+ without forming secondary phases. The addition of ∼6 wt % EMIM BF 4 into Al-LLTO matrix significantly enhances the room-temperature ionic conductivity to ∼10 –3 Ω –1 cm –1, nearly 3 orders of magnitude greater than that of pristine LLTO, resulting into improved long-range electrical transport. Further, novel SSCs have been fabricated by sandwiching the composite electrolyte between high surface area freeze-dried carbon aerogel (FD-CA) coated copper electrodes and assembled using a low-cost hot-roll lamination approach. The devices at 35 °C exhibited a high specific capacitance of ∼370 F g –1 at 1 mA/2 V, excellent cycling stability with ∼87% capacitance retention over 15,000 cycles at 2 V and 2 mA (1 A g –1 ), and stable Coulombic efficiency of ∼99%. These symmetric SSCs demonstrate ideal electric double-layer capacitive behavior for operating potential ≤ 2 V. These results highlight the potential of Al 3 -doped LLTO/EMIM BF 4 composite electrolytes in combination with FD-CA-based electrodes for the development of safe, efficient, stable and scalable solid-state supercapacitors.