Current knowledge on supercapacitors, hybrid supercapacitors, and comparison with Lithium-Ion Cells – a review

The growing demand for efficient and durable energy storage technologies has accelerated the development and deployment of advanced electrochemical systems. This review presents a comparative analysis of three key energy storage technologies: electric double-layer capacitors (EDLC), lithium-ion hybrid capacitors (LIC), and conventional lithium-ion batteries. The study explores their internal structures, charge storage mechanisms (non-faradaic vs. faradaic), electrochemical characteristics, and performance parameters including energy density, power density, cycle life, and thermal stability. LIC, which combine a capacitive electrode with a battery-type electrode, are shown to bridge the performance gap between EDLC and lithium-ion batteries by offering significantly higher power density and cycle life than batteries, and greater energy density and lower self-discharge than EDLC. Commercial examples such as SECH and VinaTech LIC are discussed in terms of operational parameters and practical deployment. Quantitative comparisons indicate that LIC can reach energy densities up to 77 Wh/kg and withstand over 50,000 chargedischarge cycles, positioning them as promising candidates for high-frequency cycling, fast-charging, and hybrid grid-storage systems. The paper concludes that further advancements in electrode materials and solid-state electrolytes are essential to unlock the full potential of LIC in both mobile and stationary energy storage applications.