The article "Where Do Batteries End and Supercapacitors Begin?" by Patrice Simon, Yury Gogotsi, and Bruce Dunn discusses the distinction between batteries and supercapacitors. Batteries have high energy density but slow charging, while supercapacitors have high power density and fast charging but low energy density. Both rely on electrochemical processes, but different mechanisms determine their performance. Recent research aims to combine the high energy density of batteries with the high power and long cycle life of supercapacitors. However, the blurring of these two technologies can lead to confusion and misleading claims. Electrochemical measurements can distinguish between different types of energy storage materials. Supercapacitors store charge through adsorption of ions on electrode surfaces, while batteries rely on redox reactions. Pseudocapacitors, which involve redox reactions, can achieve battery-like energy density with supercapacitor-like power and cycle life. The article emphasizes the importance of clear terminology and proper evaluation of materials to avoid confusion. It also highlights the role of nanoscale materials in enhancing power density but notes that faradaic redox peaks and galvanostatic profiles remain battery-like. The article concludes that proper terminology and measurements are essential for progress in electrical energy storage.The article "Where Do Batteries End and Supercapacitors Begin?" by Patrice Simon, Yury Gogotsi, and Bruce Dunn discusses the distinction between batteries and supercapacitors. Batteries have high energy density but slow charging, while supercapacitors have high power density and fast charging but low energy density. Both rely on electrochemical processes, but different mechanisms determine their performance. Recent research aims to combine the high energy density of batteries with the high power and long cycle life of supercapacitors. However, the blurring of these two technologies can lead to confusion and misleading claims. Electrochemical measurements can distinguish between different types of energy storage materials. Supercapacitors store charge through adsorption of ions on electrode surfaces, while batteries rely on redox reactions. Pseudocapacitors, which involve redox reactions, can achieve battery-like energy density with supercapacitor-like power and cycle life. The article emphasizes the importance of clear terminology and proper evaluation of materials to avoid confusion. It also highlights the role of nanoscale materials in enhancing power density but notes that faradaic redox peaks and galvanostatic profiles remain battery-like. The article concludes that proper terminology and measurements are essential for progress in electrical energy storage.