The article "To Be or Not To Be Pseudocapacitive?" by Thierry Brousse, Daniel Bélanger, and Jeffrey W. Long, published in the JES Focus Issue on Electrochemical Capacitors, discusses the distinction between true pseudocapacitive materials and those that are often mislabeled as such. The authors clarify that pseudocapacitance refers to materials with an electrochemical signature similar to capacitive electrodes, such as activated carbon, but where charge storage originates from electron-transfer mechanisms rather than simple ion accumulation in the double layer. They argue that materials like nickel oxide or hydroxide and cobalt oxide/hydroxide should not be described as pseudocapacitive because their charge storage mechanisms are more akin to battery materials, which involve faradaic reactions. The article provides a detailed explanation of the fundamental electrochemistry behind pseudocapacitance and emphasizes that the term "pseudocapacitance" should only be used for materials that exhibit a sharp electrochemical response typical of capacitive carbon electrodes. The authors also discuss the confusion surrounding the term, particularly in the context of two-terminals devices, where the behavior of the entire device does not necessarily reflect the individual properties of its components. The discussion includes examples of materials such as Ni(OH)2 and MnO2, highlighting that while Ni(OH)2 shows redox peaks typical of faradaic behavior, MnO2 exhibits a rectangular-shaped CV, which is characteristic of pseudocapacitance. The authors conclude that the term "pseudocapacitive" should be reserved for materials like MnO2 that display electrochemical behavior similar to capacitive carbon electrodes, and not for materials like Ni(OH)2 or cobalt oxides that show high-rate capability but with a faradaic signature. The article aims to provide clarity and guidance to researchers and practitioners in the field, ensuring that the correct terminology is used to describe the electrochemical behavior of different materials.The article "To Be or Not To Be Pseudocapacitive?" by Thierry Brousse, Daniel Bélanger, and Jeffrey W. Long, published in the JES Focus Issue on Electrochemical Capacitors, discusses the distinction between true pseudocapacitive materials and those that are often mislabeled as such. The authors clarify that pseudocapacitance refers to materials with an electrochemical signature similar to capacitive electrodes, such as activated carbon, but where charge storage originates from electron-transfer mechanisms rather than simple ion accumulation in the double layer. They argue that materials like nickel oxide or hydroxide and cobalt oxide/hydroxide should not be described as pseudocapacitive because their charge storage mechanisms are more akin to battery materials, which involve faradaic reactions. The article provides a detailed explanation of the fundamental electrochemistry behind pseudocapacitance and emphasizes that the term "pseudocapacitance" should only be used for materials that exhibit a sharp electrochemical response typical of capacitive carbon electrodes. The authors also discuss the confusion surrounding the term, particularly in the context of two-terminals devices, where the behavior of the entire device does not necessarily reflect the individual properties of its components. The discussion includes examples of materials such as Ni(OH)2 and MnO2, highlighting that while Ni(OH)2 shows redox peaks typical of faradaic behavior, MnO2 exhibits a rectangular-shaped CV, which is characteristic of pseudocapacitance. The authors conclude that the term "pseudocapacitive" should be reserved for materials like MnO2 that display electrochemical behavior similar to capacitive carbon electrodes, and not for materials like Ni(OH)2 or cobalt oxides that show high-rate capability but with a faradaic signature. The article aims to provide clarity and guidance to researchers and practitioners in the field, ensuring that the correct terminology is used to describe the electrochemical behavior of different materials.