Supercapacitors and batteries have been intensively investigated but there is much confusion and misleading between them in publications. In particular, some battery behaviours are incorrectly as supercapacitors and some reported “remarkable” performances like the high specific capacitance of 2188 F g⁻¹ for Ni(OH)₂ nanospheres are not true. It is likely that the energy storage mechanism and the similar device configuration/characterization techniques cause confusions. It is important to clarify and remove confusion about both theoretical and experimental aspects of these two types of energy devices. This review starts with briefing fundamentals of battery and supercapacitor specifically emphasizing the essential difference on energy storage mechanism between pseudocapacitors and batteries, in which the former undergoes rapid surface-controlled electrochemical reactions without diffusion control and phase transformation, while the latter stores energy in the crystal lattices or porous materials through much slower electrochemical reactions with limits from the phase transformation, chemical binding changes or/and reactant diffusions. Correct characterization and analysis methods such as cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy with a suggested working flowchart to distinguish them are presented while offering thoughtful discussions and explanations about the confusions. Perspectives are also offered for realizing high-energy density ECs without trading off its high power density.

超级电容器和电池已被广泛研究，但是出版物之间存在很多混淆和误导。特别是，某些电池行为不正确地用作超级电容器，而某些则报告了“显着”性能，如Ni（OH）₂的2188 F g ^-1的高比电容纳米球是不正确的。能量存储机制和类似的设备配置/特征化技术可能会引起混乱。重要的是要弄清和消除对这两种类型的能量装置的理论和实验方面的混淆。这篇综述首先从电池和超级电容器的基本原理入手，特别强调了伪电容器和电池之间在能量存储机制上的本质区别，其中前者经历了快速的表面控制电化学反应，而没有扩散控制和相变，而后者则将能量存储在晶体中晶格或多孔材料通过缓慢得多的电化学反应而受到相变，化学键变化或/和反应物扩散的限制。提出了正确的表征和分析方法，例如循环伏安法，恒电流充放电和电化学阻抗谱，并提出了建议的工作流程图来区分它们，同时提供了有关混淆的深思熟虑的讨论和解释。还提供了实现高能量密度EC的折衷方案，而无需权衡其高功率密度。