One produced three: A capacitor-battery integration strategy in a dual-carbon device

Abstract Electrochemical energy storage (EES) devices having both high power density and high energy density are highly desirable. Although metal-ion hybrid capacitors (MIHCs) integrating a battery-type anode and a capacitor-type cathode are wished to realize this target, state-of-the-art MIHCs just showed the compromise performance between high-power supercapacitors (SCs) and high-energy metal-ion batteries. Herein, we propose a new concept of “device-level integration” to realize the integration of SC, MIHC and dual-ion battery (DIB) in one device. By coupling a mixed and pre-potassiated activated carbon (AC)/graphite anode and another mixed AC/graphite cathode in a K+-based organic electrolyte, as-built device can exhibit three distinctly different energy storage behaviors including SC, MIHC and DIB by simply tuning the applied voltage window. Consequently, this device is able to achieve the maximum power density at 0-2.8 V and the maximum energy density at 0-5.0 V, and exhibits a good combination of high power density and high energy density at 0-4.0 V. This work may open a new avenue for building advanced EES devices with adjustable power and energy output characteristics.