Stacking Ni–Al and Co–Al Layered Double Hydroxide for High-Energy and High-Power Composite Electrodes

Abstract

The requirement for high-power performance of secondary batteries suffering from inherent sluggish charge transfer kinetics is urgent for the expanding energy storage and conversion applications such as electric vehicles. A successful combination of high-power supercapacitors with high-energy secondary batteries in one energy storage device will meet the needs of both high power and energy density. We study the electrochemical behaviors of alternately stacked super-capacitive [Co4Al(OH)10]NO3 and [Ni4Al(OH)10]NO3 layered double hydroxide (LDH) electrodes. By cyclic voltammetry studies, the sandwich of [Co4Al(OH)10]NO3 lDH between [Ni4Al(OH)10]NO3 LDH and the Pt current collector results in the current amplification of the oxidation or reduction peaks to 4∼35 times. By galvanostatic charging/discharging, the 3-stacked Ni–Al|Co–Al|Ni–Al LDH electrode behaves better than the Co–Al|Ni–Al|Co–Al LDH electrode, exhibiting a maximal capacity, 338.1 mAh·g−1 under a current density of 1000 mA·g−1 and maintaining 288.6 mAh·g−1 within 400 cycles. It also has a much lower liquid-solid interface capacitor resistance and lower self-discharge. These results suggest that stacking in a suitable sequence contributes to high electrode performances, providing a strategy for producing energy storage and conversion devices. A synergetic charge transfer for the combination of Ni–Al and Co–Al LDH suggests that Co–Al LDH outstands as a bridge, accelerating the transfer of electrons.