Mishra Neeraj Kumar, Mondal Rakesh, Singh Preetam
Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University) Varanasi Uttar Pradesh 221005 India
RSC Adv. 2021 Oct 20;11(54):33926-33937. doi: 10.1039/d1ra05180f. eCollection 2021 Oct 18.
To overcome the environmental challenges caused by utilization of fossil fuel based energy technologies and to utilize the full potential of renewable energy sources such as solar, wind and tidal, high power and high energy density containing large scale electrochemical energy storage devices are a matter of concern and a need of the hour. Pseudocapacitors with accessibility to multiple oxidation states for redox charge transfer can achieve a higher degree of energy storage density compared to electric double layer capacitors (EDLC) and the hybrid supercapacitor is one of the prominent electrochemical capacitors that can resolve the low energy density issues associated with EDLCs. Due to its open pore framework structure with superior structural stability and accessibility of Co redox states, porous anhydrous CoCO nanorods are envisaged here as a potential energy storage electrode in a pseudo-capacitive mode. Superior specific capacitance equivalent to 2116 F g at 1 A g in the potential window of 0.3 V was observed for anhydrous CoCO nanorods in aqueous 2 M KOH electrolyte. A predominant pseudo-capacitive mechanism seems to be operative behind the high charge storage at electrodes as intercalative (Inner) and surface (outer) charge storage contributions were found to be 75% and 25% respectively. Further, in full cell asymmetric supercapacitor (ASC) mode in which porous anhydrous CoCO nanorods were used as positive electrodes and activated carbon (AC) was utilised as negative electrodes within an operating potential window of 1.3 V, a highest specific energy of W h kg and specific power of ∼647 W kg at 0.5 A g current density were obtained with superior cycling stability. High cycling stability coupled with superior electrochemical storage properties make anhydrous CoCO nanorods potential pseudo-capacitive electrodes for large scale energy storage applications.
为了克服基于化石燃料的能源技术利用所带来的环境挑战，并充分利用太阳能、风能和潮汐能等可再生能源的全部潜力，具有高功率和高能量密度的大规模电化学储能装置成为人们关注的焦点和当务之急。与双电层电容器（EDLC）相比，具有多种氧化态可用于氧化还原电荷转移的赝电容器能够实现更高程度的储能密度，而混合超级电容器是能够解决与EDLC相关的低能量密度问题的突出电化学电容器之一。由于其具有开放孔框架结构，具有优异的结构稳定性和钴氧化还原态的可及性，多孔无水CoCO纳米棒在此被设想为一种潜在的赝电容模式储能电极。在2M KOH水溶液电解质中，无水CoCO纳米棒在0.3V的电位窗口下，在1A g时观察到相当于2116F g的优异比电容。电极处的高电荷存储背后似乎主要是赝电容机制起作用，因为发现插层（内）和表面（外）电荷存储贡献分别为75%和25%。此外，在全电池不对称超级电容器（ASC）模式中，多孔无水CoCO纳米棒用作正极，活性炭（AC）用作负极，在1.3V的工作电位窗口内，在0.5A g电流密度下获得了最高比能量为W h kg和比功率约为647W kg，具有优异的循环稳定性。高循环稳定性加上优异的电化学存储性能，使无水CoCO纳米棒成为大规模储能应用的潜在赝电容电极。
