Engineering of Battery Type Electrodes for High Performance Lithium Ion Hybrid Supercapacitors

The researchers across the globe are working on improvement in energy density of supercapacitor without compromising its inherent supercapacitive properties.[1-4] The upgraded hybrid supercapacitor is derived from a battery type anode, a capacitive type cathode and organic electrolyte. However, the performance of hybrid supercapacitor is limited by the imbalance kinetics between the anode and cathode due to sluggish Faradic reaction of anode materials and less charge storage capacity of cathode materials. The design and development of lithium ion hybrid supercapacitor (LIC) can be possible by engineering anode, cathode and electrolyte materials. In this review, we focus on the evolution of anode materials for LICs fabrication. Different strategies to balance the kinetics between the cathode and the anode have already been reported, such as the engineering of novel materials and fabrication of different nanoarchitectures. LICs have been fabricated by tailoring different nanoarchitectures such as particles (0D), nanorods/nanowires/nanotubes (1D), thin sheets (2D) and hierarchical architectures (3D). The fabrication of nanostructured active materials with desired morphology (0D, 1D, 2D and 3D) and sizes with high aspect ratios facilitate fast lithium-ion insertion and extraction. The anode materials are divided into three types (i) lithium insertion reaction mechanism (ii) conversion reaction mechanism (iii) and the alloying reaction mechanism. The lithium insertion reaction-based materials have high stability whereas less capacity and energy density. In contrast to this, the conversion type electrodes have high energy density but low stability. Alloying type materials have ultra-high energy density while very low stability and reversibility. Hence, for getting high performance LIC all above mentioned aspects are required to be considered.