Session 2C — Symposium: “Electrochemical Energy Storage and Sustainability”

Organizers: S Sampath (IISc, Bengaluru) and K Vijayamohanan Pillai (IISER, Tirupati)

Supercapacitor (-battery) to supercabattery: An innovative energy storage system View Presentation

Progressive depletion of non-renewable fossil fuels has resulted in distressing effects of greenhouse gas emission causing global warming and energy security. These facts have reformed the perception of world community on sustainable and environment friendly energy storage system. To envisage features viz., fast discharge and charge capability, enhanced recharge durability with high energy density into the energy storage system are essential to achieve transformation and viability. Although the competing battery technology is significantly advanced, the systems do not entirely meet the energy demands of applications especially for rapid power profiles and the challenges due to safety, size, cost, and overall management issues. To meet the concurrent objective of achieving high-energy and high-power demands, hybridization concepts combining Batteries (energy) and Supercapacitors (power) become promising as power sources improved life and cost effectiveness. Traditionally, hybrid power systems invoke external paralleling of Battery and Supercapacitor banks as individual strings. But the architecture lacks simple management for practical application due to different charge and discharge characteristics of Lithium ion cells (4V, Faradaic) and Supercapacitors (2.5V, Non Faradaic). Also, the issues related to inherent lower voltage and self-discharge in Supercapacitors call for a stringent cell balancing in the present external hybridization concepts. To overcome these present technical issues, Supercabattery (Supercapacitor + Battery) is a recent innovation in the area of electrochemical energy storage system that efficiently facilitates high rate discharge while retaining the higher energy density. The novel internal hybridization configuration exhibits improved performance attributes of high power rate and energy with cell operating voltage of batteries (> 4.0 V, as the chosen Lithium systems). VSSC/ISRO has designed, developed and qualified Supercabattery devices (0.5 Ah to 3.0 Ah capacity values) with minimal self-discharge and improved cell performance characteristics demonstrated for space applications. Features of higher cell voltage, higher power and energy density and ability to fast discharge will possibly make it as a promising energy storage device suitable for powering electric vehicles with significant performance advantages sorting out the present issues associated with the conventional hybrid systems of Battery and Supercapacitor connected externally.