A Low-Cost Substrate-Integrated Lead-Carbon Hybrid Ultracapacitor with an Organic Metal

A cost-effective substrate-integrated lead-carbon hybrid ultracapacitor using an organic metal is developed and performance tested. The hybrid ultracapacitor employs flexible exfoliated graphite sheets as negative plate current-collectors that are coated amperometrically with a thin layer of organic metal, namely poly-aniline; the latter providing good adhesivity to activated carbon layer that is pasted on to it for realizing an electrical-double-layer capacitor. The positive plate comprises the conventional lead sheet that is converted electrochemically into a substrate-integrated lead-oxide electrode.¹ 12V substrate-integrated lead-carbon hybrid ultracapacitor both in absorbent-glass-mat and polymeric silica gel electrolyte configurations are developed and performance tested. It is possible to realize 12V lead-carbon hybrid ultracapacitors both in absorbent-glass-mat and silica gel configurations with capacitance values of ~200 F and ~300 F, respectively, with faradaic efficiency value of ~ 90 % and cycle-life in excess of 100000 cycles. The effective cost of these ultracapacitors is estimated to be about US$ 4-5 Wh^-1 as compared to US$20-30 Wh^-1 for presently available commercial ultracapacitors. The performance-test data for 12V devices are summarized in Table 1. The galvanostatic discharge data and pulse cycle-life testing data for the substrate-integrated lead-carbon hybrid ultracapacitor are shown in Figures 1 and 2, respectively.²

Reference

1. A.  Banerjee, M. K. Ravikumar, A. Jalajakshi, P. S. Kumar, S. A. Gaffoor, and A. K. Shukla, J. Chem. Sci., 124, 747 (2012).
2. A. K. Shukla and A. Banerjee, Indian Patent Application No. 1454/CHE/2014, dated 19/03/2014.