Electrochemical and spectroscopic studies of carbon-based porous electrodes for lithium-sulfur batteries

A. TESIO; V. FLEXER; A. N. ARIAS; G. PLANES

Congreso; 20th Topical ISE Meeting; 2017

It has been reported that Li-S batteries, with Li metal as anode and S as cathode, would have a much higher specific energy compared to lithium-ion batteries available today. Furthermore, the great abundance and low cost of sulfur explain why these batteries are considered as promising energy storagesystems although they are still at a research and development stage.The energy gain when comparing Li-ion batteries with Li-S batteries is evident. This is because the discharge product at the cathode can store much more lithium and therefore more charge per unit mass with respect to discharge products in Li-ion batteries. In addition, the Li metal anode accumulates much more charge than intercalated graphite (C6Li).Although many significant progresses have been achieved in the field of Li-S batteries, its further development is still limited by several issues. Major challenges to attack are:? Li metal anodes are chemically and morphologically unstable because of the drastic changes in volume provoking the growth of dendrites;? Recharge with low efficiency and slow kinetics due to insulating nature of sulfur and other reaction products such as Li2S;? Capacity decays in successive cycles by formation of polysulfide intermediates which give rise to unwanted mechanisms known as shuttle mechanisms.In the current research project, we have planned the synthesis of new materials that will be tested as possible cathode materials. For our target materials the size and distribution of pores (micro, meso and nanopores) can be varied while keeping the same chemistry and the most of the other material properties.The materials will be characterized to have structures with porosities and surface chemistry well defined.In this work, a number of porous electrodes were synthesized by hard template method using melamine. We explore the use of melamine for several reasons; the first is the low solubility of melamine in the polymerization media, which makes possible its use as a hard template. Moreover, melamine has been reported as a Nitrogen precursor, able to modify the phenolic resin (resorcinol-formaldehyde) adding N containing groups. Last, but not least, the porous carbon is obtained in a single step from low-cost commercial precursors.Here we report the synthesis, impedance spectroscopy (EI) analysis and electrochemical/microscopic characterization of the base electrodes.