High‐Energy Efficiency Membraneless Flowless Zn–Br Battery: Utilizing the Electrochemical–Chemical Growth of Polybromides

• Published in: Advanced materials (Weinheim) 2019-12, Vol.31 (52), p.e1904524-n/a
• Main Authors: Lee, Ju‐Hyuk, Byun, Yearin, Jeong, Gyoung Hwa, Choi, Chanyong, Kwen, Jiyun, Kim, Riyul, Kim, In Ho, Kim, Sang Ouk, Kim, Hee‐Tak
• Format: Article
• Language: English
• Subjects: Anions; aqueous zinc‐based batteries; Bromine; Cost effectiveness; Crossovers; Discharge; electrochemical–chemical growth; Electrodes; Energy conversion efficiency; Energy efficiency; Energy storage; Life cycle costs; Materials science; membraneless batteries; multifunctional electrodes; N‐doped microporous electrodes; Organic chemistry; Power efficiency; Storage batteries; Storage systems; System effectiveness
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201904524

Aqueous Zn–Br batteries (ZBBs) offer promising next‐generation high‐density energy storage for energy storage systems, along with distinctive cost effectiveness particularly in membraneless and flowless (MLFL) form. Unfortunately, they generally suffer from uncontrolled diffusion of corrosive bromine components, which cause serious self‐discharge and capacity fade. An MLFL‐ZBB is presented that fundamentally tackles the problem of bromine crossover by converting bromine to the polybromide anion using protonated pyridinic nitrogen doped microporous carbon decorated on graphite felt (NGF). The NGF electrodes efficiently capture bromine and polybromide anions at the abundant protonated nitrogen dopant sites within micropores and facilitate effective conversion of bromine into polybromides through electrochemical–chemical growth mechanism. The MLFL‐ZBBs with NGF exhibit an extraordinary stability over 1000 charge/discharge cycles, with an energy efficiency over 80%, the highest value ever reported among membraneless Zn–Br batteries. Judicious engineering of an atomistically designed nanostructured electrode offers a novel design platform for low cost, high voltage, long‐life cycle aqueous hybrid Zn–Br batteries. A novel aqueous membraneless zinc–bromine battery using electrochemical–chemical growth of polybromide inside the electrode is presented. The new chemistry of this battery is enabled by precise engineering of a protonated N‐doped microporous electrode for polybromide anion adsorption and conversion; this is the first report of the use of anion adsorption by heteroatom doping.