Structural modification of carbon electrode to improve the performance for next generation secondary battery

Abstract

A smart grid is a power grid that provides high-quality power services and maximizes energy use efficiency by intelligentizing and upgrading the power grid using battery and information and communication technologies. In addition, the smart grid can reduce energy waste by improving energy efficiency and prevent global warming by reducing the use of fossil fuels in the existing power generation facilities by reducing energy waste and activating distributed power based on new and renewable energy. The core of such a smart energy grid is to efficiently store and supply electric energy by dividing grid energy storage and mobile energy storage. Actually, the battery requirements for each grid energy storage and mobile energy storage are quite different. However, it is a reality that lithium-ion batteries that exhibit high technological maturity and economic feasibility have been applied uniformly in the electrochemical-based energy storage device technology, which is the core technology of the smart energy grid. Therefore, developing a secondary battery technology suitable for different demands such as future grid energy storage and mobile energy storage will be a more strategic and effective way to build a smart energy grid. In line with this point of view, each chapter is divided into large-capacity energy storage and small-capacity energy storage, and studies were conducted to bring the electrochemical performance and economic feasibility of different systems into a commercially available stage. Chapter 2 deals with highly defective carbon electrode to relieve the poor reversibility of zinc-bromine redox flow batteries (ZBBs). The key idea is to introduce a single vacancy carbon defect that causes strong orbital hybridization with Zn adatom to suppress the self-agglomeration of zinc adatom, which is associated with zinc dendrite growth. As a result, by applying a carbon electrode having a high defect density to ZBB, the reversibility of zinc dramatically increased, and a long-term cycling of more than 5,000 cycles was demonstrated. Chapter 3 developed a membraneless flowless Zn-Br battery (MLFL-ZBB) that lowers the high levelized cost of energy stored (LCOES) of ZBB and lithium ion batteries (LIBs). The main point is that a multifunctional electrode developed through a porous electrode doped with a large amount of nitrogen operates an aqueous battery that can be driven without the use of a separator and pumping system. As a result, the possibility of a new concept aqueous secondary battery technology capable of stably operation for about 1,000 cycles was proposed. Chapter 4 deals with the technology of anode-free lithium metal batteries (AF-LMBs) with high reversibility through a three-dimensional current collector with a high carbon defect density. Through a carbon defect structure that can suppress electrolyte decomposition reaction and lithium dendrite formation at the same time, we developed AF-LMBs that operates stably under high current density charging and discharging conditions while using lean electrolyte, room temperature, normal pressure, and high capacity cathode.