Advanced Zn anode host for aqueous Zinc-ion battery

• Main Author: Phui, Eugene Kai Yuan
• Other Authors: Fan Hongjin
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Science::Chemistry::Physical chemistry::Electrochemistry; Science::Physics::Electricity and magnetism
• Online Access: https://hdl.handle.net/10356/156736
• Institution: Nanyang Technological University

Aqueous Zinc-ion batteries (AZIBs) have been widely regarded as one of the up-and-coming source of energy and the increased demand for high-quality, low-cost rechargeable energy storage device has accelerated its development. Zinc (Zn) is one of the most abundant, naturally occurring element, with high electrical conductivity, chemical stability in water, nontoxicity, superb ductility, and is easy to machine. All the aforementioned qualities support the concept of implanting a Zn anode in aqueous electrolytes to enhance the performance of the battery (working potential and capacity). However, past research has brought up several concerns. The formation of Zn dendrites, passivation of unwanted side reactions and by-products on Zn metal anodes diminish their usefulness. These may cause short-circuit and irreversible capacity loss, which will decrease the battery’s life. In this project, we introduce a Sn-modified 3D Carbon Nanofibers (Sn-CNF) as a permeable Zn host, as the anode of AZIBs. A simple hard-template method will be used to make hollow carbon spheres with zincophilic Sn nanoparticles, which will then be calcined. Porous conductive carbon shells paired with plentiful Sn nanoparticles may effectively regulate Zn2+ flux in the electrolyte, guiding uniform Zn deposition and suppressing Zn dendrite growth. Sn with low Hydrogen Evolution Reaction (HER) activity can also prevent hydrogen from leaking onto the Zn surface. This multifunctional Zn host for the AZIB anode is intended to improve cycling stability and reduce electrode polarisation. CNF is used to create a interconnected conductive 3D porous scaffold, with the ability to perform cell therapy and high-throughput screening, that reduces local current density, evens out the electric field and confines dendrites in a physical manner. In symmetric cells, Zn-deposited Sn-CNF (Sn-CNF@Zn) exhibited steady voltage polarisation over 180 hours at current density of 5 mA cm-2, with a capacity of 1 mAh cm-2. In addition, Sn-CNF@Zn||NaVO full cells also displayed a low decay rate (0.03 % per cycle) and excellent cycling stability at 10 A g-1 over 1000 cycles. These findings pave the way for AZIBs with high energy density and a long lifespan.