Non-delaminated 2D MXene stacks modified Li surface: a reliable, scalable thin inter-layer-calated Li metal anode with improved cyclability and dendrite suppression

University Of Wisconsin-Milwaukee, Milwaukee WI

Investigators

Abstract

Energy storage at an affordable cost has emerged as one of the challenging issues for the energy sector, being critical for a wide range of applications ranging from electric vehicles to grid storage of renewable energies. The rapidly growing demand in high energy-density batteries for electrical vehicles requires scientists to explore new electrode materials that can deliver higher energy capacity. To this end, Li metal is attracting extensive attention in next-generation lithium-ion batteries. However, unstable and irreversible Li plating/stripping can result in a short battery lifetime and a serious safety issue related to the possible dendrite growth of lithium. This fundamental research project seeks to develop a hybrid electrode that is composed of novel 2-dimensional carbide or nitride nanomaterials called MXenes as a substrate to construct composite lithium metal anodes. The coated 2D MXene layers provide large volume of empty space between layers, better conductivity, and suppression of the dendrite growth. This approach of material design is also amenable to large-scale manufacturing methods for making battery anodes. If successful, the developed Li-metal electrode can be applied in various liquid-electrolyte and solid-state batteries. The experimental design, problem solving, and performance analysis of this project will be integrated with educational outreach for undergraduate students in the science, technology, engineering and math (STEM) fields particularly in energy storage field of materials science and engineering via a series of ‘Interest-Inspiring’ research experiences and courses. Two-dimensional nanomaterials such as MXenes display intense promise for lithium batteries due to the efficient and fast ion transport between layers and large surface areas available for improved ion adsorption and faster surface redox reactions. The open ion transport channels in MXenes shorten ion diffusion pathways and enable fast ion transport. In addition, they can act as functional substrates for incorporating various active materials for lithium ion batteries, improving the total capacity of the electrodes and enhancing the overall performance. The technical goal of this research project is to design a scalable 2D MXenes such as Ti3C2Tx stacks inter-layer-calated thin Li metal hybrid anode, which shows a highly reversible plating/stripping with a low overpotential upon long cycles in lithium ion batteries. The large surface area of the multi-layer MXene stacks with high mechanical flexibility ensures a high-capacity and reliable Li nucleation/growth upon plating and stripping. The highly reversible Li through the confined 2D configuration reduces the dead Li and electrolyte consumption by forming a thin solid electrolyte interphase (SEI) layer. The mossy/dendritic Li on the controllable inter-spaces between MXene layers is suppressed due to the lateral nucleation/growth on the 2D layered configuration, which is studied using in-situ observations and modeling. The fast charge-transfer due to the high electron conductivity and large inter-layer spacing leads to small contact/transfer resistances and rapid lithium ion diffusion on the MXene surface with terminations, enabling a drastically lowered energy barrier for Li nucleation/growth through inter-layer-calation as well as less SEI formation. If successful, the full cell batteries paired with nickel-manganese-cobalt oxide (NMC) or nickel-cobalt-alumina (NCA) as cathode will exhibit an improved capacity retention when compared with pure Li foil. This project will provide an example to design a new, reliable Li metal electrode with dendrite suppression by integrating 2D material design, simulation and electrochemical performance validation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.