Advanced Hybrid Materials for High-Energy Density Storage: Fundamentals and Design
Abstract
The primary aim of this project is to develop computational materials design approaches to speed-up the design of anode materials with high specific capacity and electrochemical stability for the next-generation of electric-vehicle’s batteries. The project has received financial support from Vetenskapsrådet (VR), through the “Young Researcher Grant” awarded to the PI of this project, and from the Swedish Energy Agency. The strategy is to target stable electrochemical interfaces made of lithium metal protected by polymer membranes. The specific goals are:
(i) To achieve fundamental understanding on the underlying mechanisms of the reactivity on the lithium metal-electrolyte interfaces, unveiling the atomic-level properties that govern the electrochemical stability.
(ii) To develop a novel high-throughput computational materials design (HCMD) approach, incorporating ionic conductivity in the materials screening step to search for stable electrochemical interfaces.
Li-ion batteries have provided a lot of advancement to the mobile devices since its first commercialization in 1990 [1]. Now, new Li-battery concepts are emerging with the potential to meet the high-energy storage requirements (250 Wh/Kg and 800 Wh/l) of electric vehicle [2]. The popularization of such technology is a route to enable a sustainable world growth with reduced impact on the environment. However, there are many challenges facing these technologies, and in particular they still depend on the development of stable Li-metal anode for successful commercialization. We have initiated the investigation of Li metal degradation pathways at relevant metal-electrolyte interfaces and have built-up the knowledge on theoretical methodologies based on first-principles theory (using Density Functional Theory - DFT) suitable for studying these systems. The project moves now to the stage of investigating electrochemical properties of lithium metal-polymer interfaces and ionic conductivity mechanism across the interface. We are seeking multifunctional co-polymers that meet at the same time the properties of electron-insulating and ion-conducting and which forms stable electrochemical interface with Li metal. The ultimate goal is to establish the compostion-structure-properties relationships unveiling fundamental descriptors for the high-throughput (HT) screening. To incorporate the ion transport into the HT-screening, which is a challenging problem, our strategy is to employ metadynamics simulations for the assessment of the free energy profile of the ion transport. A first target molecule in this study will be poly(4-bromostyren) and co-polymer with methoxypolyethylene glycol maleimide to enhance ionic conductivity. As a second step, we will build a wide library of co-polymer candidates (including existing and hypothetical compounds) adding key properties that will be calculated from accurate DFT. We will start by calculating the key properties of template polymers like poly(4-bromostyren) and polyethylene oxide and then compose a large amount of co-polymers playing with three different heteroatoms (viz. N, O and S) and many functional groups. Different copolymer arrangements will be evaluated for a given A and B building blocks. The HT screening will follow the hierarchy of stability –> suitable level potentials –> appropriate ionic conductivity –> surface attachment energy.
Reference:
1. Tarascon, J.-M. & Armand, M. Nature 414, 359–367 (2001).
2. Bruce, P. G. et al. Nature Materials 11, 19–29 (2012).
