Interface Design and Electrolyte Engineering for Highly Reversible Metal-Based Batteries

Abstract

Battery technologies have been revolutionizing industries and our daily lives. As energy storage and conversion systems, batteries are playing the role of transitioning the source of energy from fossil fuel dependence to renewable-fuel dominance. Battery-powered electric vehicles are replacing petrol vehicles, which has been intensifying the need for batteries with high energy density. Lithium metal batteries (LMBs) are regarded as such a potential candidate, which could achieve an energy density of up to 500 Wh kg−1. The main drawbacks for LMBs are severe corrosion of Li metal during air exposure, dendrite growth induced short-circuit risk, excessive side reaction between Li metal and electrolyte, and poor battery life. Large-scale energy storage is essential for renewable energy such as solar and wind to balance electricity supply and demand. Zinc ion batteries (ZIBs), featured with safety, low cost and environment-friendliness, are promising in this field. However, real applications of ZIBs are hindered by unwanted dendrite growth, Zn corrosion, cathode material degradation, insufficient temperature adaptability and electrochemical stability window (ESW). This Thesis aims to optimize the battery performance of LMBs and ZIBs, especially anode reversibility and cathode stability, via electrode/electrolyte interface modification and electrolyte design. In this Thesis, a systematic literature review is provided in Chapter 2 covering the most advanced strategies of artificial protection layer design for LMBs, in the category of mono-component inorganic layers, reactive inorganic layers, hybrid inorganic layers, polymer-like inorganic layers, polymer layers, and inorganic-organic composite layers. Chapter 2 also includes a review of the ZIBs electrolyte design, with the aspects of optimizing the compatibility between cathode materials and electrolytes, inhibiting anode corrosion and dendrite growth, extending electrochemical stability windows, enabling wearable applications, and enhancing temperature tolerance. Chapter 3 focuses on designing a protection layer on the Li metal surface. A silane coupling agent is used as the adhesion promoter to address the adhesion issue between the SEI layer and Li metal anode, and as a protection layer to avoid the Li metal from corrosion by air. This design provides a promising pathway for the development of Li metal electrodes that will be stable both in electrolytes and in the air. Chapter 4 proposes a hybrid electrolyte (HE) with dimethylacetamide (DMAC), trimethyl phosphate (TMP) and H2O as the solvent for ZIBs. We show that the strong polar DMAC and TMP molecules have a significant impact on H2O to strengthen the O−H bonds and suppress activity. We evidence that the hybrid electrolyte obviates anode corrosion, extends operation temperature, guides the (002) plane preferred orientation during Zn plating, and is compatible with the high-voltage cathode. Chapter 5 investigates the different electrochemical performances of sodium vanadate in the hybrid electrolyte and the aqueous electrolyte. It is observed that the structural stability of the NaV3O8·1.5H2O cathode is significantly improved during continuous charging/discharging if fewer water molecules are included in the Zn2+ solvation structure. This is the reason accounting for the longer lifespan of Zn||NaV3O8·1.5H2O cell obtained in the HE compared to that in aqueous electrolyte.