Interfacial strategies for improved solid-state lithium batteries

Thesis

This project aims to help facilitate the step change in battery energy density (per volume) needed for improved consumer electronics and greatly increased electric vehicle adoption. The work in this thesis is focussed on enabling a lithium metal electrode to be successfully employed in a rechargeable battery as a negative electrode by using a protecting solid electrolyte.

In Chapter 4, the viability of using a solid-electrolyte (Li3N) to protect a lithium metal anode is explored and the phenomena that occur at this metal/ceramic interface during the passage of current are determined.

Chapter 5 explores a novel strategy of using a solid-electrolyte (Li3N) as a separator in a solid-electrolyte/liquid-electrolyte hybrid battery. By using liquid electrolyte, the cathodic instability of Li3N, as well as the volume expansion issues of cathodes with solid-electrolytes and the self-discharge problems associated with Li3N should theoretically be eliminated. The universality of solid-electrolyte/liquid-electrolyte interfacial phenomena are also examined by investigating an alternative solid-electrolyte (LLZTO) with a state of the art liquid-electrolyte used in commercial Li+ ion batteries (LP30).

Chapter 6 explores the chemistry of Li3N·P2S5 solid-electrolytes, as it is speculated that the electrochemical reduction of a nitrogenous electrolyte would form an SEI rich in Li3N, and would therefore produce self-healing and low resistance SEIs in contact with Li.

Authors: Hartley, G

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: lithium nitridothiophosphate; nitride electrolyte; SSB; lithium metal anode; SLEI; dendrite; critical current density
• Subjects: Lithium ion batteries; Solid state batteries; Electric vehicles