This project is part of a 4 year Dual PhD degree programme between the National Tsing Hua University (NTHU) in Taiwan and the University of Liverpool in England. As Part of the NTHU-UoL Dual PhD Award students are in the unique position of being able to gain 2 PhD awards at the end of their degree from two internationally recognised world leading Universities. As well as benefiting from a rich cultural experience, Students can draw on large scale national facilities of both countries and create a worldwide network of contacts across 2 continents.
1. Li dendrite striping/plating behavior to hybrid structure electrolyte
2. Degradation mechanism between solid electrolyte/high-voltage cathode.
2. Outline of background:
Transportation has been the largest source of climate pollution in the world, the automotive revolution- electric vehicles (EVs)- can make our roads as clean as possible. To obtain higher energy density, operation voltage, and chemical safety on Li-ion batteries, solid-state lithium (Li) metal batteries (SSLMBs) have become a research focus in the energy storage field. The Li metal anode has a high specific capacity of 3860 mAh/g and offers the lowest redox potential (−3.040 V versus H+/H2), allowing for an unprecedented energy density. However, the Li dendrite limits the development of Li metal batteries and raises the issue of cycle lifetime and safety accidents. Emerging solid-state electrolytes (SSE) with high ionic conductivity such as oxide garnet ceramics Li7La3Zr2O12 (LLZO) have drawn attention to inhibit dendrite formation due to its high shear modulus compared to gel-type polymers electrolytes. However, purely ceramic pellets or sheets are brittle, which prevents its application on EVs. Hybrid LLZObased/polymer solid composite electrolytes (SCEs) realize the complementary strengths from ceramic LLZO and polymers. The polymer matrix improves the flexibility and wettability to electrode, and the LLZO particles also elevate the ionic conductivity and critical current density (CCD). Moreover, the composite structure can be further controlled in order to meet different cathode and anode requirements such as “Lithiophilic or Lithiophobic” modified surface, the striping/plating behavior under different structures of SCEs has not been well investigated. The other hotspot is the interface between electrolyte and high voltage cathode with high-capacity nickel (Ni)-rich ternary cathode, such as LiNi0.5Co0.2Mn0.3O2 (NCM523), LiNi0.6Co0.2Mn0.2O2 (NCM622) or LiNi0.8Co0.1Mn0.1O2 (NCM811). High Ni concentration encounters the “Li/Ni cation mixing effect” at the ternary compound surface. The degradation mechanism and interaction with solid electrolytes with different interface modifications or composite structure tuning still need a systematic study. The Operando combing in-situ and ex-situ observation reveals the interfacial kinetics on those important topics, we suggest that this project could enable researchers to deepen their understanding of Li metal batteries.
3. Proposed research methodology:
Hybrid structure on solid-polymer electrolytes with thin film modification
1) Li dendrite striping/plating behavior; 2) Degradation mechanism
2) NTHU: Sample fabrication & preliminary electrochemical characterization
Solid: Al: LLZO, Ta: LLZO and Ga: LLZO micrometer/nanometer-scale particles; LLZO thin film
Polymer: poly(ethylene oxide) (PEO) and poly(vinylidene fluoride) (PVDF-HFP)
Test cell structure: Li| SPEs |Li, Ni-rich ternary cathode| SPEs |Li
UoL: Operando & in-situ observation
Advanced cryoFIN + LN2 stage, Operando gas, liquid, heating stages to image both the atomic-scale structure of materials and the progression of dynamic processes controlling diffusion, energy transport, and degradation
For academic enquires please contact Layla Medhi (B.L.Mehdi@liverpool.ac.uk) or Tzu-Ying Lin (email@example.com)
For enquires on the application process or to find out more about the Dual programme please contact firstname.lastname@example.org
To apply please visit: https://www.liverpool.ac.uk/study/postgraduate-research/how-to-apply/ and click on the 'Ready to apply? Apply onl'ne' button, to start you application. When applying please ensure you Quote the supervisor & project title you wish to apply for and note ‘NTHU-UoL Dual Scholarship’ when asked for details of how plan to finance your studies.
This project is a part of a 4-year dual PhD programme between National Tsing Hua University (NTHU) in Taiwan and the University of Liverpool in England. It is planned that students will spend 2 years at NTHU, followed by 2 years at the University of Liverpool.
Both the University of Liverpool and NTHU have agreed to waive the tuition fees for the duration of the project and stipend of TWD 11,000/month will be provided as a contribution to living costs (the equivalent of £280 per month when in Liverpool).