Innovative three-dimensional scaffold engineering for enhanced Lithium metal battery performance

Abstract

Lithium (Li) metal is regarded as a highly promising negative electrode material for high-energy-density batteries, due to its remarkable theoretical specific capacity and low redox potential. However, the practical application of Li metal batteries (LMBs) is challenged by the dendrite formation, infinite volume expansion, and fragile solid electrolyte interphase (SEI) of the Li metal electrode. To solve these issues, various strategies have been devoted, including artificial protection layers, three-dimensional scaffolds and functional electrolytes, with aims of stabilizing the structural integrity and mitigating the side reactions of Li metal electrode. Although considerable improvements have been achieved via these strategies, the practical application remains elusive. Confining Li deposition within a three-dimensional host is commonly adopted to suppress the Li dendrite growth and volume expansion of the Li electrode. Nevertheless, the sluggish Li+ transfer and high Li nucleation barrier on the skeletons can result in uneven distribution of deposited Li in the hosts, thereby hindering their application in practical conditions. Consequently, conception of functional modification within three-dimensional scaffolds to promote uniform Li metal deposition throughout the entire skeleton is becoming a surging demand for achieving practical LMBs.
In this thesis, we design and study the functional modifications of three-dimensional hosts for simultaneously accelerating Li+ transportation, adjusting electron/Li+ charge transfer rates, and reducing Li nucleation barriers, leading to homogenized Li deposition inside the pore space of host. These achievements enable both the liquid and solid LMBs with enhanced electrochemical performances. The specific research contents are summarized below:

1.Design of Hierarchical Host Structures Enables Regulated Lithium Deposition for Stable Lithium Metal Electrodes:
This work proposes a novel hierarchical host structure featuring a multifunctional secondary porous architecture to regulate inner Li growth with high uniformity and reversibility. The secondary porous structure composed of carbon nanotubes (CNTs), nickel (Ni) and Li2O-enriched SEI is in-situ generated through lithiation reaction of a modified Ni foam scaffold. This structure exhibits high lithiophilicity, rapid Li+ transportation and charge transfer. The LMBs utilizing this rationally designed Li metal composite electrode can achieve stable cycle performance over 300 cycles with a practical LiFePO4 positive electrode (~2.5 mAh cm-2). This research provides an innovative approach to designing host microstructures and contributing to the development of more stable Li metal electrode in practical liquid LMBs.

2.Three-Dimensional Li+ Conductive Networks for Enhanced Li⁺ Transportation in Liquid and Solid Batteries:
In this work, we successfully construct a three-dimensionalized electronic insulation and robust nanodiamond (ND) network on carbon paper (CP) using chemical vapor deposition. The structure not only impedes electron transportation, thereby preventing undesired Li top precipitation, but also demonstrates remarkable Li mobility and affinity, facilitating efficient in-depth Li+ transportation throughout the skeleton. Based on the superior properties of this three-dimensional ND network, the performance of the Li metal electrode within CP@ND significantly surpasses that of conventional carbon-based hosts, especially under lean-Li conditions. Moreover, the implementation of CP@ND dramatically enhances the cycling stability of all-solid-state LMBs, providing a novel approach for safeguarding Li metal electrodes in environments with limited electrolyte mobility.

3.Bulk Kinetic Engineering of Lithium Electrodes in Practical All-Solid-State Batteries:
In this work, we synthesize a Zeolitic Imidazolate Framework (ZIF) derived layer (ZDL) on the skeleton of the copper mesh (CM) through the adsorption and self-assembly of Zn(NO3)2 and 4,5-dichlorimidazole. After an annealing process of the CM@ZDL composite, the ZDL layer can be further tailored with particular chemical composition and high lithiophilicity. These properties enable a distinct conversion process of the annealed CM@ZDL composite in molten Li, enabling the formation of an advanced composite Li electrode with lithium chloride (LiCl) in the bulk phase. The presence of LiCl significantly facilitates Li+ transportation in the bulk phase of Li electrode, which is further demonstrated as an important feature to improve the interface stability and cyclic performance of all-solid-state LMBs. Remarkably, even under the conditions of high positive electrode loading or high rates, the all-solid-state LMBs using LiCl incorporated Li electrode still exhibit promising long-term cyclic performances. Compared to previous efforts mainly focusing on the Li/electrolyte interfacial engineering for stabilization of all-solid-state LMBs, this work opens up an alternative and efficient approach based on the bulk phase structuration of three-dimensional Li composite electrode for practical high-energy-density all-solid-state LMBs.

Date of Award	15 Oct 2025
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Di Hu (Supervisor), Haiyong He (Supervisor) & George Zheng Chen (Supervisor)