Thesis Format
Integrated Article
Degree
Doctor of Philosophy
Program
Mechanical and Materials Engineering
Supervisor
Sun, Xueliang
2nd Supervisor
Zhou, Jigang
Co-Supervisor
Abstract
The increasing demand for energy storage in recent years requires higher energy of lithium-ion batteries (LIBs). Layered oxide cathode and silicon (Si) anode have been considered as promising electrode candidates owing to their high specific capacities and ideal working voltages. However, their development has been plagued by persistent surface degradation and structural fatigue issues. Layered oxide cathodes experience abrupt strain accumulation caused by inherent anisotropic lattice changes, leading to the generation of intergranular and intragranular cracking. Moreover, their intrinsic high reactivity with electrolyte at the highly delithiated state suffers from serious surface reconstruction, including interfacial side reaction and phase transition. In terms of the anode, large volume change and deteriorated solid-electrolyte interphase of Si anode result in the pulverization of Si particles and the increase in cell impendence. Thus, this thesis mainly concentrates on the advanced interface design to tackle the challenges of next-generation layered oxide cathode and Si anode materials.
Firstly, high-voltage stable amorphous phosphate synthesized by atomic layer deposition (ALD) technique has been applied for boosting high-performance 4.5V-LiCoO2 cathode via atomic-level manipulation of surface chemistry. The lithium zirconium phosphate (LZPO) coating can effectively block lattice oxygen release and alleviates Co redox reaction heterogeneity at high cutoff voltage. Secondly, a cost-effective Al based surface chemistry strategy through ALD and molecular layer deposition (MLD) has been developed to mitigate the interface issues for nickel-rich cathode. LiNi0.94Co0.05Mn0.01O2 with excellent interface stability exhibits competitive cycling performance and rate capability. Thirdly, all-solid-state batteries (ASSLBs) adopting nickel-rich cathode is investigated and a precisely tailored molecular-level Li-Zr-Al based (LZA) inorganic-organic surface reconstruction was proposed via MLD. The robust LZA layer with the features of high anti-corrosion and strain-retardant tolerances facilitates a substantial cycling stability of LiNi0.83Co0.11Mn0.06O2 in sulfide-based ASSLBs. Finally, a bi-functional graphite fluoride framework has been proposed for Si anode to simultaneously address its volume change and unstable interface. Benefiting from the in-situ formed a F-rich interface, an outstanding cycling stability with 980.7 mAg g-1 in 1000 cycles was achieved.
The main contribution from this thesis includes: 1) A series of novel, facile, efficient, and cost-effective coating strategies have been developed in this thesis to tackle the electro–chemical–mechanical issues of high-energy electrode materials. 2) The interface properties and required characteristics, such as interface ion/electron transport, near surface structures, and electrochemical stability, have been identified through comprehensive mechanism study using advanced characterization methods. 3) Excellent electrochemical performance is achieved and the potential to develop LIBs with high energy-density and safety is demonstrated from liquid-based batteries to next-generation all-solid-state batteries.
Summary for Lay Audience
The large-scale development of electric vehicles (EVs) is growing tremendously to tackle climate change and the ever-increasing energy crisis. Lithium-ion batteries (LIBs) as power sources are expected to simultaneously meet the requirements of high powder and energy density. Layered oxide cathode and silicon (Si) anode are promising electrode candidates with high energy density for LIBs to relieve range anxiety for EVs. However, both layered oxide cathode and Si anode still face serious issues, including huge volume change during cycling and unstable interphase formation due to the parasitic side reactions between electrode and electrolyte. These challenges limit their practical application in EVs. This thesis mainly concentrates on the advanced interface design to tackle the challenges of layered oxide cathode and Si anode materials.
Firstly, a high-voltage stable lithium zirconium phosphate (LZPO) coating layer is synthesized via atomic layer deposition (ALD). The LZPO coated LiCoO2 cathode can further extend the energy density and cycling stability of LiCoO2 to a much higher level. Secondly, a cost-effective and facile Al-based surface modification strategy has been deposited for Ni-rich cathode through a combination of ALD and molecular layer deposition (MLD). It enables superior cycling stability with over 90% retention after 200 cycles owing to the stabilized interface. Thirdly, a novel inorganic-organic coating is developed for Ni-rich cathode in solid-state batteries to mitigate the issues including mechanical failure, contact loss, and interface ion transport. The protected cathode exhibited a superior capacity retention of 87.8% in a long-term operation for 1000 cycles. Finally, a facile and effective multi-functional framework strategy is proposed to tackle the volume change and unstable interface at same time in Si anode for achieving a stable long-cycling performance.
The main contribution from this thesis includes: 1) Our study provides advanced interface design to realize high-stable, tunable, facile, and cost-effective coating strategy to mitigate the challenges in electrode materials. 2) Deep insights for how coating layers influence electrochemical performance are illustrated in our research, including mechanical evolution, interface ion/electron transport, and interface electrochemical stability. 3) The potential for next-generation LIBs with high energy-density is released from liquid-based batteries to solid-state batteries by our strategy.
Recommended Citation
Ma, Jinjin, "Advanced interface design for electrode materials in high energy-density lithium-ion batteries" (2024). Electronic Thesis and Dissertation Repository. 10547.
https://ir.lib.uwo.ca/etd/10547