Advanced interface design for electrode materials in high energy-density lithium-ion batteries
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.