Materials Design and Investigation of Ni-rich Cathode for Li-ion Batteries

Abstract

With the explosive demands for the energy storage systems, lithium-ion batteries (LIBs) received great attention. Among various cathode materials, nickel-rich cathode materials have been one of the promising candidates due to their high gravimetric energy density and low costs. However, Ni-rich material still faces various challenges such as phase transition, micro-crack evolution, residual lithium compounds, gas evolution, which can be detrimental to battery performance. Accordingly, herein, I have covered introduction of Ni-rich cathode material and various strategies to mitigate the intrinsic challenges in the Chapter 1.

In the Chapter 2, I proposed a structurally stable with macrovoid nickel-rich material, using the affordable, scalable, and one-pot co-precipitation method without using surfactants/etching agents/complex-ion forming agents. The strategically developed macrovoid induced cathode via self-organization process exhibits excellent full-cell rate capability, cycle life at discharge rate of 5 C, and structural stability even at the industrial electrode conditions, owing to the fast Li-ion diffusion, internal macrovoid act as ‘buffer zones’ for stress relief , and highly stable nanostructure around the void during cycling. In the Chapter 3, I proposed an intrinsic limitations of polycrystalline nickel-rich cathode materials in high-energy full-cell, discovered under the industrial electrode fabrication conditions. Owing to its highly unstable chemo-mechanical properties, even after the first cycle, nickel-rich materials are degraded with a longitudinal direction of the high-energy electrode. This inhomogeneous degradation of nickel-rich materials in the electrode level is originated from the overutilization of the active materials on the surface side, causing severe non-uniform potential distribution during the long-term cycling. This study regarding the degradation of polycrystalline nickel-rich materials, therefore, suggests the adoption of robust single crystalline Ni-rich cathode, as a feasible alternative, to effectively suppress the localized overutilization of active materials.

In the Chapter 4, I proposed a proper approach for utilizing Ni-rich particle with solid electrolyte by providing multiple channel system for the lithium ion transport. This work shows comparison of electrochemical performances between convention Ni-rich material with advanced Ni-rich material with multiple channel system. As a result, we expect that this research could provide insights on development directions for the cathode material for the all-solid-state lithium-ion batteries.