Recent Advances in Cobalt-Free Nickel-rich Li-ion Battery Cathode Materials for Next Generation Electric Vehicles

Abstract

Recently, battery research community has been grappling with the burgeoning question of ensuring sustainability in battery technologies that would enable next generation electric vehicles. In the past decade, extreme cobalt price fluctuations have severely constrained the supply chains of battery manufacturing industries as most mainstream lithium ion batteries still largely employ cobalt containing cathode materials. To keep battery costs low to ~80$/kWh, and to ensure a sustainable future for electric vehicles, a multitude of research efforts have been directed towards exploring nickel rich cathode chemistries boasting high capacities >200 mAh/g. Though the question of sustainability is not completely addressed through the use of nickel rich compositions, these systems still remain the most promising alternatives when considering the performance requirements of modern electric vehicles. In this context, our team has been exploring the development of novel classes of layered lithium ion battery cathode materials with '0' cobalt in their compositions. Our team has systematically investigated new classes of cobalt-free nickel-rich battery cathodes, having the general formula, LiNixM1yM2zO2 (where, M1 and M2 are other metal ions, x + y + z = 1)[1,2] and evaluated their performance in the quest of identifying the best nickel rich variant. These layered nickel-rich cobalt-free cathodes have similar crystal structure and properties to conventional cobalt containing cathodes such as NCMs and NCAs while delivering comparable and in some cases better electrochemical performance. Here, I will present our research efforts in the development of these novel cathode formulations starting from compositional landscape investigations, advanced characterizations followed by electrochemical performance assessments. Specifically, in-situ high temperature X-Ray and Neutron diffraction techniques were employed to investigate the calcination and phase formation behavior while operando investigations using X-Ray diffraction and Mössbauer spectroscopy were employed to obtain a mechanistic understanding of the redox behavior exhibited by these systems. Best performing compositions were upscaled in continuous stirred tank reactors to kilogram levels, following which, slot-die coating process was employed to fabricate electrodes that were later assembled in pouch format full cells for electrochemical performance assessments[3]. The work presented here summarizes recent results of this early stage research and development endeavor to highlight the immense potential that these nickel-rich class of cathodes can offer towards development of next generation cost effective lithium ion batteries for electric vehicle applications in the coming decades.