Unveiling olivine cathodes for high energy-density lithium-ion batteries: a comprehensive review from the atomic level to the electrode scale

Abstract

The development of cathode materials for lithium-ion batteries (LIBs) aims to achieve high energy density, cost-effectiveness, and thermal as well as mechanical stability. It generally proceeds through multidimensional design rules at the atomic, phase, particle, and electrode levels. Recently, new strategies have been proposed to achieve high energy density even in olivine-structured cathodes, which have a relatively lower theoretical capacity compared to layered cathode materials. These strategies involve substituting iron (Fe) with manganese (Mn), controlling particle morphology, and fabricating thick electrodes to simultaneously achieve high energy density and cost-effectiveness. However, comprehensive design guidelines for the material design, particle morphology, and fabrication of thick electrodes for olivine cathodes are still lacking. Herein, we provide detailed insights from well-established prior knowledge on olivine cathodes and share the latest findings related to their particle morphology control and electrode thickening. Additionally, our review closely investigates further considerations related to kinetics, such as low electronic and ionic conductivity, and mechanical instability issues that arise while thickening electrodes. It is emphasized that these issues can be resolved through a comprehensive understanding and strategies from the atomic level to the electrode level. Therefore, this review aims to contribute to achieving high energy density in olivine-based cathodes by understanding their kinetic limitations and mechanical instabilities. We propose unifying strategies for the development of high-energy, low-cost, long-lasting olivine cathodes through atomic to electrode level engineering, focusing on: (1) high energy densities, (2) kinetics, and (3) structural stabilities.