Cost, safety, and cycle life have emerged as prime concerns to build robust batteries to cater to the global energy demand. These concerns are impacted by all battery components, but the realizable energy density of lithium-ion batteries (LIBs) is limited by the performance of cathodes. Thus, cathode materials have a significant role to play in advancing the performance and economics of secondary batteries. To realize next generation Li-ion and post Li-ion batteries, a variety of cathode insertion materials have been explored, but finding a cost effective and stable cathode material that can deliver high energy density has been a daunting task. Oxide cathode materials are ubiquitous in commercial applications, as they can deliver high capacity. In comparison, polyanionic insertion materials can offer tuneable (high) redox potential, operational safety, and structural as well as thermal stability. Indeed, a wide range of polyanionic materials like phosphates, borates, sulfates, and their complexes have been reported. In this article, the alkali metal fluorophosphates class of polyanionic cathodes for secondary batteries is discussed. The various reported fluorophosphate insertion materials are discussed in terms of their electrochemical and electrocatalytic properties. The historical overview, recent progress, and remaining challenges for polyanionic fluorophosphates are presented along with suggested future research directions and potential application.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: L.S. is grateful to the Ministry of Human Resource Development (Govt. of India) for a doctorate fellowship. He also thanks the Electrochemical Society (ECS, USA) for a 2020 ECS Summer Fellowship. P.B. acknowledges the financial support from the Technology Mission Division (Department of Science and Technology, Govt. of India) under the Materials for Energy Storage (MES-2018) program (DST/TMD/MES/2k18/207). Research reported in this publication was partially supported by King Abdullah University of Science and Technology (KAUST). The material structures were illustrated using VESTA software.