Fluorophosphates: Next Generation Cathode Materials for Rechargeable Batteries

Abstract

steadily depleting. These realities have triggered significant efforts to harness renewable energy sources like hydro, solar, geothermal, or tidal energy that are intermittent in nature. Economic and sustainable energy storage devices can be coupled with renewable energy generators to realize uninterrupted energy supply. In this sector, rechargeable batteries form the most viable energy storage devices. Today, lithium-ion batteries dominate the electronics market due to their high volumetric and specific energy density. [1-5] The manifold consumption of lithium resources due to the booming multibillion-dollar industry and limited global lithium reserves have raised concerns over the future supply of Li-based precursors to cater to the large scale production of lithium-ion batteries. To alleviate this issue, various alternatives using earth-abundant elements (e.g., monovalent Na + /K + and multivalent Mg 2+ /Ca 2+ /Al 3+) have been proposed to replace LIBs. [6-10] The energy density of batteries is limited by the performance of cathodes. Thus, over the last five decades, three major types of insertion materials have been examined as cathodes for secondary batteries: layered transition metal oxides, Mn-based spinels, and polyanion type materials (Figure 1a). 2D layered transition metal oxides have been extensively studied, but issues like oxygen loss at high potentials raise safety concerns and hence oxides like LiCoO 2 or LiNi 1−x−y Co x Mn y O 2 (x < 1, y < 1) are mainly limited to small portable electronics. Though oxides deliver high energy density, they have lower redox potentials due to highly covalent MO bonding character. [11] This issue can be evaded by implementing 3D polyanionic cathode materials with tuneable (high) redox potential along with structural/thermal stability leading to safe battery operation. [12,13] Plethora of insertion materials have been reported with different polyanionic subunits [(XO 4

Fluoro(Phosphates,Sulfates) or (Phosphate,Sulfate) Fluorides: Why Does It Matter?

“…The fluoride phosphate compounds for rechargeable batteries have been nicely reviewed recently by Sharma et al. [ 15 ] and sulfate fluorides, on the other hand, have been reviewed by Rousse and Tarascon [ 16 ] few years ago.…”

“…The fluoride phosphate compounds for rechargeable batteries have been nicely reviewed recently by Sharma et al [15] and At this point, one could ask: why this really matters, why it is worth discussing chemical nomenclature inaccuracies in Advanced Energy Materials and why it has not been needed until now?…”

Low‐Cost Polyanion‐Type Sulfate Cathode for Sodium‐Ion Battery

“…In recent decades, with the development of large‐scale industrialization, traditional fossil fuels such as coal, oil, natural gas, and other nonrenewable energy sources have been rapidly consumed, leading several huge issues, including resource exhaustion, environmental deterioration, the greenhouse effect, acid rain, pollutant haze, and so on. [ 1–5 ] Environment friendly and renewable energy need to be developed urgently. [ 6–8 ] The traditional renewable energy systems, however, such as solar energy, wind energy, geothermal energy, and tidal power, are limited by geographical location, and intermittent and unstable voltage output, so that they cannot effectively solve current energy problems.…”

A Comparative Study on Na2Fe0.6Mn0.4PO4F/C Cathode Materials Synthesized With Various Carbon Sources for Na-ion Batteries

“…Among these fluorophosphate materials, Na 2 MnPO 4 F is attracting significant attention due to its optimal theoretical capacity and suitable working potential. Firstly, the theoretical specific capacity of Na 2 MnPO 4 F is as high as 250 mAh g −1 when the two sodium-ions are completely removed (~125 mAh g −1 for one sodium-ion) (Wu et al, 2018b ; Sharma et al, 2020 ). Secondly, based on the strong induction effect and strong negative charge of F − , Na 2 MnPO 4 F owns high working potential (3.66 and 4.67 V vs. Na/Na + ) and excellent thermal stability (Wu et al, 2018b ), and its working potential is within the stable window of electrolytes.…”