Metal–Organic Framework-Derived Nanoconfinements of CoF₂ and Mixed-Conducting Wiring for High-Performance Metal Fluoride-Lithium Battery

Abstract

Metal fluoride (MF) conversion cathodes theoretically show higher gravimetric and volumetric capacities than Ni-or Co-based intercalation oxide cathodes, which makes metal fluoride−lithium batteries promising candidates for nextgeneration high-energy-density batteries. However, their highenergy characteristics are clouded by low-capacity utilization, large voltage hysteresis, and poor cycling stability of transition MF cathodes. A variety of reasons is responsible for this: poor reaction kinetics, low conductivities, unstable MF/electrolyte interfaces and dissolution of active species upon cycling. Herein, we combine the synthesis of the metal−organicframework (MOF) with the low-temperature fluorination to prepare MOF-shaped CoF 2 @C nanocomposites that exhibit confinement of the CoF 2 nanoparticles and efficient mixed-conducting wiring in the produced architecture. The ultrasmall CoF 2 nanoparticles (5−20 nm on average) are uniformly covered by graphitic carbon walls and embedded in the porous carbon framework. Within the CoF 2 @C nanocomposite, the cross-linked carbon wall and interconnected nanopores serve as electron-and ion-conducting pathways, respectively, enabling a highly reversible conversion reaction of CoF 2 . As a result, the produced CoF 2 @C composite cathodes successfully restrain the above-mentioned challenges and demonstrate high-capacity utilization of ∼500 mAh g −1 at 0.2C, good rate capability (up to 2C), and long-term cycle stability over 400 cycles. Overall, the presented study not only reports on a simple composite design to achieve high-energy characteristics in CoF 2 −Li batteries but also may provide a general solution for many other metal fluoride−lithium batteries.

Exploiting the Iron Difluoride Electrochemistry by Constructing Hierarchical Electron Pathways and Cathode Electrolyte Interface

“…[ 7,11,21,32,36 ] In rate test, the CAM@Al electrode was poor both in capacity retention and release. We summarized the recent state‐of‐the‐art studies about MFs including FeF 3 , [ 36 ] FeF 2 , [ 7,11,14,16,21,37 ] and CoF 2 [ 38 ] in terms of cycle life and current density (Figure 2D). More details of electrochemical performance in comparison with other studies are summarized in the Table S2, Supporting Information.…”

Recent Progress in Quasi/All-Solid-State Electrolytes for Lithium–Sulfur Batteries

“…With the growing demands for global energy, high-energy-density and long-cycling batteries are broadly developed and play a growing role in the global energy system (Wu et al, 2021). A rechargeable Li battery based on the Li chemistry is considered a promising candidate for battery systems and related functions.…”

Iron Phosphide Confined in Carbon Nanofibers as a Free-Standing Flexible Anode for High-Performance Lithium-Ion Batteries

“…However, the drawbacks also lie in the intercalation materials, particularly the anodes such as most commonly used graphite and lithium titanate (Li 4 Ti 5 O 12 ) , delivering low specific capacity at their theoretical limits. To increase energy density and reduce cost, next-generation LIBs will likely rely on the development of conversion materials produced from earth-abundant elements such as iron (Fe), silicon (Si), and phosphorous (P). − Over the past decade, Si and P have been extensively studied as alloy-type conversion anodes due to their ultrahigh theoretical specific capacities (4212 mA h g –1 for Si and 2596 mA h g –1 for P), , but both of them suffer from large volume changes of ∼300% during lithiation, , which could limit cycle life or result in safety issues.…”