Nickel fluoride (NiF2)/porous carbon nanocomposite synthesized via ammonium fluoride (NH4F) treatment for lithium-ion battery cathode applications

Toward High Energy Density FeFx (x=2 and 3) Cathodes for Lithium‐Ion Batteries

“…The elaborate fluorination process allows for the direct fluorination of Co particles into nano‐CoF 3 particles, accompanied by an increase in nanoparticle size as the fluorination temperature increases [84,85] . Moreover, NiF 2 /porous carbon composites were obtained by direct mixing of NH 4 F with nickel precursors/porous carbon composites and heating at a certain of temperature under an inert atmosphere [86] . It was demonstrated that the above fluorination approach has good universality.…”

Metal Fluoride Cathode Materials for Lithium Rechargeable Batteries: Focus on Iron Fluorides

“…Typically, liquid-phase synthesis, including chemical precipitation, [60] hydrothermal, [61] solvothermal, [62,63] sol-gel, [64] and thermal decomposition methods [65] based on different fluorine sources, (hydrogen fluoride (HF) solution, [66] NH 4 F, [67] NH 4 HF 2 , [68,69] metal hexafluorosilicate, [70] F-containing ionic liquids (ILs), [71] etc.) has been utilized to prepare nanoparticle MFs, [72] metal oxyfluorides, [73] mixed metal difluorides, [74] and MF-carbon composites.…”

“…[16,17] In contrast, FeF 3 has the reversible ability with potential application value as a cathode for LIBs/LMBs, benefiting from its rhombohedral crystal structure (this can occur in intercalating reactions with one electronic transfer at the lattice unit) and the produced fine iron metal which connected to form a network of conductors. Additionally, other MFs, such as iron difluorides (FeF 2 ), [18] nickel fluorides (NiF 2 ), [19] cobalt fluorides (CoF 3 /CoF 2 ), [20,21] manganese fluorides (MnF 2 ), [22] and silver fluoride (AgF), [23] have also been researched for their respective advantages (Figure 1b). Therefore, the development of MFs on LIBs/LMBs increased rapidly in the past decade.…”

Design of a hydrolysis‐supported coating layer on the surface of Ni‐rich cathodes in secondary batteries

“…The rapid decrease in the cycle performance of high‐Ni LNCM materials is related to unwanted side reactions between the transition metal ions (especially Ni 4+ ) and the electrolyte: the highly activated Ni 4+ ions can accelerate the electrolyte decomposition, which not only leads to electrolyte depletion and formation of thick solid‐electrolyte interface (SEI) layers but is also associated with a phase transformation to inert rock salt structures (NiO) or spinel structures at the particle surface. In addition, because the ionic radius of Ni 2+ is similar to that of Li + , cation mixing occurs in which Ni ions are located in the Li layer 7‐11 . For this reason, Li that is not located in the Li layer reacts with CO 2 present in the air during the heat treatment process to form Li 2 CO 3 or reacts with water to form LiOH, which are referred to as residual Li compounds.…”

“…In addition, because the ionic radius of Ni 2+ is similar to that of Li + , cation mixing occurs in which Ni ions are located in the Li layer. [7][8][9][10][11] For this reason, Li that is not located in the Li layer reacts with CO 2 present in the air during the heat treatment process to form Li 2 CO 3 or reacts with water to form LiOH, which are referred to as residual Li compounds. Furthermore, when a high-Ni LNCM material is exposed to a humid environment, Ni 3+ on the surface changes to Ni 2+ , and the formation of residual Li compounds is accelerated, of which those present on the cover of the LNCM material cause the following problems.…”