Waste to wealth: Defect-rich Ni-incorporated spent LiFePO4 for efficient oxygen evolution reaction

Abstract

The development of efficient strategies to recycle lithium-ion battery (LIB) electrode materials is an important yet challenging goal for the sustainable management of battery waste. This work reports a facile and economically efficient method to convert spent cathode material, LiFePO 4 , into a high-performance NiFe oxy/hydroxide catalyst for the oxygen evolution reaction (OER). Herein, Ni-LiFePO 4 is synthesized via the wetness impregnation method and further evolves into defect-rich NiFe oxy/hydroxide nanosheets during the OER. The introduction of the Ni promoter together with in situ evolution strengthens the electronic interactions among the metal sites and creates an abundance of defects. Experimentally, the evolved Ni-LiFePO 4 delivers a low overpotential of 285 mV at 10 mA cm −2 and a small Tafel slope of 45 mV dec −1 , outperforming pristine LiFePO 4 and is even superior to the benchmark catalyst RuO 2 . Density functional theory (DFT) calculations reveal that the introduction of Ni effectively activates Fe sites by optimizing the free energy of the *OOH intermediate and that the abundance of oxygen defects facilitates the oxygen desorption step, synergistically enhancing the OER performance of LiFePO 4 . As a green and versatile method, this is a new opportunity for the scalable fabrication of excellent electrocatalysts based on spent cathode materials.

Engineering transition metal catalysts for large-current-density water splitting

“…In recent years, the first-row 3d transition metal compounds (TMCs) have been successfully developed and designed as advanced electrocatalysts for boosting water electrolysis. [25][26][27] With the tremendous endeavors devoted, the electrocatalytic performance of TMCs has been remarkably improved, which is even superior to commercial noble metal nanocatalysts. [28][29][30] In spite of the enormous enhancement in electrocatalytic performance observed in TMCs, their performance still can't meet the high requirement for industrial application.…”

Ni(OH)2 Nanosheets Grown on Reduced Graphene Oxide for Supercapacitor Electrodes

“…A much bigger specific surface area of battery-type materials can be acquired, with the development of nanomaterials. − Thus, the ion diffusion distance was shortened obviously, so the bulk redox reaction is basically changed to surface redox reaction. Most of the redox sites grow on the interface of electrode–electrolyte and have more scattering than in bulk materials, − so the reaction dynamic can be faster than in bulk materials, which leads to a capacitor-like response of nanosize battery materials. , As mentioned, nanosize materials are so-called extrinsic pseudocapacitance materials, which show battery-like behavior in bulk redox reaction and capacitor-like behavior reducing the size to nanoscales.…”

Recycling spent LiNi 1-x-y Mn x Co y O 2 cathodes to bifunctional NiMnCo catalysts for zinc-air batteries

“…LiNi 1-x-y Mn x Co y O 2 (NMC)-type cathodes are largely used in LIBs due to their high energy density and good electrochemical stability; therefore, bountiful Li, Ni, Mn, and Co metals in spent NMC cathodes can be recovered ( 12 – 14 ). Transition metals (e.g., Ni, Mn, and Co) usually exhibit promising bifunctional oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) performance ( 15 – 17 ). As one of the most promising energy storage devices, zinc-air batteries (ZABs) need the ORR/OER in the cathode side, which calls for low-cost bifunctional catalysts as cathode materials ( 18 – 20 ).…”

“…It is verified that the layered lithium transition metal oxides (typical cathode materials in LIBs) exhibit improved catalytic activity of OER after the delithiation process ( 33 – 36 ). In addition, with the modification of Ni, the spent LiFePO 4 cathode presents high OER performance because of the in situ evolution of Ni-LiFePO 4 active materials ( 16 ). Even though the spent cathode materials can be used as catalysts after modification, the large particle size limits their applications in ORR, and they are rarely studied in ZABs as cathode materials.…”