Insights into the Enhanced Catalytic Activity of Fe-Doped LiCoPO₄for the Oxygen Evolution Reaction

Abstract

Developing highly active and stable catalysts for the oxygen evolution reaction (OER) is of significant importance for numerous electrochemical energy conversion devices. Previous accomplishments have shown that LiCoPO 4 is a promising catalyst for OER activity; however, its activity and stability at high potential still need improvement to meet the requirements of practical applications, and further studies are needed for its catalytic mechanism. Here, we report a series of Fe-doped LiCoPO 4 materials that exhibit excellent OER catalytic behaviors at high potential and elucidate their catalytic mechanism. Fe-doping enhances the OER activity through synergistic coupling effects, which is strongly influenced by the divalent Co 2+ and Fe 2+ cations rather than the trivalent Co 3+ and Fe 3+ cations. The possible rate-determining step is proposed to be the formation of *OOH derived from *O based on the H/D kinetic isotopic effect experiment.

One-Step Synthesis of LiCo1-1.5xYxPO4@C Cathode Material for High-Energy Lithium-ion Batteries

“…However, the continuous oxidative decomposition of electrolyte [ 11 , 12 ] and the unstable cathode electrolyte interface [ 13 , 14 ] under 5 V high voltage caused by Co 2+ /Co 3+ , resulting in rapid capacity degradation during cycling, severely hindering the application of LiCoPO 4 cathode material. In addition, the Li/Co antisite exchange during the cycling process [ 15 , 16 , 17 ] and low intrinsically ionic and electronic conductivity [ 18 , 19 , 20 ] must also be overcome.…”

“…Lots of work have been undertaken to solve these problems, including decreasing the cathode particle size and controlling the morphology to shorten the Li-ion migration distance [ 21 , 22 , 23 , 24 ]; coating the cathode particle with stable materials [ 25 , 26 , 27 , 28 ] or conductive materials [ 29 , 30 , 31 , 32 , 33 ] to stabilize the interface and reduce the side reaction; partial substitution at Co site [ 20 , 34 , 35 , 36 , 37 ] to improve the intrinsic ionic and electronic conductivity [ 34 , 35 , 38 , 39 , 40 ]; and adding electrolyte additives to suppress the electrolyte decomposition [ 14 , 41 , 42 ]. Every method has some effect in improving LiCoPO 4 cathode performance.…”

Novel Co3(1–x)Fe3xV2O8 Nanoparticles as Highly Active and Noble-Metal-Free Electrocatalysts for Oxygen Evolution Reaction

“…The original electronic structures of the catalysts may be changed by metal doping so as to produce better catalytic properties. − In this perspective, the Fe-doping can improve the OER activity dramatically . Qiu et al reported that the Fe-CoOOH/G nanohybrids acted as a catalyst for OER.…”

Improvement of the EC Performance in LCP-MOF Electrode Materials by Succinic Anhydrate Addition to the Electrolyte

“…One of the most promising olivine structures is LiCoPO 4 (LCP) as a cathode material due to its high redox potential of around 4.8 V, its high energy density, and its theoretical capacity of ~167 mAhg −1 [1][2][3]. Nevertheless, it undergoes a low electrochemical performance for many reasons, such as its low lithium-ion and electronic conductivity and its high voltage effect on the lifetime of the electrolyte (stability) [4,5].…”