TY - JOUR
T1 - The Intriguing Nature of Fluorine Doping on Li2CuO2 and the Reasons behind the Inhibition of Oxygen Evolution
AU - Juarez-Yescas, Carlos
AU - Oliver-Tolentino, Miguel
AU - Ramos-Sánchez, Guadalupe
AU - Vera-Ramirez, Marco A.
AU - Olmedo-González, Jorge
AU - Ochoa-Calle, Alvaro
AU - Manzo-Robledo, Arturo
AU - González, Federico
AU - González, Ignacio
N1 - Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/3/23
Y1 - 2020/3/23
N2 - Oxygen evolution is a major contributor to the degradation of lithium metal oxide cathode materials during initial charging, leading to low initial capacities and poor cyclability. The introduction of different ions to modify the electrochemical behavior of these materials and combat oxygen evolution is commonplace; while the benefits of these modifications are evident, the nature of these modifications are not fully understood. Herein, a multiangle approach is utilized to elucidate the effects of fluorine doping on the evolution of oxygen in Li2CuO2. Through XRD, the presence of fluorine is confirmed in the synthesized samples via the detection of the contraction in the unit cell of Li2CuO2 in the a and c directions, and the results are verified through solid-state 19F NMR. As a result of F-doping, the electrochemical results suggest a modification of the bulk properties, showing an increased reversible capacity. Li2CuO2 only discharges 83 mAh g-1 on the 10th cycle, while the cuprate doped with 5.0 mol % fluorine achieved a discharge capacity of 133 mAh g-1. This improvement is attributed to the presence of F in the structure of Li2CuO2, as determined via in situ DEMS experiments. Lastly, ab initio calculations further support the hypothesis that fluorine doping changes the density of states close to the Fermi level, altering the bulk properties and the likelihood for oxygen evolution.
AB - Oxygen evolution is a major contributor to the degradation of lithium metal oxide cathode materials during initial charging, leading to low initial capacities and poor cyclability. The introduction of different ions to modify the electrochemical behavior of these materials and combat oxygen evolution is commonplace; while the benefits of these modifications are evident, the nature of these modifications are not fully understood. Herein, a multiangle approach is utilized to elucidate the effects of fluorine doping on the evolution of oxygen in Li2CuO2. Through XRD, the presence of fluorine is confirmed in the synthesized samples via the detection of the contraction in the unit cell of Li2CuO2 in the a and c directions, and the results are verified through solid-state 19F NMR. As a result of F-doping, the electrochemical results suggest a modification of the bulk properties, showing an increased reversible capacity. Li2CuO2 only discharges 83 mAh g-1 on the 10th cycle, while the cuprate doped with 5.0 mol % fluorine achieved a discharge capacity of 133 mAh g-1. This improvement is attributed to the presence of F in the structure of Li2CuO2, as determined via in situ DEMS experiments. Lastly, ab initio calculations further support the hypothesis that fluorine doping changes the density of states close to the Fermi level, altering the bulk properties and the likelihood for oxygen evolution.
KW - DEMS
KW - cathode
KW - cross-polarization NMR
KW - fluorine-doped material
KW - lithium ion batteries
KW - oxygen evolution
UR - http://www.scopus.com/inward/record.url?scp=85080143842&partnerID=8YFLogxK
U2 - 10.1021/acsaem.9b02429
DO - 10.1021/acsaem.9b02429
M3 - Artículo
SN - 2574-0962
VL - 3
SP - 2771
EP - 2780
JO - ACS Applied Energy Materials
JF - ACS Applied Energy Materials
IS - 3
ER -