TY - JOUR
T1 - Calorimetric Study of Mixed Phosphates Na4M3(PO4)2P2O7 (M = Mn2+, Fe2+, Co2+, Ni2+) to Evaluate the Electrochemical Trends
AU - Jayanthi, K.
AU - Lochab, Shubham
AU - Barpanda, Prabeer
AU - Navrotsky, Alexandra
N1 - Publisher Copyright:
© 2023 American Chemical Society.
PY - 2023/6/22
Y1 - 2023/6/22
N2 - Mixed polyanionic compounds have been studied extensively as viable cathode materials for sodium-ion batteries. Mixed phosphates, Na4M3(PO4)2P2O7 (M = Mn2+, Fe2+, Co2+, Ni2+), provide a low barrier for Na-ion diffusion, being advantageous in comparison to phosphates and pyrophosphates. The reported order of sodium extraction is ambiguous and remains unclear. Despite being structurally similar, electrochemical performance differs for all four analogues with different degrees of (de)sodiation, according to the transition element present. Here, high-temperature oxide melt solution calorimetry has been used to establish the relation between thermodynamic phase stability and observed capacity for this series of mixed phosphates. Thermodynamic phase stability largely depends on the kind of structure, type of bonding, and size of the cations present. So, according to our results, the thermodynamic phase stability follows the order Na4Mn3(PO4)2P2O7 > Na4Fe3(PO4)2P2O7 > Na4Co3(PO4)2P2O7 > Na4Ni3(PO4)2P2O7. The thermodynamic studies serve as guidelines for the selection of compositions with the potential for fabricating advanced cathode materials with maximum performance.
AB - Mixed polyanionic compounds have been studied extensively as viable cathode materials for sodium-ion batteries. Mixed phosphates, Na4M3(PO4)2P2O7 (M = Mn2+, Fe2+, Co2+, Ni2+), provide a low barrier for Na-ion diffusion, being advantageous in comparison to phosphates and pyrophosphates. The reported order of sodium extraction is ambiguous and remains unclear. Despite being structurally similar, electrochemical performance differs for all four analogues with different degrees of (de)sodiation, according to the transition element present. Here, high-temperature oxide melt solution calorimetry has been used to establish the relation between thermodynamic phase stability and observed capacity for this series of mixed phosphates. Thermodynamic phase stability largely depends on the kind of structure, type of bonding, and size of the cations present. So, according to our results, the thermodynamic phase stability follows the order Na4Mn3(PO4)2P2O7 > Na4Fe3(PO4)2P2O7 > Na4Co3(PO4)2P2O7 > Na4Ni3(PO4)2P2O7. The thermodynamic studies serve as guidelines for the selection of compositions with the potential for fabricating advanced cathode materials with maximum performance.
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U2 - 10.1021/acs.jpcc.3c01975
DO - 10.1021/acs.jpcc.3c01975
M3 - Article
AN - SCOPUS:85163548744
SN - 1932-7447
VL - 127
SP - 11700
EP - 11706
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 24
ER -