KTiOPO4-structured electrode materials for metal-ion batteries: A review

A vanadium-based oxide-phosphate-pyrophosphate framework as a 4 V electrode material for K-ion batteries

“…7 Therefore, the focus is on polyanionic compounds which adopt open framework structures containing large channels and facilitate diffusion of large K + ions. [17][18][19] High energy density and long cycle life have been demonstrated in materials such as, KTiOPO 4 -type KVOPO 4 , 20 KVPO 4 F, [20][21][22] KFeSO 4 F, 23 and KTiPO 4 F, 24 layered VOPO 4 25 and KVPO 4 F, 26 [29][30][31][32][33][34][35] . Additionally, the redox potentials of the transition metals in the polyanionic frameworks are enhanced by the inductive effect of the strongly electronegative ligands.…”

Enhanced Electrochemical Properties of KTiOPO4–rGO Negative Electrode for Sodium and Potassium Ion Batteries

“…5 O 2 , P2-K 2 / 3 [ N i 2 / 3 T e 1 / 3 ] O 2 , P3-K 0.67 Ni 0.17 Co 0.17 Mn 0.66 O 2 ), Prussian blue analogues 6−8 (K 1.6 Mn[Fe(CN) 6 ] 0.96 •0.27H 2 O, K 1.89 Mn[Fe(CN) 6 ] 0.92 , KFe-[Fe(CN) 6 ]), and polyanionic compounds (KVPO 4 F, KVOPO 4 , 9 KFeSO 4 F, 10 and Na 3 V 2 O 2x (PO 4 ) 2 F 3−2x 11 ) have been reported as positive electrode materials for PIBs. 12 Among these positive electrode materials, KTiOPO 4 (KTP) structural type compounds 13 (i.e., KTiOPO 4 , KVPO 4 F, KVOPO 4 , KFeSO 4 F, and KTiPO 4 F) with the general formula AMXO 4 L [A = Li, Na, K; M = Fe, Ti, V; X = P, S, Si; L= O, F, OH] are more worthy as both positive and negative electrode materials for PIBs due to their high ionic conductivities and stable tunnel frameworks. 13 The structure of potassium titanyl phosphate (KTiOPO 4 ), which is the parent compound of this KTP-type structure family, is built by helical chains of the vertex-sharing TiO 6 octahedra running along the b-axis, which are corner-linked by the PO 4 tetrahedra to form a rigid three-dimensional (3D) framework hosting K + ions in spacious cavities.…”

“…12 Among these positive electrode materials, KTiOPO 4 (KTP) structural type compounds 13 (i.e., KTiOPO 4 , KVPO 4 F, KVOPO 4 , KFeSO 4 F, and KTiPO 4 F) with the general formula AMXO 4 L [A = Li, Na, K; M = Fe, Ti, V; X = P, S, Si; L= O, F, OH] are more worthy as both positive and negative electrode materials for PIBs due to their high ionic conductivities and stable tunnel frameworks. 13 The structure of potassium titanyl phosphate (KTiOPO 4 ), which is the parent compound of this KTP-type structure family, is built by helical chains of the vertex-sharing TiO 6 octahedra running along the b-axis, which are corner-linked by the PO 4 tetrahedra to form a rigid three-dimensional (3D) framework hosting K + ions in spacious cavities. 14 The theoretical capacity based on the insertion of one K + per formula is 135 mAh g −1 .…”

“…To date, various layered transition metal oxides (K 0.41 CoO 2 , K 0.3 MnO 2 , P2-K 0.7 Fe 0.5 Mn 0.5 O 2 , P2-K 2/3 [Ni 2/3 Te 1/3 ]­O 2 , P3-K 0.67 Ni 0.17 Co 0.17 Mn 0.66 O 2 ), Prussian blue analogues − (K 1.6 Mn­[Fe­(CN) 6 ] 0.96 ·0.27H 2 O, K 1.89 Mn­[Fe­(CN) 6 ] 0.92 , KFe­[Fe­(CN) 6 ]), and polyanionic compounds (KVPO 4 F, KVOPO 4 , KFeSO 4 F, and Na 3 V 2 O 2 x (PO 4 ) 2 F 3–2 x ) have been reported as positive electrode materials for PIBs . Among these positive electrode materials, KTiOPO 4 (KTP) structural type compounds (i.e., KTiOPO 4 , KVPO 4 F, KVOPO 4 , KFeSO 4 F, and KTiPO 4 F) with the general formula AMXO 4 L [A = Li, Na, K; M = Fe, Ti, V; X = P, S, Si; L= O, F, OH] are more worthy as both positive and negative electrode materials for PIBs due to their high ionic conductivities and stable tunnel frameworks …”

Quantum magnetism of ferromagnetic spin dimers in $α$-KVOPO$_4$

“…The tetrahedral XO 4 groups connect the chains into a three-dimensional network, yet leaving large channels for the A + ions that remain sufficiently mobile, especially at elevated temperatures. This feature triggered interest in AVOXO 4 as potential battery materials [8][9][10], whereas concurrent magnetism studies have also led to very encouraging results.…”