Low vacancy Fe-substituted Mn-based Prussian blue analogue
A system and method implementing and manufacturing transition metal cyanide coordination compounds (TMCCC) comprising Na, Fe, Mn, C, H, N, S, and O, wherein the TMCCC have 0-14% hexacyanometallate vacancies such as for application in electrochemical cells, including sodium ion secondary batteries.
1. An electrochemical device, comprising:
an electrically-conductive structure including a TMCCC represented by Formula II:
Na b1 K b2 Rb b3 Cs b4 Fr b5 Ti a1 V a2 Cr a3 Mn a4 Fe a5 Co a6 Ni a7 Cu a8 Zn a9 Ca a10 Mg a11 [R(CN) 6 ] c vac r (H 2 O) n (SO 4 ) j Formula II; wherein R(CN) 6 is a coordination complex selected from the group consisting of hexacyanoferrate, hexacyanocobaltate, hexacyanochromate, and hexacyanomanganate;
wherein vac identifies an R(CN) 6 vacancy;
wherein for at least one element of a set of alkali metal parameters {b1, b2}, {b1, b2}>0;
wherein for each element of the set {b1, b2, b3, b4, b5} excluding non-zero elements of said set of alkali metal parameters, 0≤{b1, b2, b3, b4, b5};
wherein for each element of the set {b1, b2, b3, b4, b5}, {b1, b2, b3, b4, b5}≤2;
wherein b1+b2+b3+b4+b5≤2;
wherein for each element of the set {a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11}, 0≤{a1, a2, a3, a4, a6, a7, a8, a9, a10, a11}≤1, a5>0;
wherein at least two of {a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11} are >0;
wherein 0<c≤1;
wherein 0≤r≤0.25;
wherein j>0;
wherein c+r=1; and
wherein n≥0.
2. The electrochemical device of claim 1 wherein said electrically-conductive structure includes a TMCCC positive electrode and further comprising a negative electrode.
3. The electrochemical device of claim 1 wherein Fe a5 includes Fe(II) d1 and Fe(III) d2 , wherein d1+d2=a5, wherein 0≤d1≤1; and wherein 0≤d2≤1.
4. The TMCCC of claim 1 wherein the TMCCC includes a specific capacity between 70-172 mAh/g.