Vacancy and Composition Engineering of Manganese Hexacyanoferrate for Sodium-Ion Storage

Abstract

Manganese hexacyanoferrate (MnHCF) with an open framework is suitable for accommodating sodium ions. However, it suffers from severe capacity decay caused by the large structural deformation resulting from the Jahn−Teller (J−T) distortion of Mn−N 6 octahedra. By taking advantage of the strong chelation between EDTA and Mn ions, a strategy employing Mn vacancies (V Mn ) in combination with the introduction of Ni is proposed to suppress the J−T distortion of MnHCF. A Ni-doped MnHCF with V Mn and a low crystal water content (K 1.95 Na 0.05 Ni 0.02 Mn 0.93 [Fe(CN) 6 ] □ 0.05 •0.41H 2 O) is prepared, which delivered an improved capacity retention of 80% at 0.5C after 100 cycles. This work provides a combined vacancy and composition engineering strategy for effective suppression of J−T distortion in the MnHCF framework toward high-performance sodium-ion batteries.

Inhibiting the Jahn–Teller Effect of Manganese Hexacyanoferrate via Ni and Cu Codoping for Advanced Sodium‐Ion Batteries

“…[12] Furthermore, due to the large grain size, Mn-PBA is not fully activated, achieving a maximum specific capacity of 123 mAh g −1 at the second cycle (Figures S13b, S14, and S15, Supporting Information). [12,36] The rate performance of both samples is compared and shown in Figure 3c and Figure S16 (Supporting Information). MnCuNi-PBA exhibits higher reversible capacities at current densities of 0.01, 0.05, 0.1, 0.2, 0.3, 0.5, 0.8, 1.0, 1.5, and 2.0 A g −1 , with values of 113.1, 106.1, 102.8, 98.4, 95.7, 90.8, 85.2, 81.8, 73.8, and 66.2 mAh g −1 , respectively, which are substantially higher than those of the Mn-PBA.…”

Promising Cathode Materials for Sodium-Ion Batteries from Lab to Application

“…After that, He and coworkers reported that the phase structure of Mn-HCF would change from rhombohedral to cubic after Sn 4+ doping, and enhanced capacity retention after 100 cycles at 240 mA g –1 was obtained (80.5% vs 54.0% for bare Mn-HCF) . Lately, Jahn–Teller distortion was found by Shao’ group to be repressed through employing Mn vacancies (V Mn ) in combination with Ni doping …”

“…162 Lately, Jahn−Teller distortion was found by Shao' group to be repressed through employing Mn vacancies (V Mn ) in combination with Ni doping. 163 In order to further enhance the electrochemical performance, multication lattice substitution has been employed. 164,165 High quality (HQ)-Ni x Co 1−x [Fe(CN) 6 ] PBAs were synthesized through a chelating agent (trisodium citrate)/surfactant (polyvinylpyrrolidone, PVP) coassisted crystallization method with fewer [Fe(CN) 6 ] vacancies and water molecules in Han's group.…”

“… 162 Lately, Jahn–Teller distortion was found by Shao’ group to be repressed through employing Mn vacancies (V Mn ) in combination with Ni doping. 163 …”

Preparation of Low-Defect Manganese-Based Prussian Blue Cathode Materials with Cubic Structure for Sodium-Ion Batteries via Coprecipitation Method

“…According to the relevant literature, the differences in the electrochemical performances of these materials are mainly caused by two aspects: (1) A large number of Fe(CN) 6 vacancy defects. These defects will be occupied by some coordination water, leading to an increase in the lattice water content and blockage of Na + transport channels [21,[27][28][29][30]. At the same time, the presence of excessive defect sites and coordination water leads to the collapse of the cyanide connection framework during the cycling process, further affecting the storage performance of sodium ions.…”