Surface Engineering Stabilizes Rhombohedral Sodium Manganese Hexacyanoferrates for High‐Energy Na‐Ion Batteries

Abstract

The rhombohedral sodium manganese hexacyanoferrate (MnHCF) only containing cheap Fe and Mn metals was regarded as a scalable, low‐cost, and high‐energy cathode material for Na‐ion batteries. However, the unexpected Jahn‐teller effect and significant phase transformation would cause Mn dissolution and anisotropic volume change, thus leading to capacity loss and structural instability. Here we report a simple room‐temperature route to construct a magical CoxB skin on the surface of MnHCF. Benefited from the complete coverage and the buffer effect of CoxB layer, the modified MnHCF cathode exhibits suppressed Mn dissolution and reduced intergranular cracks inside particles, thereby demonstrating thousands‐cycle level cycling lifespan. By comparing two key parameters in the real energy world, i.e., cost per kilowatt‐hours and cost per cycle‐life, our developed CoxB coated MnHCF cathode demonstrates more competitive application potential than the benchmarking LiFePO4 for Li‐ion batteries.

Three-Dimensional (3D) Ordered Macroporous Bimetallic (Mn,Fe) Selenide/Carbon Composite with Heterojunction Interface for High-Performance Sodium Ion Batteries

“…As can be seen in Figure S6 in the Supporting Information, the solid manganese-based Prussian analogue with smooth surfaces and solid structure was prepared through the conventional coprecipitation method. 51,52 After selenization treatment, the as-obtained 3DOM-MnFeSe x @C composite exhibits a regular tetrakaidecahedron morphology with particle sizes ranging from 1.0 μm to 1.5 μm, as illustrated in Figures 3a and 3b. Interconnected ordered macropores distributed on the surface and interior reveal that the 3DOM-MnFeSe x @C composite well inherits and preserves the morphology and macropore structure of the precursor.…”

“…As displayed in Figure S5 in the Supporting Information, SEM, TEM, SAED, and HRTEM images in the [100] direction is the same as those of 3DOM-Mn-PBA-2, except that its macroscopic particles are larger and the diameter of the internally distributed macropores is ∼190 nm. As can be seen in Figure S6 in the Supporting Information, the solid manganese-based Prussian analogue with smooth surfaces and solid structure was prepared through the conventional coprecipitation method. , …”

Polyanionic Cathode Materials for Practical Na-Ion Batteries toward High Energy Density and Long Cycle Life

“…To date, Prussian blue analogues (PBAs), the layered metal oxides (TMOs), and polyanionic compounds have the most commercial prospects among the various exploited cathode materials for NIBs. , PBAs attain wide attention and research interest due to their high theoretical capacity, 3D open crystal structure, and low cost of raw materials (e.g., Fe and Mn based Prussian blue analogues) . However, the fast precipitation kinetics for synthesis of PBA cathodes usually leads to the generation of considerable coordination water and lattice vacancies, which finally deteriorate the electrochemical performance.…”

TheKspgap enabled precipitation transformation reactions from transition metal hydroxides to sulfides for alkali metal ion storage

“…[2][3][4] Precipitation and coprecipitation methods, which are based on the K sp theory, are widely applied for material preparation or ionic removal in fields of energy, environment, health, catalysis, sensing, and so on. [5][6][7][8][9][10] Furthermore, the K sp gap between two ionic compounds sharing the same cation or anion can trigger precipitation transformation reactions, which widely exist in nature and daily life. For instance, the deeper ores of sphalerite (ZnS, K sp = 1.6 × 10 −24 ) and galena (PbS, K sp = 8.0 × 10 −28 ) can be converted to covellite (CuS, K sp = 6.3 × 10 −36 ) after being infiltrated by CuSO 4 solution, which are formed by the oxidation and eluviation of the shallower primary copper sulfide ore.…”