Substituted transition metal phospho olivines LiMM′PO4 (M = Mn, M′ = Fe, Co, Mg): Optimisation routes for LiMnPO4

Fine Structure and Electrochemical Performance Investigations of Spherical LiMn0.6Fe0.4PO4/C Cathode Material Synthesized via a Spray-Drying Route at Various Calcination Temperatures

LiMnxFe1-xPO4/C is characterized by excellent multiplicative performance and high operating voltage, and as a type of cathode material, it has a high electronic conductivity and thus has received much attention. In this paper, carbon-coated LiMn0.6Fe0.4PO4/C was synthesized using glucose + PEG2000 as the carbon source by wet sanding and spray-drying. The experimental results show that the use of sanding and the spray-drying method can make the particle size distribution of LiMn0.6Fe0.4PO4/C powder more uniform. The initial discharge specific capacity of the LiMn0.6Fe0.4PO4/C battery was 144.3 mA h g-1, and after 100 cycles at 1 C current, the discharge specific capacity of the battery remained at 128.2 mA h g-1 with a cycling efficiency of 94.3%. At the same time, the oxidation states and coordination environments of the elements Fe and Mn were elucidated by X-ray absorption fine structure spectroscopy. And the ex-Fe-MS was tested under different charging and discharging conditions. The sample optimized by the orthogonal test has good cycle stability and multiplication performance.

Nano-/Microhierarchical-Structured LiMn0.85Fe0.15PO4 Cathode Material for Advanced Lithium Ion Battery

Nano/microhierarchical-structured LiMn_0.85Fe_0.15PO₄/C cathode materials were prepared by solvothermal synthesis combined with spray pyrolysis. XRD patterns and HRTEM images indicate that the LiMn_0.85Fe_0.15PO₄/C are well crystallized and no impurity is observed. The as-prepared LiMn_0.85Fe_0.15PO₄/C porous spheres (0.5-11 μm) are accumulated by primary nanoparticles (∼50 nm in width, 50-250 nm in length). Adopting sucrose as a carbon source, the cathode delivers a reversible discharge capacity of 171.2 mAh g^-1 at 0.1C, almost exactly its theoretical capacity (∼170 mAh g^-1). Moreover, the composite exhibits high cycle stability without apparent capacity fading after 100 cycles at rates of 0.1C and 1C. The outstanding electrochemical performances are partially due to Fe²⁺ substitution and carbon coating, which improve the electrical conductivity, and importantly, due to its nano-/microhierarchical structure where primary nanoparticles exhibit high electrochemical activity, abundant mesopores benefit electrolyte penetration and the hierarchical structure ensures cycling stability.

Influence of HDI as a cathode film-forming additive on the performance of LiFe0.2Mn0.8PO4/C cathode

Herein, we construct a polymer protective layer on LiFe_0.2Mn_0.8PO₄/C particles with hexamethylene diisocyanate via the onium ionization–polymerization reaction.