The Preparation and Electrochemical Performance of Olivine Cathode Materials Based on LiMn_1/3Fe_1/3Co_1/3PO₄/C

Abstract

Solid solution LiMn₁/₃Fe₃Co₁/₃₃PO₄/C ternary materials were prepared by sol-gel method with glycine or citric acid as chelating agents. SEM images indicate that the particles are well distributed with regular morphologies, and the particle sizes are around 300 nm for both samples. The cyclic voltammetry (CV) and charge-discharge curves show that the reversibility of Mn²+/Mn3+ couple is improved apparently. The redox potential corresponding to Fe²⁺/Fe³⁺ couple has been increased which is beneficial to the energy density, and the redox potential related to Co²⁺/Co³⁺ couple has been declined which could accelerate dynamics of intercalation/deintercalation and make the electrochemical reaction more smoothly. The obtained LiMn₁/₃Fe₁/₃Co₁/₃3PO₄/C materials with glycine as chelating agent deliver a capacity of 151.5, 142.6, 122.8, 97.9 mAh g⁻¹ at 0.05 °C, 0.1 C, 0.5 C and 1 C, respectively. And the obtained material with citric acid as chelating agent delivers a capacity of 150.8, 135.0, 111.5, 85.2 mAh g⁻¹, respectively, at the same rates.

Solvothermal synthesis of LiFe1/3Mn1/3Co1/3PO4 solid solution as lithium storage cathode materials

“…A large discharge capacity of 120 mA h g À1 is still achieved even at 5C rate, as far as we know, which is the best result at such a high rate in recent literature. [28][29][30][31][32][33][34][35] The outstanding rate capability can be mainly attributed to the following two factors. Firstly, the nanometer dimension of LFMCP/C particles shortens the solid diffusion pathway of the Li ions.…”

“…Wu et al 32 synthesized LiCo 1/3 Fe 2/3 PO 4 /C cathode material using CoFe 2 O 4 as raw material, showing a discharge capacity of 152.9 mA h g À1 at 0.1C. Xiong et al 33 prepared LiMn 1/3 Fe 1/3 Co 1/3 PO 4 /C composite through a sol-gel technique, which exhibited a reversible capacity of 142.6 mA h g À1 at 0.1C. The in situ XRD analysis illustrated that LiCo 1/3 Mn 1/3 Fe 1/3 PO 4 retains the stable olivine structure during the charge/discharge between 2.0 and 5.0 V because the metal antibonding state can be stabilized by the strong P-O covalent bonds.…”

Phosphate Polyanion Materials as High-Voltage Lithium-Ion Battery Cathode: A Review

“…Furthermore, graphene and CNTs also played as carbon additives to improve the electrochemical performance, which results in an excellent rate profile and long-term stability with capacity retention of 85.2% for 500 cycles at 1 C-rate (Figure B). The sol–gel method had also been employed for 5 V vs Li/Li + carbon-coated LiMn 1/3 Fe 1/3 Co 1/3 PO 4 /C ternary solid solution composite cathode material preparation using glycine and citric acid as chelating agents, which exhibited high discharge capacity with serious capacity fading due to unstable crystal structures due to the Jahn–Teller distortion of Mn 3+ ions and electrolyte decomposition due to high-voltage operation. , …”

“…The sol−gel method had also been employed for 5 V vs Li/Li + carboncoated LiMn 1/3 Fe 1/3 Co 1/3 PO 4 /C ternary solid solution composite cathode material preparation using glycine and citric acid as chelating agents, which exhibited high discharge capacity with serious capacity fading due to unstable crystal structures due to the Jahn−Teller distortion of Mn 3+ ions and electrolyte decomposition due to high-voltage operation. 180,181 5.3. Hydrothermal and Solvothermal Synthesis.…”