Enhanced kinetic behaviors of LiMn0.5Fe0.5PO4/C cathode material by Fe substitution and carbon coating

Abstract

The LiMn 0.5 Fe 0.5 PO 4 /C nanocrystallites with a uniform size (∼50 nm) are successfully prepared by employing a facile solvothermal method at 180°C. Amphiphilic carbonaceous material (ACM) is chosen as the carbon precursor and forms a homogeneous carbon layer covering the LiMn 0.5 Fe 0.5 PO 4 particles. The asprepared LiMn 0. 5 Fe 0. 5 PO 4 /C sample, with a high Brunauer-Emmett-Teller (BET) surface area of 69.3 m 2 g −1 , is used as the cathode material for lithiumion batteries (LIBs) and delivers a reversible capacity of 158 mAh g −1 at 0.05 C. It shows remarkable rate capability with discharge capacities of 130 mAh g −1 at 1 C, 105 mAh g − 1 at 10 C and 99 mAh g − 1 at 30 C. Meanwhile, the material maintains 121 mAh g −1 at 1 C after 150 cycles with 93 % capacity retention. The kinetic behaviors of LiMn 0.5 Fe 0.5 PO 4 /C sample are investigated by high throughout cyclic voltammetry. The small particle size, partial Fe substitution, and homogeneous carbon coating make a synergetic effect on enhancing the sample's electrochemical properties.

Olivine Positive Electrodes for Li-Ion Batteries: Status and Perspectives

“…However, as already mentioned in the previous section devoted to LMP, using nanoparticles has disadvantages in terms of handing, manufacturing, and volumetric density. To avoid them, hierarchical structures have been synthesized, such as LiMn 0.5 Fe 0.5 PO 4 spheres [178]. Microspheres made of carbon-coated nanocrystalline LiFe 0.6 Mn 0.4 PO 4 (~100 nm) [179] were synthesized by sintering spherical precursor powders prepared by a modified spray drying method with a double carbon coating process.…”

Recent Advances of Mn‐Rich LiFe1‐yMnyPO4 (0.5 ≤ y < 1.0) Cathode Materials for High Energy Density Lithium Ion Batteries

“…Encouraged by the above‐mentioned methods and combination of other novel strategies, such as optimization of experimental conditions (such as calcinations temperature and time, selection of precursors and carbon sources, and optimization of Fe/Mn ratio), special morphology design, cation/anion doping, and surface coating/compositing by other conductive agents or lithium ion conductor, investigation on the improvement of the electrochemical performances and thermal stability of LFMP‐based cathode materials has always been a hot spot in the very recent years. A number of Mn‐rich LiFe 1‐ y Mn y PO 4 /C (0.5 ≤ y < 1.0) cathode materials with high specific capacity, superior rate performance, and excellent cycle stability have also been reported …”

“…Typical novel approaches employed in fabricating LFMP‐based cathode materials attempted to improve the electrochemical performance of LiFe 1‐ y Mn y PO 4 are listed in Table 1 and also shown in Figure 13 . These synthesis methods mainly include solvothermal method, co‐precipitation method, high‐energy ball‐milling (HEBM)‐assisted solid state reaction, sol‐gel route, carbon gel‐combustion synthesis process, (microwave‐assisted) hydrothermal route and spray drying method . It is noted that annealing in inert atmospheres can enhance the electrochemical performances of LFMP‐based cathode materials obtained by most of the above‐mentioned methods, which suggests it is a necessary process to obtain LFMP‐based materials for practical application.…”

Mixed-carbon-coated LiMn0.4Fe0.6PO4 nanopowders with excellent high rate and low temperature performances for lithium-ion batteries

“…Simultaneously, carbon coating layer is also one of the principal factors to influence the electrochemical performance. Basically, the uniform carbon coating is hardly to be achieved from the simply mixed nano-LMFP with organic matters except for the high amount of the organics [21,26,[34][35][36][37][38][39][40], the residual high amount carbon after carbonization is electrochemical inert, which can reduce the specific capacity of active materials.…”