Research Status and Application Prospects of LiMnPO_4 as A New Generation Cathode Material for Lithium-Ion Batteries

Olivine-structured lithium manganese phosphate (LiMnPO_4) has the following advantages: excellent thermal stability, low cost, high safety and environmental benignity. Importantly, the theoretical energy density of LiMnPO_4 is about 20% higher than that of commercialized LiFePO_4 due to its higher Li~+ intercalation potential of 4.1 V (vs. Li~+/Li). Moreover, the high operating voltage of LiMnPO_4 is compatible with present non-aqueous organic electrolytes of lithium-ion batteries. Therefore, LiMnPO_4 is considered as a next generation cathode material for lithium-ion batteries. However, LiMnPO_4 suffers from poor electronic conductivity and low lithium diffusivity, resulting in its low discharge capacity and poor rate capability. And these intrinsic disadvantages hinder LiMnPO_4 from its practical applications in lithium-ion batteries. In this paper, recent researches in the modifications includi ng carbon coating, ion doping, nanoization and cyrstalline morphological controlling, full cells, patent situation and commercial progress are reviewed. The prospects of its future development are also predicted. Particularly, the experimental data by Advanced Li-ion Battery Engineering Lab fully proves that LiMnPO_4 has the feasibility of applying in lithium batteries ofHEVs or EVs. LiMnPO_4 composite such as LiMnPO_4/ternary cathode materials could be most likely to be realized in the near future

Constructing durable carbon layer on LiMn0.8Fe0.2PO4 with superior long-term cycling performance for lithium-ion battery

LiMn0.8Fe0.2PO4 is becoming one of the most promising cathode materials for lithium ion batteries. However, the capacity suffers from a loss during long-term cycling, which is directly associated with Mn dissolution due to the disproportionation reaction of Mn3+. Here, we report a chemical vapor deposition (CVD) approach to modify LiMn0.8Fe0.2PO4 particles with carbon so as to minimize Mn dissolution from cathode. The deposited carbon layer not only protects LiMn0.8Fe0.2PO4 cathode from electrolyte corrosion, but also enhances the electronic/ionic conductivity owing to its higher graphitize degree. As a consequence, the electrochemical performances have a significant improvement. The capacity retention achieves 96% after 450 cycles at 1 C at room temperature (25 degrees C). Even at elevated temperature (55 degrees C), the capacity retention also reaches at 97 % after 50 cycles at 1 C rate, which is much higher than that of untreated sample (89%). Hence, the cathode material based on LiMn0.8Fe0.2PO4 encapsulated with durable carbon by CVD method represents a promising strategy for developing its long-term cycling performance through suppressing Manganese dissolution. (C) 2016 Elsevier Ltd. All rights reserved

Concentration-gradient LiMn0.8Fe0.2PO4 cathode material for high performance lithium ion battery

It is a great challenge to combine good cycling performance with high rate capability for LiMn1-xMxPO4 cathode materials owing to the Mn dissolution upon cycling and its low electronic/ionic conductivity. Here, we report a novel concentration-gradient structure of LiMn0.8Fe0.2PO4 material constructed by solvothermal treatment. This material shows a linear increase of Mn concentration from the edge to the particle centre, but the inverse trend for Fe concentration, which leads to the formation of Mn-rich phase in bulk and Fe-rich phase at surface. The Fe-rich phase effectively suppresses the corrosion from the electrolyte that minimizes the Mn dissolution and also improves the electronic/ionic conductivity of the surface that decreases the cathode/electrolyte interface resistance. Consequently, this concentration-gradient material achieves superior capacity retention with 98% after 50 cycles at 1 degrees C even at elevated temperature, and also exhibits an excellent rate capability with the reversible capacity of 130 mA h g(-1) at 5 degrees C rate. These results suggest that the concentration-gradient LiMn0.8Fe0.2PO4 is an ideal type of cathode material for high performance Lithium ion batteries. (C) 2015 Elsevier B.V. All rights reserved

Effects of Ti additive on the structure and electrochemical performance of LiMnPO4 cathode material

The (1-x)LiMnPO4 center dot LixTix(PO4)(delta) (x=0, 0.01, 0.05, 0.10, 0.15, 0.20) cathode materials are successfully synthesized through a solid-state method. The structures and electrochemical properties of the prepared samples have been characterized comprehensively. It is found minority phases containing LiTi2(PO4)(3) and TiP2O7 were formed. The addition of Ti has obviously reduced the size of grains. Electrochemical tests indicate that the discharge capacities of LiMnPO4 samples can be significantly improved with the addition of Ti. Especially, the (1-x)LiMnPO4 center dot LixTi(PO4)(delta) sample with x=0.1 has the largest discharge specific capacity, which is more than 131 mAh g(-1) at 0.05 C. And EIS tests' demonstrate that the 0.9LiMnPO(4)center dot Li0.1Ti0.1(PO4)(delta) sample has lower charge transfer resistance and higher diffusion coefficient than the pristine LiMnPO4 sample. (C) 2014 Elsevier Ltd. All rights reserved