Design of a Continuous Production Facility for Solid-Solution Manganese Iron Pyrophosphate

doi:10.19799/j.cnki.2095-4239.2025.0493

Abstract

Abstract:

The commercialization of lithium manganese iron phosphate (LiFe_1-yMn_yPO₄, LMFP) as a cathode material for lithium-ion batteries has been severely hindered by challenges such as two-phase stacking (LiFePO₄ & LiMnPO₄), inhomogeneous Mn/Fe distribution, and electrochemical performance degradation. This study proposes a precursor homogenization strategy based on manganese iron pyrophosphate ((Fe_1-yMn_y)₂P₂O₇, MFP) solid solutions. By developing and designing an atomization high-temperature synthesis (AHTS) roaster, continuous production of MFP was achieved, enabling the preparation of high-performance LMFP cathode materials. The MFP precursor employs atomic-scale Fe/Mn co-precipitation to transfer uniformity to the LMFP lattice, suppressing anti-site defects and eliminating two-phase stacking coexistence, thereby overcoming the limitations of traditional modification methods (e.g., carbon coating, doping). The AHTS-MFP process utilizes a micron-scale atomized droplet reactor and a multi-constraint coupled iterative optimization design method to develop a specialized synthesis device. Through three-dimensional coupled thermodynamics-fluid dynamics-chemical reaction kinetics simulations, flow field, temperature field, and oxygen concentration control were optimized, forming a stable "gas vortex lock" structure. This ensures that atomized droplets undergo evaporation, co-precipitation, drying, and condensation reactions sequentially within the furnace, with a residence time exceeding 15 seconds, achieving high crystallinity and elemental homogeneity. Key designs include symmetrical nozzle arrays, a tangential flue combustion system, and a multi-layer oxygen-blocking composite structure, combined with dynamic nitrogen injection technology to precisely control the oxygen concentration in the roaster below 1%. The SEM images, XRD patterns, HAADF-STEM images, and EDS mapping results of the samples (Fe_0.35Mn_0.65)₂P₂O₇ prepared in the production test show that the samples are solid solution materials with uniform distribution of each element. The LMFP cathode material LiFe_0.35Mn_0.65PO₄ prepared from it exhibits a uniform olivine-type structure. The XRD pattern shows no secondary phases, and the HAADF-STEM images and EDS mapping results indicate that each element in the sample is uniformly distributed, confirming that the uniformity of the precursor is successfully transmitted to the final product. Through process and equipment innovation, this study has overcome the problems of two-phase stacking and uneven element distribution in LMFP industrialization, providing key technical support for its industrial production.

Key words: Manganese iron pyrophosphate (MFP), Lithium manganese iron phosphate (LMFP), Atomization high-temperature synthesis (AHTS), Solid solution

CLC Number:

TK02

Kai TANG. Design of a Continuous Production Facility for Solid-Solution Manganese Iron Pyrophosphate[J]. Energy Storage Science and Technology, doi: 10.19799/j.cnki.2095-4239.2025.0493.

Figures/Tables 10

Fig. 1

Table 1

Fig. 2

Table 2

Model Constants"

参数	近壁区（F₁=1）	自由剪切流（F₁=0）
$σ k$	0.85	1.0
$σ ω$	0.5	0.856
$β$	0.075	0.0828
$α$	5/9	0.44

Table 2

Fig. 3

Fig. 4

Fig. 5

Fig.6

Fig. 7

Fig. 8

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约束条件	关键参数	设计依据
1	固溶体，无杂相	产品目标要求
2	反应时长>15 s	雾化高温合成炉制备焦磷酸亚锰铁的工作原理
3	氧气浓度<1%	防止Fe²⁺、Mn²⁺离子被氧化
4 4 4 4	喷嘴附近300~450 ℃ 喷嘴往下400~500 ℃ 炉膛中部500~750 ℃ 炉壁附近750~850 ℃	雾化高温合成炉制备焦磷酸亚锰铁的工作原理雾化高温合成炉制备焦磷酸亚锰铁的工作原理雾化高温合成炉制备焦磷酸亚锰铁的工作原理雾化高温合成炉制备焦磷酸亚锰铁的工作原理