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-_y Mn _y PO₄, LMFP) as a cathode material for lithium-ion batteries has been severely hindered by challenges, such as two-phase stacking (LiFePO₄ and LiMnPO₄), inhomogeneous Mn/Fe distribution, and electrochemical performance degradation. This study proposes a precursor homogenization strategy based on manganese iron pyrophosphate [(Fe_1-_y Mn _y )₂P₂O₇, MFP]solid solutions. By designing and developing an atomization high-temperature synthesis (AHTS) roaster, we achieved continuous production of MFP, enabling the preparation of high-performance LMFP cathode materials. The MFP precursor employs atomic-scale Fe/Mn coprecipitation to transfer uniformity to the LMFP lattice, suppressing anti-site defects and eliminating the coexistence of two-phase stacking, thereby overcoming the limitations of traditional modification methods such as carbon coating and doping). The AHTS-MFP process employs a micron-scale atomized droplet reactor and a multi-constraint coupled iterative optimization design method to create a specialized synthesis device. Three-dimensional coupled simulations integrating thermodynamics, fluid dynamics, and chemical reaction kinetics were used to optimize the flow field, temperature field, and oxygen concentration control, resulting in a stable "gas vortex lock" structure. This ensures that the atomized droplets sequentially undergo evaporation, coprecipitation, drying, and condensation reactions within the furnace, with a residence time exceeding 15 seconds, leading to high crystallinity and elemental homogeneity. Key innovations include symmetrical nozzle arrays, a tangential flue combustion system, a multilayer oxygen-blocking composite structure, and dynamic nitrogen injection technology to precisely control the oxygen concentration in the roaster below 1%. The production-test samples of (Fe_0.35Mn_0.65)₂P₂O₇were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), HAADF-STEM and energy-dispersive spectroscopy (EDS) mapping, confirming that the samples are solid solution materials with uniform elemental distribution. The resulting LMFP cathode material, LiFe_0.35Mn_0.65PO₄, exhibited 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. Moreover, this study addresses the challenges of two-phase stacking and uneven elemental distribution in LMFP industrialization through process and equipment innovation, providing key technical support for its industrial production.

Key words: manganese iron pyrophosphate, lithium manganese iron phosphate, atomization high-temperature synthesis, solid solution

CLC Number:

TK 02

Kai TANG. Design of a continuous production facility for solid solution manganese iron pyrophosphate[J]. Energy Storage Science and Technology, 2025, 14(11): 4098-4111.

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	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