Pre‑Agglomeration Granulation for Fluidized Bed Sintering of Geldart Group C LiFePO₄ With Enhanced Electrochemical...

Traditional static sintering of LiFePO₄ (LFP) in roller kilns suffers from low heat/mass transfer efficiency and uneven atmosphere distribution, leading to high energy consumption and inhomogeneous carbon coating. Fluidized-bed sintering offers superior transfer kinetics, yet battery-grade LFP belongs to Geldart Group C and is inherently non-fluidizable. Herein, a pre-agglomeration granulation strategy using glucose/poly(ethylene glycol) binders via spray drying successfully transforms LFP from Group C to Group A. Systematic comparison with static tube-furnace sintering reveals that dynamic fluidized-bed sintering promotes uniform Al³⁺ doping, suppresses abnormal grain growth, and enables the formation of a uniform, continuous carbon layer (∼ 9 nm). Benefiting from these structural improvements, the sintered LFP exhibits a more uniform grain size distribution and a well‑integrated carbon coating. Electrochemical evaluation reveals a capacity retention of 77% at 5C and 94% after 400 cycles. The material achieves an ion diffusion coefficient of 9.66×10^-13 cm² s^-1. This work not only overcomes the fluidization barrier of LFP, enabling kinetic optimization, structural control, and performance enhancement, but also establishes a general route to convert non-fluidizable Geldart C powders into fluidizable granules. The scalable and efficient fluidized-bed process paves the way for green, continuous manufacturing of high-performance LFP and other fine battery materials.