Abstract:

The viscosity，solid content，and stability of lithium iron phosphate slurry are important parameters in the battery manufacturing process，which will directly affect the quality of the coated electrode plates and ultimately affect the performance and lifespan of the battery.A series of lithium iron phosphate materials（LFP/C） coated with different carbon sources were prepared using high-temperature solid-phase method，and their physical，electrochemical and processing properties were studied.The XRD results showed that the LFP/C samples prepared with three organic compounds as carbon sources all exhibited high crystallinity，and no obvious impurities were found.The Raman results showed that the carbon layer graphitization degree of LFP/C-3 sample coated with sucrose as the carbon source was the highest.The SEM and TEM results demonstrated that the LFP/C-3 sample had the smallest primary particle size and good particle dispersion，with a carbon layer thickness of about 5 nm and good coating uniformity.The electrochemical characterization results showed that the discharge specific capacity of LFP/C-3 sample reached 154.6 and 130.9 mA·h/g at 0.1C and 1.0C rate，respectively，and had excellent rate performance.After 110 cycles at 1.0C rate，the capacity retention rate was as high as 98.2%.However，the LFP/C-1 sample coated with glucose as the carbon source showed the best processing performance.Under the same solid content conditions，the initial slurry viscosity was 10 738 mPa·s.The three-stage thixotropy test results showed a viscosity recovery rate of 97.86%.The results provided some reference significance for the selection of carbon sources in the industrial production of lithium iron phosphate.

Key words: carbon sources, lithium iron phosphate, slurry, electrochemical performance, processing performance