Effect of polyvinyl pyrrolidone/sodium polyacrylate compound surfactants on slurry properties of lithium iron phosphate and electrochemical performance of the battery

The addition of surfactants is considered to be the most effective way to address agglomeration and instability in lithium battery slurry. Herein, polyvinyl pyrrolidone (PVP) and sodium polyacrylate (PAAS) compound surfactants are used as dispersants in lithium iron phosphate slurry. This compounding system not only solves the problem of reduced electrode peel strength caused by PAAS but also creates a synergistic effect through steric hindrance and electrostatic repulsion. The surface of the electrode prepared with the compound surfactants is smooth and firm. The electrodes prepared with 0.3 wt% PVP/0.2 wt% PAAS compound surfactant have the best electrochemical performance, and the results were obtained through excellent rate performance (475 mAh at 10 C) and excellent cycling performance (495.5 mAh with the capacity retention of 93.4% at 1 C after 300 cycles) compared with other samples. The addition of compound surfactants effectively eliminates the agglomeration of electrode surface, reduces the interfacial resistance, improves the electron mobility, and improves the battery rate performance. Meanwhile, the tight connection between the primary particles of lithium iron phosphate ensures efficient release and embedding of lithium ions.