Increased demand for lithium resources has led to increased Li costs and supply problems and increased the importance of lithium ion battery (LIB) recycling. In this study, lithium phosphate from LIB recycling wastewater was refined in a simple process using deionized water (DI). The morphologies and compositions associated with purifying Li3PO4 were investigated using X-ray diffraction, field emission-scanning electron microscopy, simultaneous thermogravimetric-differential thermal analysis, differential scanning calorimetry, pH measurement, inductively coupled plasma optical emission spectroscopy, and carbon and sulfur determinators. Simple refining with DI can increase Li3PO4 purity from 94.601% to 98.867%. LiFePO4 (LFP) was then synthesized using the purified Li3PO4; its morphology was studied and its electrochemical performance evaluated by constant current charge/discharge testing and cyclic voltammetry. The LFP cathode fabricated from purified Li3PO4 exhibited improved electrochemical properties, particularly in terms of initial capacity and cycling stability. (c) 2019 The Electrochemical Society.