Electrochemical Properties of Li3Fe0.2Mn0.8CO3PO4 as a Li-Ion Battery Cathode

Abstract

Previously conducted high-throughput ab initio calculations have identified carbonophosphates as a new class of polyanion cathode materials. Li3MnCO3PO4 is the most promising candidate due to its high theoretical capacity and ideal voltage range. However, a major limitation of this material is its poor cyclability and experimentally observed capacity. In this work we synthesize Li3Fe0.2Mn0.8CO3PO4 to combine the high theoretical capacity of Li3MnCO3PO4 with the high cyclability of Li3FeCO3PO4. Li3Fe0.2Mn0.8CO3PO4 outperforms Li3MnCO3PO4 in cyclability, and shows little capacity fade over 25 cycles. The observed reversible capacity of 105 mAh/g is slightly greater than in Li3FeCO3PO4, and occurs at a higher average voltage.