LiFePO<sub>4</sub>-coated LiNi<sub>0.6</sub>Co<sub>0.2</sub>Mn<sub>0.2</sub>O<sub>2</sub> for lithium-ion batteries with enhanced cycling performance at elevated temperatures and high voltages
Longzhen You, Jiantao Tang, Qiang Wu, Congcong Zhang, Da Liu, Tao Huang, Aishui Yu
Abstract
(LFP). Although having a lower capacity, LFP is a safe and long-cycle cathode material; it is more chemically and thermally stable than NCM622 when exposed to common electrolytes. The LFP-coated NCM622 (NCM@LFP) showed similar rate performance and cycling performance at room temperature compared with the pristine NCM622 under the same conditions. However, significant differences between the NCM622 and NCM@LFP began to emerge at high temperatures. During cycling at 1C for 100 cycles at 55 °C, NCM@LFP showed much improved specific discharge capacity retentions of 92.4%, 90.9%, and 88.2% in the voltage ranges of 3-4.3 V, 3-4.4 V and 3-4.5 V, respectively. The NCM622 suffered significant discharge specific capacity decay under the same condition. In addition, as demonstrated by the delayed exothermic peak in the differential scanning calorimetry (DSC) test, NCM@LFP exhibited excellent thermal stability compared with NCM622, which is critical to battery safety.