High-voltage and high-safety nickel-rich layered cathode enabled by a self-reconstructive cathode/electrolyte interphase layer

Abstract

To achieve widespread adoption of Ni-rich layered oxides in commercial applications, it is highly necessary to address their cyclic stabilities and safety aspects under prolonged and harsh operating conditions, which will aggravate the simultaneous degradation of the Ni-rich cathode and electrolyte due to the more serious interfacial side reactions between them. Herein, a self-reconstructive cathode/electrolyte interphase (CEI) layer with good interfacial stability was designed and constructed for Ni-rich cathode, through the incorporation of dendritic mesoporous silica (DMS) with rich surface silicon-hydroxyl groups as a multifunctional electrolyte additive. The DMS shows the ability to reconstruct the CEI layer in real time, i.e., endowing the CEI layer with defluorination function, spontaneously formed LiPO2F2, and in-situ formed anti-fluorination protective layer with enhanced electron and Li+ diffusion. As expected, the sample with a self-reconstructive CEI layer exhibits significantly superior cyclic stability compared to the pristine one under extended cut-off voltage (4.5 V) or elevated temperature (55°C). Notably, the flame-retardant effect of DMS additive can also contribute towards the thermal stability of the electrolyte and electrode, which will effectively improve the safety aspect of the battery. Thus, this work provides new insights into reducing undesired self-reinforced failure process in Ni-rich cathode and reconstructing a self-healing CEI layer for high-safety, high-voltage lithium-ion batteries.