Low-temperature piezoelectric/ferroelectric coating layer driving lithium-ion rapid diffusion and structure stability of LiCoO2 cathode

The increase in charging cut-off voltage accelerates the structure degradation and stress-strain accumulation of LiCoO2 (LCO) cathode, leading to heightened side reactions on the electrode surface and ultimately diminishing its electrochemical performance. Here, the piezoelectric LiTaO3 (LTO) and ferroelectric SrTiO3 (STO), and MgTiO3 (MTO) show matched preparation temperature with LCO electrode, which were utilized as coating layers to transform the stress and strain experienced during the high-voltage charging and discharging processes into polarization fields, thereby enhancing the electrochemical functionality. Taking the LTO coating layer as an example, the 2 wt% LTO-LCO electrode exhibits an obvious elevation of electrochemical, achieving 172.8 mAh center dot g-1 at 0.1 C (135.8 mAh center dot g-1 at 5 C) and maintaining a capacity retention rate of 84.8 % (1 C = 274 mAh center dot g-1 , 3.0-4.5 V) after 200 cycles. This research proves that the low-temperature piezoelectric/ferroelectric materials can be used as a coating layer of LCO electrodes to transform the stress and strain into polarization fields, which reduce the lattice expansion and accelerate the Li+ transport for designing high-performance LCO batteries in the future.