Enhanced Cycle Performance and Thermal Safety of High Nickel Ternary Batteries Through TiO2/TiN Incorporation

In this study, a low-cost and simple ternary soft-pack cell with a high nickel content was developed. Specifically, nanoparticles of TiO2 and TiN were uniformly dispersed in the cathode slurry during the pulping process. TiO2 acts as a sacrificial protective agent at the interface, reacting with the HF produced in the electrolyte to reduce the dissolution of transition metals and to slow down the microcracks of positive particles during cycling. Meanwhile, the high thermal conductivity and conductivity of TiN, serving as an interfacial soaking agent, can improve the thermal safety of the battery and reduce the uneven temperature rise of the battery. Under the synergistic coupling of these two materials, TiO2 acts as a sacrificial agent to maintain the integrity of particles and avoid the fracture and spalling of main particles, while TiN disperses and homogenizes the thermal effect caused by the lithium ion intercalation process of a soft-pack full battery. Moreover, the interfacial CEI film at the positive phase boundary is stabilized, which not only enhances the cycle retention and electrochemical performance, but also leads to a significant improvement in cycle life. Therefore, the addition of TiO2/TiN greatly improves the cycle performance and thermal safety performance of high nickel ternary batteries at high rate and high temperature.