Approaching high-performance pouch cell via fast thermal dissipation and polarization-assisted ion migration

To achieve higher holistic capability for lithium batteries via the simplest possible way is one of the most urgent issues for their industrialization. Here, a low-cost TiN (1 wt%) with excellent electrical/thermal conductivity and high permittivity was mixed into the positive electrodes of LiNi_0.5Co_0.2Mn_0.3O₂(NCM523)‖graphite pouch cells, delivering dramatically improved lithium battery performance, particularly in terms of cyclic stability, energy density, and thermal safety. The NCM523/TiN‖graphite cell delivered a capacity retention of 91.8% at 3C rate after 500 cycles (cf., only 85.0% before adding TiN). Importantly, the energy density for the pouch cell with TiN added was boosted by 15% at 5C. It is found that a small amount of TiN (1 wt%) not only facilitates electron transfer but also promotes faster heat-dissipation in the electrode during the charge/discharge process, beneficial for achieving fast Li-ion diffusion kinetics, balanced CEI/SEI-film evolution, and excellent cycling stability especially at high rates. High localized dielectric polarization induced by TiN enhances the Li-ions kinetics around the triple-phase interface of NCM523, TiN and electrolyte. This very convenient approach is highly feasible for producing much better and safer LIBs with little extra cost involved, which is key to industrialization.