3D Printing Integrated Lipophilic Additives Engineering to Enhance Wettability of Thick Electrodes Achieving High Rate and High Areal Capacity.

The poor diffusion and transfer kinetics of Li is the critical bottleneck for energy and power density in thick electrodes. Here, we develop a 3D-printed magnesium silicate for solid-state integrated lipophilic additive engineering technology to fabricate thick electrodes, effectively mitigating concentration polarization caused by the Li gradient distribution. By grafting cetyltrimethylammonium, a cationic surfactant-modified inorganic filler (LCN) is prepared, which is added into the LiFePO (LFP) slurry for 3D printing into a porous 810 μm thick LFP cathode. The introduced alkyl-lipophilic groups endow the cathode with higher adsorption energy, shortening the wetting time of the electrolyte by 75%. Moreover, the alkylammonium electron-donating groups not only increase the electron cloud density around O within the electrode but also decrease the crystallinity of the binder, enhancing the Li transfer and transport kinetics. Furthermore, the 3D network porous structure improves the ionic and electronic conductivity, resulting in a substantial enhancement in rate capability. Even at high current densities of 2 and 5 mA cm, the 3D-printed LFP cells with LCN deliver the areal capacities of 8.75 and 3.50 mAh cm, respectively. And after 100 cycles at 0.3 mA cm, it remains at a high capacity of 6.98 mAh cm, breaking the limitation of ion transport in thick electrodes. This work provides a strategy in addressing the wettability challenges of thick electrodes, opening another way for the development of high-energy/power-density energy storage systems.