Ultrafast Ion Transport via Dielectric Nanocube Interface

Abstract

Drastic enhancement in the high‐rate capability of lithium‐ion batteries to the level of supercapacitors while maintaining high energy density is required for next‐generation power sources. Incorporating dielectric BaTiO3 (BTO)‐based nanocubes (NCs) into the active materials–electrolyte interface provides an ultrafast charge transfer pathway via the dielectric layer. The highly dispersed NC‐decorated LiCoO2 (LCO) treated at the optimized temperature of 600 °C displays significantly enhanced high‐rate capability; the cell maintains 56.7 mAh g‐1 at 50C (1C = 160 mA g‐1), which compares with null capacity at the same rate for bare LCO. Comparing the NCs with conventional sol‐gel‐derived nanoparticles, the capacity retention at 10C (vs 0.1C) steadily increases with increasing active materials–dielectric–electrolyte triple‐phase interface (TPI) in the NC‐decorated case, whereas the capacity retention decreases markedly at similar TPI density in the sol‐gel case. In the sol‐gel case, the amount of Li ions accumulating at the TPI greatly exceeds the maximum amount of Li ions involved in electron exchange through the redox reaction within the charge/discharge time. In the NC case, most Li ions at the TPI participate effectively in the redox reaction, which results in fast charge transfer since the TPI sites are abundantly supplied with Li ions.

Enhanced Charge Accumulation in Activated Carbon via the Dielectric Interface

“…TPI density is the key structural factor determining charge accumulation in the dielectric-modified AC. Increased TPI density substantially improves the high rate capability of conventional LIBs. − Here, we investigated the relationships between TPI density and the resulting electric capacities for the BT-AC system. BTs with mean particle sizes of 30, 50, and 100 nm were used for the measurements.…”

“…d EDL depends on the desolvated Li concentration; thus, increased naked Li + ion density yields a thinner EDL and greater cell capacitance. − Additionally, solvated Li + ions exhibit infrequent diffusion into AC micropores because the solvated ion size is comparably larger than the pore diameter. − Accordingly, it is important to enhance the desolvation activities of carrier ions to strengthen the capacities of AC-based electrodes. In conventional LIBs, the high rate characteristics of LiCoO 2 (LCO) were substantially improved by the incorporation of a BaTiO 3 (BT)-based dielectric layer as an artificial solid electrolyte interface. − Indeed, when an ethylene carbonate (EC)-based electrolyte is used, the activated desolvation of Li + from (EC) 4 molecular coordinates delivers more rapid charge transport at the LCO–electrolyte interface, resulting in significant enhancement of the high rate capabilities of the LCO . Here, we demonstrate a novel charge-transfer architecture enabling the accumulation of activated ions into AC micropores via the dielectric layer.…”

Functional dielectric materials for high-performance solid-state batteries

“…The results showed that as TPI density increases, NC-LCO exhibits significantly enhanced high-rate performance, maintaining 56.7 mA h g À1 at 50C. 93 In conclusion, the significant improvement in rate performance can be attributed to TPI. Most of the Li + at TPI effectively participates in redox reactions, accelerating the rapid transfer of Li + .…”