Ferroelectric polarization accelerates lithium-ion diffusion for dendrite-free and highly-practical lithium-metal batteries

Abstract

Owing to the high specific capacity and lowest negative electrochemical potential, lithium metal as assembled with cathode materials such as sulfur, oxygen and so forth is regarded as a promising candidate for next-generation energy storage. However, the uncontrollable deposition of lithium ions (Li-ions) on anode surface tends to cause a disastrous surface passivation or soft short of battery during the long-term operation. One effective way to tackle this problem is controlling the nucleation and growth of lithium deposition by avoiding the formation of Li-ions barren areas near the electrode. In this work, a ferroelectric decoration layer of BiFeO3 (BFO) nanoparticles with low energy barrier for Li-ion diffusion on commercial separator is applied to construct polarization field to accelerate the Li-ion migratory, which can effectively eliminate the barren areas of Li-ions near the surface of anode. The strong interfacial polarization between the BFO and Li-ions leads to a dense and smooth nucleation of lithium deposition, resulting in a long-term stability of lithium plating/stripping even at a low temperature of −10 °C in which the cells with BFO separator could deliver high Coulombic efficiency (CE) of 95 % at the current density of 0.5 mA cm−2 for 180cycles. Moreover, with high sulfur loading of 1000 mg/pouch cell, the Li–S pouch cell with BFO/PP separator could deliver specific capacity as high as 1408 mA h g−1 with 0.14% capacity decay per cycle even over 150 cycles. Our study demonstrates that BFO/PP separator can serve as the Li-ion booster to facilitate uniform lithium deposition to build highly-practical Li metal batteries.