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

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.