Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States.
Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States.
ACS Appl Mater Interfaces. 2023 Apr 19;15(15):19011-19020. doi: 10.1021/acsami.3c01515. Epub 2023 Apr 10.
Lithium iron phosphate (LiFePO, "LFP") was investigated as an additive in the cathode of lithium-sulfur (Li-S) batteries. LFP addition boosted the sulfur utilization during Li-S cycling, achieving an initial capacity of 1465 mAh/g and a long cycle life (>300 cycles). Polysulfide adsorption experiments showed that LFP attracted polysulfides, and thus, the presence of LFP should alleviate the shuttle effect, a common failure mode. Postmortem characterization found iron phosphides, iron phosphates, and LiF in the electrode, indicating that LFP underwent dynamic reconstruction during Li-S cycling. We suspect that the formation of these species played a role in the observed performance. From the processing standpoint, adding LFP improved slurry rheology, making the preparation of a high-loading electrode more consistent. Benefiting from the high sulfur utilization and the ability to prepare electrodes with high mass loading, the S-LFP hybrid cell showed an excellent areal capacity of 2.65 mAh/cm and could be stably cycled at 2 mAh/cm for 250 cycles. Our results demonstrated the LFP addition as a promising strategy for realizing Li-S batteries with high sulfur loading and areal capacity.
磷酸铁锂（LiFePO，"LFP"）被研究作为锂硫（Li-S）电池阴极的添加剂。LFP 的添加提高了 Li-S 循环过程中硫的利用率，实现了初始容量为 1465 mAh/g 和长循环寿命（>300 次循环）。多硫化物吸附实验表明，LFP 吸附多硫化物，因此，LFP 的存在应该减轻常见的失效模式——穿梭效应。 电极的后处理表征发现了铁磷化物、铁磷酸盐和 LiF，表明 LFP 在 Li-S 循环过程中经历了动态重构。我们怀疑这些物质的形成在观察到的性能中发挥了作用。从加工的角度来看，添加 LFP 改善了浆料的流变性能，使得制备高载量电极更加一致。得益于高硫利用率和制备高载量电极的能力，S-LFP 混合电池表现出优异的面容量为 2.65 mAh/cm，并且可以在 2 mAh/cm 的电流密度下稳定循环 250 次。我们的结果表明，添加 LFP 是实现高硫载量和面容量的 Li-S 电池的一种很有前途的策略。
