Chen Yanjing, Nie Mengyun, Lucht Brett L, Saha Amitesh, Guduru Pradeep R, Bose Arijit
Department of Chemical Engineering ‡Department of Chemistry, University of Rhode Island , Kingston, Rhode Island 02881, United States.
ACS Appl Mater Interfaces. 2014 Apr 9;6(7):4678-83. doi: 10.1021/am404947z. Epub 2014 Mar 26.
Silicon (Si) is a promising candidate for lithium ion battery anodes because of its high theoretical capacity. However, the large volume changes during lithiation/delithiation cycles result in pulverization of Si, leading to rapid fading of capacity. Here, we report a simple fabrication technique that is designed to overcome many of the limitations that deter more widespread adoption of Si based anodes. We confine Si nanoparticles in the oil phase of an oil-in-water emulsion stabilized by carbon black (CB). These CB nanoparticles are both oil- and water-wettable. The hydrophilic/hydrophobic balance for the CB nanoparticles also causes them to form a network in the continuous aqueous phase. Upon drying this emulsion on a current collector, the CB particles located at the surfaces of the emulsion droplets form mesoporous cages that loosely encapsulate the Si particles that were in the oil. The CB particles that were in the aqueous phase form a conducting network connected to the CB cages. The space within the cages allows for Si particle expansion without transmitting stresses to the surrounding carbon network. Half-cell experiments using this Si/CB anode architecture show a specific capacity of ∼1300 mAh/g Si + C and a Coulombic efficiency of 97.4% after 50 cycles. Emulsion-templating is a simple, inexpensive processing strategy that directs Si and conducts CB particles to desired spatial locations for superior performance of anodes in lithium ion batteries.
硅（Si）因其高理论容量而有望成为锂离子电池负极材料。然而，在锂化/脱锂循环过程中，体积的大幅变化会导致硅粉化，从而使容量迅速衰减。在此，我们报告了一种简单的制备技术，旨在克服阻碍硅基负极更广泛应用的诸多限制。我们将硅纳米颗粒限制在由炭黑（CB）稳定的水包油乳液的油相中。这些炭黑纳米颗粒既亲油又亲水。炭黑纳米颗粒的亲水/疏水平衡还使其在连续水相中形成网络。在集流体上干燥该乳液后，位于乳液滴表面的炭黑颗粒形成介孔笼，松散地包裹油相中的硅颗粒。水相中的炭黑颗粒形成连接到炭黑笼的导电网络。笼内的空间允许硅颗粒膨胀而不将应力传递到周围的碳网络。使用这种硅/炭黑负极结构的半电池实验表明，经过50次循环后，比容量约为1300 mAh/g Si + C，库仑效率为97.4%。乳液模板法是一种简单、廉价的加工策略，可将硅和导电炭黑颗粒引导到所需的空间位置，以实现锂离子电池负极的卓越性能。
