Concurrently Approaching Volumetric and Specific Capacity Limits of Lithium Battery Cathodes via Conformal Pickering Emulsion Graphene Coatings
Concurrently Approaching Volumetric and Specific Capacity Limits of Lithium Battery Cathodes via Conformal Pickering Emulsion Graphene Coatings
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DOI：
10.1002/aenm.202001216
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发表时间：
2020-05-18
影响因子：
27.8
通讯作者：
Hersam, Mark C.
中科院分区：
文献类型：
--
作者：
Park, Kyu-Young;Lim, Jin-Myoung;Hersam, Mark C.
为了实现新兴技术所要求的高能量密度，锂电池电极需要接近其电化学活性成分的体积和比容量限制，这需要最小化电极的非活性成分。然而，降低非活性导电添加剂的百分比限制了电池电极内的电荷传输，从而导致电化学性能受损。在这里，介绍了一种电极设计，可以在极低的导电添加剂水平和工业相关的活性物质面积负载下实现高效的电子和锂离子传输动力学。使用可扩展的Pickering乳液方法，富镍LiNi0.8Co0.15Al0.05O2 （NCA）阴极粉末仅使用0.5 wt%的溶液处理石墨烯进行保形涂层，从而获得与5 wt%炭黑相当的导电性。此外，保形石墨烯涂层减轻了阴极表面的降解，从而提高了电化学循环寿命。电极的形态也有利于快速的锂离子传输动力学，这提供了最高的速率能力。总的来说，这种电极设计同时接近理论体积和比容量限制，而不需要在循环寿命，速率能力或活性物质面积负载方面进行权衡。
To achieve the high energy densities demanded by emerging technologies, lithium battery electrodes need to approach the volumetric and specific capacity limits of their electrochemically active constituents, which requires minimization of the inactive components of the electrode. However, a reduction in the percentage of inactive conductive additives limits charge transport within the battery electrode, which results in compromised electrochemical performance. Here, an electrode design that achieves efficient electron and lithium-ion transport kinetics at exceptionally low conductive additive levels and industrially relevant active material areal loadings is introduced. Using a scalable Pickering emulsion approach, Ni-rich LiNi0.8Co0.15Al0.05O2 (NCA) cathode powders are conformally coated using only 0.5 wt% of solution-processed graphene, resulting in an electrical conductivity that is comparable to 5 wt% carbon black. Moreover, the conformal graphene coating mitigates degradation at the cathode surface, thus providing improved electrochemical cycle life. The morphology of the electrodes also facilitates rapid lithium-ion transport kinetics, which provides superlative rate capability. Overall, this electrode design concurrently approaches theoretical volumetric and specific capacity limits without tradeoffs in cycle life, rate capability, or active material areal loading.