Effects of Graphene Nanosheets with Different Lateral Sizes as Conductive Additives on the Electrochemical Performance of LiNi0.5Co0.2Mn0.3O2 Cathode Materials for Li Ion Batteries

Ting-Hao Hsu; Wei-Ren Liu

doi:10.3390/polym12051162

Effects of Graphene Nanosheets with Different Lateral Sizes as Conductive Additives on the Electrochemical Performance of LiNi_0.5Co_0.2Mn_0.3O₂ Cathode Materials for Li Ion Batteries

Polymers (Basel). 2020 May 19;12(5):1162. doi: 10.3390/polym12051162.

Authors

Ting-Hao Hsu¹, Wei-Ren Liu¹

Affiliation

¹ Department of Chemical Engineering, R&D Center for Membrane Technology, Research Center for Circular Economy, Chung Yuan Christian University, 200 Chung Pei Road, Chung Li District, Taoyuan City 32023, Taiwan.

Abstract

In this study, we focus on lateral size effects of graphene nanosheets as conductive additives for LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) cathode materials for Li-ion batteries. We used two different lateral sizes of graphene, 13 (GN-13) and 28 µm (GN-28). It can be found that the larger sheet sizes of graphene nanosheets give a poorer rate capability. The electrochemical measurements indicate that GN-13 delivers an average capacity of 189.8 mAh/g at 0.1 C and 114.2 mAh/g at 2 C and GN-28 exhibits an average capacity of 179.4 mAh/g at 0.1 C and only 6 mAh/g at 2 C. Moreover, according to the results of alternating current (AC) impedance, it can be found that the GN-28 sample has much higher resistance than that of GN-13. The reason might be attributed to that GN-28 has a longer diffusion distance of ion transfer and the mismatch of particle size between NCM and GN-28. The corresponding characterization might provide important reference for Li-ion battery applications.

Keywords: Li-ion batteries; cathode; conductive additives; graphene.