Graphene Nanoplatelet Additives for High C-rate LiFePO 4 Battery Cathodes
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https://doi.org/10.1007/s11837-020-04224-2 Ó 2020 The Minerals, Metals & Materials Society
QUANTUM MATERIALS FOR ENERGY-EFFICIENT COMPUTING
Graphene Nanoplatelet Additives for High C-rate LiFePO4 Battery Cathodes ADEWALE A. ADEPOJU,1 MOHAMED DOUMBIA,1 and QUINTON L. WILLIAMS 1,2 1.—Department of Physics and Astronomy, Howard University, Washington, DC 20059, USA. 2.—e-mail: [email protected]
Graphene nanoplatelets (GNPs) were introduced as conductive additives in the lithium iron phosphate (LiFePO4) composite cathode material through a facile slurry approach to study the effect on battery performance at high current rates (C-rates). The incorporation of GNPs helps to create a flexible three-dimensional conductive network through a plane-to-point connection with the LiFePO4 particles. Comparison electrochemical testing showed that the LiFePO4/GNP cathode exhibited a high specific discharge capacity of 153 mAh g 1 at 0.1C, improved high C-rate performance, and enhanced electrochemical reactivity. The enhanced LiFePO4/GNP battery performance can be attributed to the better electronic transport properties facilitated by the capability of GNP to bridge multiple LFP particles owing to its larger surface area. Our results inform the ongoing effort in finding LiFePO4 cathodes that can perform at high current rates as the demand increases for lithium-ion battery usage.
INTRODUCTION The continuous increase in universal energy demand, along with its devastating impact on our climate, in the form of climate change and global warming, has intensified research efforts in clean energy alternatives such as lithium-ion batteries (LIBs).1 Owing to their high energy density, low self-discharge rates, and portability, LIBs now serve as the state-of-the-art power source for present-day consumer electronics, power tools, and some medical devices.2–5 Larger application market targets now exist for LIBs as the power source of choice for hybrid electric vehicles (HEVs) and electric vehicles (EVs). Automotive industries are now heavily investing in research and development of advanced batteries capable of meeting the energy, cost, and safety requirements of HEVs and EVs.6,7 LiFePO4 (LFP), with its olivine crystal structure, has recently emerged as one of the leading alternative LIB cathode materials because of its excellent structural and thermal stability, long cycling life, high theoretical specific capacity ( 170 mAh g 1), low cost, and safe handling.8–10 However, a significant drawback to the practicability of LFP is its poor electronic conductivity ( 10 9 S cm 1, which
limits its performance at high capability rates (Crate).11,12 A typical, low cost, and most effective approach is the application of a conductive carbon coating/additive.13,14 Today, commercially produced LFP cathode particles are naturally embedded in a low-fraction matrix of residual carbon for improved conductivity.15 However, for higher C-rate performance, other approaches are necessary. Advanced carbon materials, including carbon nanotubes, carbon n
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