Enhanced electrochemical production and facile modification of graphite oxide for cost-effective sodium ion battery anodes

Sodium-ion batteries (SIBs) are emerging as an inexpensive and more sustainable alternative to lithiumion batteries in the energy storage market. To advance their commercialization, one major scientific undertaking is to develop low-cost, reliable anode materials from abundant resources, like the success of graphite in the lithium-ion batteries. However, graphite is chemically inactive in storing sodium ions and, to render it viable in sodium-ion batteries, additional modification of graphite is required. Herein, we demonstrate a green and facile method to prepare cost-effective and stable graphitic SIB anodes. The modification process started with the electrochemical oxidation of expanded graphite to widen the interlayer and functionalize graphite layers, followed by a fast (20 min) thermal treatment at 150 degrees C to achieve controlled deoxygenation. The thermally processed electrochemical graphite oxide could provide a high reversible capacity of 268 mAh g(-1) at 100 mA g(-1) and 163 mAh g(-1) at 500 mA g(-1) as well as low fading in capacity (in average 0.0198% loss per cycle) over 2000 cycles. The electrochemical route eliminates the need for the harsh chemical oxidation of graphite, offering a promising approach for industrial production of low-cost anodes for sodium-ion batteries. (c) 2021 Elsevier Ltd. All rights reserved.