A reconstructed graphite-like carbon (r-GC) micro/nano-structure with a higher capacity than and a comparative voltage plateau to commercial graphite anode of lithium-ion batteries (LIBs) is synthesized from expandable graphite raw material based on an up-down-up synthetic strategy. The expandable graphite powders are thermally expanded, hydrothermally cut, and ultrasonically crushed in turn to prepare a suspension containing nano-fragments with graphitic plane nano-structure as a carbon precursor. Then, the r-GC micro/nano-structure can be obtained by stacking the graphite nano-fragments through spray drying the suspension and subsequently conducting calcining treatment. This r-GC exhibits an initial capacity of 575.3 mAh g -1 at 0.1 C and a reversible capacity of 508.4 mAh g -1 after 100 cycles. Especially, its comparative voltage plateau of commercial graphite is incapable for other known anode materials of LIBs. In the potential window of 0.3-0.01 V (vs. Li + /Li), a maximum capacity of approximately 432.1 mAh g -1 , 1.16 times the theoretical capacity of graphite (372 mAh g -1 ), is obtained. The unique element stability, capacity, and voltage plateau indicate that the as-synthesized r-GC is a promising sheet-like anode material of LIBs. In addition, an embedded-defects and graphite-dominant graphite/graphene cooperative lithiation mechanism is proposed to elaborate the capacity and voltage plateau of r-GC. 5 through an up-down-up process, we synthesized a new reconstructed graphite-like carbon (r-GC) micro/nano-structure by restacking the graphite nano-fragments using expandable graphite powders as raw material. More importantly, it has been found that this r-GC exhibits a similar voltage plateau and an enhanced lithiation/delithiation capacity of graphite anode material. These results indicate that the as-synthesized r-GC can match the demand of LIBs with a higher energy, and the synthetic strategy opens up the possibility of manufacturing higher-capacity anode materials, particularly for sheet-like carbon-based materials. In this paper, the synthesis and characterization of r-GC are presented. In addition, an embedded-defects and graphite-dominant graphite/graphene cooperative lithiation mechanism is put forward to elaborate the higher capacity and low plateau of r-GC.
Experimental section
Synthesis of the r-GCExpandable graphite raw material, with an expansion ratio of 30 mL g -1 at 500 °C in air, was obtained from LiChang New Material Co. Ltd. (Dalian, China). After a high-temperature treatment, 0.5 g of expanded graphite (EG) was added into a 150-mL hydrothermal reactor with polytetrafluoroethylene lining. Afterwards, 30 mL H 2 O 2 (30 wt%) and 90 mL HNO 3 (5 mol L -1 ) were poured into the reactor, and then, the sealed reactor was transferred to an oven at 160 °C for 25 h. An ethanol/H 2 O (1:1 in volume) mixture was used to wash the hydrothermal product. Subsequently, the washed product was further ultrasonically crushed in 150 mL ethanol using an ultrasonic pulverizer (400
Results and discussionExpa...