Graphene-like-Graphite for High Capacity and Fast Chargeable Anode Materials of Lithium Ion Batteries

Abstract

Electrochemical energy storage has become a critical technology for a variety of applications from portable electronics to electric vehicles. The lithium-ion (Li-ion) battery is the most promising energy storage devices because of its relative high energy density, power density and cycle life. However, a further increase of energy density and power presence is very limited in the last two decades since there is little progress in commercializing new electrode materials with significantly higher capacity and fast charging and discharging capability. To meeting the increasing demand for energy storage, novel and practical electrode materials with high capacity, fast chargeable capability, long cycle life, and the ability to be produced at large scale are of great interest. Silicon (Si) and transition metal oxides have been considered to be used for the anode materials of Li-ion batteries because the high theoretical capacity. However, the extreme volume change (~400%) experienced during lithiation/delithiation results in pulverization of the active material and loss of electrical connection leading to rapid capacity loss. In addition, the solid electrolyte interphase (SEI) layer which formed on the first cycle has to bear the same volume expansion and contraction, will also crack and delaminate from the Si, leading to a very thick layer of SEI after many cycles. Although some researcher are tried to use a core-shell structure, porous silicon, or hollow silicon sphere to solve this problem, it is still far from real application. At present, graphite is the most popular commercialized anode material for Li-ion battery because of its relative high capacity, long cycle life, low cost and ease of processing. However, the limited theoretical capacity (372mAh/g) and small interlayer spaces (0.335 nm) made it difficult to be used in the application of Li-ion battery with higher energy density and fast chargeable Li-ion batteries. Graphene, as the parent of all graphitic structures, has been studied as an anode material for high capacity and good rate performance. However, the graphene is hardly to be made into battery electrodes because of its low density and high specific surface area. In this study, we have introduced a novel graphene-like-graphite (GLG) anode material to be used in Li-ion batteries. Different from graphene materials with high surface area, the GLG has an unaltered shape and size compared with the conventional natural graphite. Moreover, the GLG has a stacked graphene structure with larger interlayer spaces which could accommodate lithium ion intercalation/deintercalation at a higher speed than pristine graphite. Most important of all, the capacity can be adjusted by controlling the content of oxygen, that the GLG can deliver a much higher capacity than graphite. The as synthesized material with capacity of 424mAh/g and good rate capability was characterized by XRD, Raman spectroscopy, FT-IR, TPD-MS, RBS, XPS. The GLG anode material has high potential to be used in Li-ion batteries anode with high capacity and fast charging capability.