graphene-like-graphite as fast-chargeable and high-capacity anode materials for lithium ion batteries

Here, we propose the use of a carbon material called graphene --like-graphite (GLG)
As a negative material for lithium ion batteries, it has a capacity of up to 608 mAh/g and has excellent rate performance.
The morphology and crystal structure of GLG is very similar to the graphite currently used as a negative material for lithium ion batteries.
Therefore, it is expected that it will be used to manufacture batteries in the same way as conventional graphite materials.
Based on the data obtained by various spectral techniques, we propose a structural GLG model in which the nano-holes and C-PairsO-
Unit C is introduced in a carbon layer stacked with three units
Regular size.
Three types of high ion lithium ions were found in a fully charged GLG and stored between its layers.
The oxygen atoms introduced in the carbon layer seem to play an important role in accommodating a large amount of lithium ion in GLG.
In addition, for fully charged GLG, a significant increase in the observed layer spacing is attributed to the migration of oxygen atoms in the carbon layer introduced in the C-StateO-
C to maintain the mezzanine space of one of the C-O bonds. Among energy-
Lithium ion storage technology (Li-ion)
Because of its relatively high energy density, power density and long cycle life, the battery has become the key to a variety of applications from portable electronics to electric vehicles.
Recently, autonomous transport robots such as electric vehicles, unmanned aircraft and autonomous driving have aroused great interest in the country. of-the-
Art and Technology.
However, for the widespread use of these technologies, batteries with only high energy density are not enough to serve as a power source for these applications, as fast charging capability, long cycle life and low cost are also essential.
Further improvements in energy density and power performance have become very limited over the last 20 years, as new chemistry is being commercialized for higher capacity, fast-
Ability to charge and discharge.
Silicon and transition metal oxides are considered anode materials for lithium
The ion battery is due to its high theoretical capacity.
However, a very high volume change (~400%)
The result experienced during the process of lithium conversion/lithium removal is the crushing of the active substance and the loss of the electrical connection.
In addition, the solid electrolyte interface (SEI)
Layers formed during the 1st cycle must bear the same volume expansion and shrinkage and will also crack and strip from Si, resulting in a very thick SEI layer after several cycles, resulting in rapid loss of production capacity.
While some researchers are trying to use a core
To solve these problems, there is far from a real application. Regarding fast-
Charging capacity, reported with 2-
C. charging capacity, but the density is quite low, not practical.
For the above reasons, carbon material is the most popular commercial lithium anode material at present
Ion batteries are favored because of their relatively high capacity, long cycle life, low cost and easy processing.
However, limited theoretical capacity (372 mAh/g)
Small mezzanine space (0. 335u2009nm)
This makes it difficult to use in the application of Li-
Ion batteries with higher energy density and fast charging capability.
In this case, graphene, as the parent of all graphite structures, has been studied as an anode material with high capacity and good rate performance.
However, graphene is rarely used for battery electrodes due to low density and high specific surface area, resulting in low initial Cullen efficiency.
The density of the material is much lower than 0.
8g/cc, not suitable for use in batteries with high volume energy density.
However, we have previously reported thermal reduction of graphite peroxide (GO)
Large layer spacing is provided for carbon materials, but the surface area is low, maintaining a high regularity of graphene layer orientation.
Only when the temperature-
The growth rate in the GO thermal reduction process is low enough to avoid it falling off.
When the thermal reduction GO is used as an anode for Li-
Ion battery, shape of charge-
The discharge curve is similar to the recently reported graphene-Basic materials.
Interestingly, the thermal restore of GO presents the mezzanine space of 0.
34 u2009 nm, slightly larger than the original graphite;
However, the mezzanine space of the thermal reduction GO has increased by 0.
12 nm after full lithium.
This value is much larger than that one (0. 03u2009nm)
Graphite with the same state of charge was observed.
As a result, the capacity of some thermal reduction GO samples has been greatly increased by 580 mAh/g.
Therefore, we conclude that Li ions are stored on both sides of the graphene layer.
Recently, similar materials have been used for electric double electrodes.
Layer Capacitors with higher capacity and rate capability.
Large ions, such as trifluoride (
BF)
And methyl ammonium ((CH)N)
It is also considered to be the result of Van der Waals energy reduction between adjacent graphene layers.
These show that the carbon layers in this material are like independent graphene, although they are regularly oriented like carbon layers in graphite.
Therefore, we call this material \"graphene-like-graphite” (GLG).
We also report the insertion of Na Ions in GLG with a spacing of 0.
34 u2009 nm very similar to graphite, and residual oxygen in C-formO-
C promotes the reduction of GLG.
In this study, we study in detail the structure, electrochemical properties of GLG, and propose a structural model of GLG, in which Nano-holes and C-PairsO-
The C unit is introduced in a carbon layer with three dimensional regularity.