Are there any moments in life, do you think science and technology are behind? !
Yes, when we disassemble the iPad, one of our most consumer-grade portable personal computers of our time, a sense of powerlessness swept through the body, and the middle one occupies the vast majority of black stuff in the entire machine What is it? Is the battery!
When the vibration motor can be so sophisticated, what is restricting the electronic products toward more secure and more lightweight development? Is the battery!
Ipad battery and shock motor obvious contrast
In order to replace the traditional lithium battery, researchers focus on the development of new lithium-ion batteries with excellent cycling properties. When the size of the particles and the nanostructure of the electrodes are reduced, the electrodes can work normally even in the lithiation and delithiation process even though the volume strain is large . Some researchers also pointed out that the coated (core - shell) morphology of the electrode material in the charge and discharge cycles in the low degree of depletion. However, new problems arise with electrode nanostructured materials: low volumetric capacity (low tap density) and high electrical resistance, resulting in increased manufacturing costs and low coulombic efficiency due to side reactions.
In view of the above problems, the anode composite material can solve these problems. The substrate composite anode material represented by graphene has the advantages of high conductivity, high mechanical strength, strong connection with lithium active components and rapid lithium ion transmission, There are several aspects: 1, there are limitations of the total capacitance potential. 2, synthetic technology is expensive. 3, the first cycle of large loss, low efficiency cycle.
Recently, Gurpreet Singh's research team abroad has synthesized ordered and interdependent large-area free-standing anode composite materials with SiOC and reduced graphene oxide (rGO) from the perspective of composite materials. This anode material has a higher volumetric capacity than reported Si / C nanotubes. The redox graphene sheets, as the substrate material for SiOC particles, combine to exhibit high electron transport channels, high cycling, high current density, High stability and so on. In addition to making up for defects in other types of lithium batteries, the first cycle has a high charge capacity (702 mA h g -1), a high constant charge capacity (543 mA h g -1) and high charge current density (2400 mA g -1) More noteworthy is that this composite anode material has excellent strain failure characteristics (more than 2%), which is more than pure paper-like reduced graphene oxide failure characteristics.
Silicon and graphene have high theoretical capacity is good lithium battery anode material, but its low energy density, low efficiency, poor stability and other issues limit its practical application. Here we report a free-standing anode material composed of carbon-silica glass particles embedded in a chemically modified graphene matrix. The simplified porous graphene oxide matrix, which is used as a highly efficient electron transporter, is a stable structure current collector that, when used with amorphous silicon oxycarbide, enables high lithium-ion battery efficiencies. At 1020 cycles, the energy density of the paper electrode reached 588 mAhg-1 without any sign of mechanical failure.
The article also points out the need to reduce some unnecessary materials, such as current collectors or polymer binders, to produce efficient, lightweight cells.
(A) Scanning electron micrograph of silicon carbon fine particles formed by pyrolysis of TTCS (1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane). It can be observed that the glassy particles are composed of submicron sized particles.
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