As an electrode material for solar cells, graphite is widely used in the production of electrodes for solar cells due to its good electrical and thermal conductivity and good chemical stability.
At present, there are two main types of common graphite products on the market: one is artificial graphite (also known as natural graphite); The second is high-purity graphite (also known as semi-conductive graphite).
Artificial graphite is mainly composed of carbon atoms and is an inorganic non-metallic material that can be used to make electronic industrial products such as conductive pastes, conductive agents and carbon black. Its main use is as a conductive agent in the electronics industry to improve the efficiency of electrical energy utilization.
However, due to the poor conductivity, poor thermal conductivity, high coefficient of thermal expansion, poor thermal stability, low mechanical strength and other reasons of natural and semi-conductive artificial graphite, it cannot be directly used in solar cell electrodes.
Therefore, in the production process of solar cells, natural and semi-conductive artificial graphite need to be purified to improve its thermal and electrical conductivity. At the same time, it is necessary to improve its thermal expansion coefficient and mechanical strength.
In addition, artificial graphite, as one of the important raw materials in the photovoltaic industry, is mainly used in the production of anode materials for lithium-ion batteries, conductive agents for solar cells, electrode pastes and carbon black.
With the development of the photovoltaic industry to higher voltage levels, better requirements are put forward for electrode materials: on the one hand, it is necessary to improve the conductivity while ensuring high voltage; On the other hand, good thermal stability and mechanical strength are required to adapt to applications under harsh conditions.
Therefore, natural and semi-conductive artificial graphite has great advantages and has become one of the indispensable raw materials in the photovoltaic industry, which also makes natural and semi-conductive artificial graphene as the most widely used electrode material in the photovoltaic field receive more and more attention from the market.
1. Prepare new carbon-based electrode materials
Natural and semi-conductive artificial graphite as anode materials for lithium-ion batteries, combined with other functional materials such as carbon black and conductive polymers, can be used to prepare lithium-ion battery anode materials, which can effectively improve the power density and cycle life of batteries.
The deposition of carbon nanotubes by natural and semi-conductive artificial graphite to prepare carbon nanotube/graphite composites and use them as anodes of solar cells can effectively improve their power density, charge-discharge efficiency, rate performance and cycle life.
Carbon nanotube/graphene composites were prepared by a simple method using artificial graphite and carbon nanotubes as raw materials.
A mixture of carbon black and graphene is compounded as an additive and added to the polymer electrolyte to form a lithium-ion battery anode material.
2. New lithium-ion battery anode
With the development of high-energy-density lithium-ion batteries, higher requirements have been put forward for anode materials, especially for large capacity, long cycle, low cost and low lithium consumption.
Graphene has become one of the research hotspots of lithium-ion battery anode materials due to its high specific capacity.
In addition, carbon materials represented by graphite have gradually become a research hotspot in recent years.
3. New graphite-based lithium-ion battery electrode slurry
Graphene is widely used in the field of lithium-ion batteries because of its excellent electrocatalytic performance, and is an ideal material for the preparation of high-performance lithium-ion battery anodes, but its application in lithium-ion batteries is seriously affected due to its poor conductivity and large volume expansion after adsorption of lithium ions on the surface.
To solve this problem, scientists at Seoul National University in Korea used chemical vapor deposition (CVD) to grow graphene layers on the surface of graphite, and composite graphene layers with graphite sheets to obtain composite materials.
The results show that: (1) The composite structure not only solves the problem of easy agglomeration of graphene sheets, but also improves the mechanical properties of graphite sheets; (2) The surface of the graphene layer in the composite material contains a large number of organic groups, which can improve the reactivity of graphene and lithium salt; (3) The three-dimensional network structure formed in the composite materials can effectively suppress the contact resistance between particles in the battery and improve the electrochemical reaction kinetics.
4. Research and analysis of the preparation technology and key processes of conductive paste-anode
Electrode paste is made into a paste of electrode sheets and compounded with conductive additives to form a battery material with conductive paste as a conductive current collector, which is an important part of battery function, and its performance directly affects battery performance.
The preparation technology of conductive paste-anode includes graphite purification technology, lithium-ion battery electrode preparation technology and graphite electrode preparation technology.
The conductive slurry is mainly composed of conductive agent or anode material, which can be added to the electrolyte as a lubricant during electrode processing to increase the contact area between the electrode and the electrolyte, shorten the ion diffusion path, and increase the reaction rate and reaction depth to reduce costs.