The rapid expansion of the new energy industry is driving a surge in demand for high-performance anode materials. As a key material, the production volume and quality requirements for hard carbon are rising accordingly. Efficient and precise processing equipment is at the heart of meeting these demands. This article explores the manufacturing of hard carbon and the critical role played by jet milling technology.
Hard carbon refers to a type of pyrolytic carbon. It’s obtained from the pyrolysis of polymers, petrochemical products, biomass, etc., and is classified as non-graphitizable carbon. This is because the precursor contains numerous heteroatoms such as H, O, and N, which hinder the formation of crystalline domains during heat treatment. It makes it difficult to graphitize even at high temperatures above 2500°C.
Depending on the pyrolysis carbonization temperature, hard carbon materials can be divided into two types. They’re high-temperature pyrolytic carbon (between 1000~1400°C) and low-temperature pyrolytic carbon (between 500~1000°C). Based on the carbon source, they can be categorized into resin carbon (e.g., phenolic resin, epoxy resin, polyfurfuryl alcohol resin, etc.), organic polymer carbon (e.g., PVA, PVC, PVDF, PAN, etc.), carbon black (e.g., acetylene black produced by CVD method), biomass carbon (e.g., plant residues and shells, etc.), and others.
The струйная мельница pulverizers from Epic Powder are engineered for high efficiency and minimal contamination. By using our pulverizers, you can process hard carbon to a fine powder ranging from 1 to 50 microns. This makes it perfectly suited for the electronics industry, particularly in conductive pastes and advanced carbon additives.
Hard carbon facilitates the intercalation of lithium without causing significant structural expansion, and exhibits good charge-discharge cycle performance. Hard carbon used as an anode material in lithium-ion batteries is primarily manufactured from precursors. The precursors include pitch-based, biomass-based, and resin-based materials, etc.
Precursors for manufacturing hard carbon include asphalt, biomass, sugar, phenolic resin, organic polymers, etc. Hard carbon materials produced from different substances show similar charge-discharge curves.
① Manufacturing Hard Carbon from Pitch
Pitch-based precursors are excellent for preparing hard carbon due to their high carbon residue rate, wide range of raw material sources, and low cost. However, manufacturing hard carbon from pitch requires pretreatment because pitch tends to graphitize and easily forms graphite-like structures during carbonization. Pitch pretreatment typically involves using cross-linking agents to cross-link the pitch, modify its microstructure, hinder the growth of graphite crystals during pyrolysis carbonization, and carry out solid-phase carbonization to obtain hard carbon materials. Another pitch manufacturing method is pre-oxidation. It uses oxidizing agents to pre-oxidize the pitch, obtaining pre-oxidized pitch with a specific oxygen content. Due to the presence of oxygen heteroatoms, the pitch struggles to form an ordered structure during pyrolysis and carbonization. This results in hard carbon materials with a relatively disordered microstructure.
② Manufacturing Hard Carbon from Biomass
Biomass boasts diverse sources, is environmentally friendly, green, and contains abundant heteroatoms and unique microstructures, making it suitable as a precursor for hard carbon manufacturing. Some researchers have used grapefruit peel as a carbon source to prepare hard carbon materials. Their studies believe that the excellent lithium intercalation performance of the prepared samples is closely related to the material’s unique pore structure. This structure helps the material make full contact with the electrolyte and provides channels for Li+ transport within the material, as well as more lithium intercalation sites.
③ Manufacturing Hard Carbon from Organic Polymers
Compared to biomass, the molecular structure of organic polymers is relatively simple and controllable. Relevant molecular structures can be designed as needed, making them outstanding precursors for hard carbon manufacturing. Some researchers have used phenolic resin as a carbon precursor, obtaining resin-based hard carbon materials through pyrolysis and carbonization, and utilized them as anode materials for lithium-ion batteries and electrode materials for supercapacitors. The lithium-ion battery capacity can reach 526 mAh·g⁻¹, and the initial Coulombic efficiency can reach up to 80%.
The above is an introduction to the characteristics of hard carbon and its manufacturing methods. Hard carbon possesses a rich microporous structure and a layered structure with a larger interlayer spacing than graphite. It enables rapid deintercalation of lithium ions and exhibiting excellent rate performance. Some hard carbon materials have higher lithium storage performance than traditional graphite anode materials. Consequently, hard carbon is also considered a promising anode material. It is believed that with technological advancements and in-depth research, the application of hard carbon materials in lithium battery anodes will also develop its own unique standing.
At Epic Powder, we specialize in tailored carbon powder making solutions. Our integrated systems can transform raw hard carbon precursor into finished powders with customizable particles (D97 3-45µm). This enables its use in a broad spectrum of industries, including aerospace (composites), metallurgy (recarburizers), and consumer electronics.
Эпический порошок
With the growing demand for anode materials, the production volume and quality of hard carbon have also seen significant improvement. The jet milling from Эпическая Порошковая Машина is capable of producing high-purity ultrafine hard carbon to meet your production needs. Feel free to contact us for a customized solution.
