One supplier quotes SPG. Another quotes CSPG. A third offers something called HPG. All three are marketed as “battery-grade natural graphite,” yet their prices differ widely, and they sell to entirely different buyers. If you’re new to the anode materials business, these natural graphite product grades can look like interchangeable jargon. They aren’t. Each one marks a different depth of processing: how pure the material is, whether the particles have been shaped into spheres, and whether the surface carries a carbon coating.
Getting these grades straight matters well beyond reading a price sheet. The grade you target determines how far your plant needs to go, which equipment it needs, and who your customers will be. This guide breaks down HPG, SPG, and CSPG from a process and plant-engineering perspective.
HPG (high-purity graphite) is natural graphite that has been purified but not spheroidized. SPG (spherical purified graphite) has been purified to about 99.95% carbon, then micronized and shaped into spheres, but remains uncoated. CSPG (coated spherical purified graphite) is SPG with a carbon coating applied, ready for use as lithium-ion battery anode material.
| Grade | Purity | Particle Shape | Surface Coating | Role in the Value Chain |
| HPG | ≥99.9% (battery-related uses typically require 99.95%) | Flake or standard fine powder | None | High-purity feedstock / intermediate |
| SPG | ~99.95% C | Spherical / near-spherical | None | Anode precursor, sold to coating plants |
| CSPG | ~99.95% C (core) | Spherical | Carbon coating | Finished anode material, sold to cell makers |
Where These Grades Sit in the Natural Graphite Value Chain
First, separate two ideas that often get blurred. Terms like flake, amorphous, and vein graphite describe the mineral’s natural morphology. HPG, SPG, and CSPG describe processed product grades: the same flake ore becomes a different commodity depending on how far you take it.
All three grades start from the same feedstock, flake concentrate (roughly 94–95% C), and each one adds a processing step to the last:
Flake concentrate → purification → HPG → micronization + spheroidization → SPG → coating + carbonization → CSPG
Producers don’t all run these steps in the same order. Some shape the flake first and purify afterward. In the purify-first route shown above, HPG is both a sellable product and the direct feed for spheroidization. Metallic contamination picked up during milling is then handled by a demagnetization step before the SPG ships. For the full sequence, see our complete natural graphite anode material production process.
Price reporting agencies now assess both ends of this chain against reference specifications: flake concentrate at 94–95% C and -100 mesh, and uncoated spherical graphite at 99.95% C and 15 µm. Think of those two specs as reference points for the rest of the value chain.
📊 Figure placement: Natural graphite value chain diagram (flake concentrate → HPG / SPG → CSPG), labeling the key process step and equipment at each stage.
What Is HPG (High-Purity Graphite)?
HPG stands for high-purity graphite: graphite that has been chemically or thermally purified to a high carbon content, but whose particle shape hasn’t been changed. It’s usually still flake or ordinary fine powder.
In academic classification, graphite with a carbon content of 99.9% or higher counts as high-purity. EV battery anodes, however, generally require 99.95%. In other words, “high purity” and “battery grade” aren’t the same thing. Going from 99.9% to 99.95% means cutting the remaining impurities roughly in half, and battery specs add tight, ppm-level limits on magnetic impurities such as iron and nickel. (For how producers hit those limits, see our complete guide to purity control for natural graphite anode materials.)
HPG mainly serves industrial applications that are sensitive to impurities but don’t need spherical particles. In a purify-first anode plant, it is also the direct feedstock for spheroidization.
Buyer’s Tip: Read the Spec Sheet, Not the Acronym
The industry doesn’t use “HPG” consistently. Some suppliers mean 99.9% purified flake, others mean ultra-high-purity material above 99.99%, and some apply the label to spherical products. When you sign a contract, what actually binds the supplier is the spec sheet: carbon content, ash, magnetic impurities, particle size distribution, and specific surface area. The product name on its own doesn’t bind anyone.
What Is SPG (Spherical Purified Graphite)?
SPG stands for spherical purified graphite, often called uncoated spherical graphite. According to the U.S. Geological Survey, SPG is made from natural flake concentrate that has been rounded, micronized, and purified to 99.95% carbon, and it is the specialized graphite form that feeds battery anode production.
Why round the flakes at all? Flat flakes tend to lie parallel to the current collector during electrode coating, which lowers packing density and lengthens the lithium-ion diffusion path. Shaping them into spheres raises tap density and improves both electrode processability and rate performance. We cover the mechanics and equipment trade-offs in What Is Natural Graphite Spheroidization and our spheroidization equipment comparison.
SPG production comes with an engineering reality you can’t avoid: spheroidization separates out a large share of fines and off-spec material, so overall yield is low. Whether those fines have a market, and how well the shaping and classification systems are matched, directly shapes the economics of an SPG project. Purifying before shaping helps here, because the fines come out as high-purity material rather than low-value waste. That math has to be done during line design, not patched after the equipment arrives.
On the trade side, most SPG produced in China has historically been uncoated, while anode producers in Japan and South Korea have traditionally imported SPG and applied their own coatings. That tells you SPG is a mature, tradable intermediate in its own right.
What Is CSPG (Coated Spherical Purified Graphite)?
CSPG stands for coated spherical purified graphite: SPG with a layer of amorphous carbon on its surface, and the finished anode product. The typical process coats SPG particles with a precursor such as pitch or resin, then carbonizes them at high temperature to turn that precursor into a stable carbon shell. For guidance on picking a precursor, see Pitch vs Resin: How to Select a Carbon Coating Precursor.
The coating does three main jobs:
- Protects the spherical structure. The carbon shell helps prevent the spheres from exfoliating and degrading. This matters especially for natural graphite, whose layered structure is vulnerable to damage from solvent co-intercalation during repeated cycling.
- Lowers effective surface area. Less exposed surface means fewer side reactions with the electrolyte, which reduces irreversible capacity loss on the first cycle and raises initial coulombic efficiency.
- Supports cycle life and rate capability. Well-engineered coatings help modified natural graphite deliver high first-cycle efficiency and strong capacity retention over hundreds of cycles, which is what cell makers ultimately qualify against.
CSPG has also been much slower than SPG to settle on a standard contract structure. The reason is simple: every cell maker sets its own targets for particle size distribution, specific surface area, first-cycle efficiency, and compaction density. CSPG is essentially a custom product that has to be qualified customer by customer. It carries the most value, and the highest barrier to entry.
SPG vs CSPG vs HPG: Side-by-Side Comparison
The difference between SPG and CSPG comes down to the carbon coating: SPG is uncoated spherical graphite sold as an intermediate, while CSPG is coated and ready for anode use. The difference between HPG and SPG is particle shape: both are purified, but only SPG has been spheroidized for battery use.
| Attribute | HPG | SPG | CSPG |
| Carbon content | ≥99.9%, depending on application | ~99.95% | ~99.95% (core) + carbon coating |
| Particle shape | Flake / standard fine powder | Spherical / near-spherical | Spherical with carbon shell |
| Typical particle size | Wide range, application-dependent | Benchmarked around 15 µm, with several size classes available | Customized to cell-maker specs |
| Usable directly as anode material? | No | Generally not; needs coating | Yes |
| Main buyers | Industrial users, high-purity feedstock buyers | Anode coating plants | Cell and battery manufacturers |
| Degree of standardization | Low (acronym used inconsistently) | Relatively high; recognized benchmark spec | Low; customized and qualified per customer |
| Relative added value | Medium | Medium-high | Highest |
| Key process steps / equipment | Purification | Purification, grinding, spheroidization, classification, demagnetization | All SPG steps plus coating granulation, carbonization, blending, screening |
Which Grade Should Your Plant Target? An Engineering Perspective
For new entrants, the most practical takeaway from that table is this: the grade you target defines the boundaries of your production line.
Stopping at SPG
Capital cost and process complexity stay manageable: the core of the line is purification, grinding, spheroidization, and classification. SPG has an established market and fairly standardized specs, which makes it a reasonable starting point. But SPG sits in the middle of the value chain, so margins get squeezed from both sides, and low yield shows up directly in your cost per ton.
Extending to CSPG
Adding coating granulation and carbonization on top of an SPG line lets you sell directly to cell makers, with a clear jump in added value. The core equipment at this stage is the coating granulation rotary kiln. It has to mix the precursor evenly with SPG, granulate the material, and manage the temperature profile within a single system. Whether the coating comes out uniform, and whether particles agglomerate, depends heavily on the kiln’s temperature-control accuracy and residence-time design. (See The Critical Role of the Coating Granulation Rotary Kiln.) The trade-off is tighter process control and a longer customer qualification cycle.
Building in Phases
If you’re still building up capital and a customer base, a practical path is to produce SPG in Phase 1 and extend to CSPG in Phase 2. The key is to reserve space, utility tie-ins, and material-handling connections for Phase 2 while you design Phase 1. If the building layout, dust collection system, and conveying routes don’t account for expansion from day one, retrofitting later usually costs far more than planning ahead would have. That’s where full-line EPC planning pays off compared with buying equipment piece by piece. For the bigger picture, see How to Build a Natural Graphite Processing Plant and From Lab to Pilot to Plant on managing scale-up risk.
Common Misconceptions When Buying or Specifying Graphite Grades
- “99.95% carbon means battery grade.” Carbon content is only one gate. Magnetic impurities, particle size distribution, specific surface area, and tap density are equally hard requirements, and every cell maker writes them into its own incoming-material specification.
- “Any CSPG can replace any other.” CSPG is a custom product. Switching suppliers usually means requalifying.
- “Buy the equipment now and decide the grade later.” Your target grade drives your equipment list. Settle the grade and the target customer first, then design the line. Otherwise you risk idle equipment or bottlenecks.
FAQ
Is SPG the same as spherical graphite? Essentially, yes. SPG refers specifically to spherical natural graphite that has been purified to battery-grade levels but not yet coated. When the market talks about “uncoated spherical graphite,” it usually means SPG.
Why is spherical graphite coated before it’s used in batteries? The coating protects the spherical structure and reduces side reactions with the electrolyte, which improves initial coulombic efficiency and cycling stability. Uncoated natural graphite used directly as an anode typically shows lower first-cycle efficiency and weaker cycling stability.
What purity is required for battery-grade graphite? EV battery anodes generally require 99.95% carbon, along with strict limits on trace impurities, especially magnetic ones.
Can high-purity flake graphite be used directly as anode material? Generally, no. High-purity flake may meet the purity target, but its flat shape hurts electrode processing and performance. It still needs spheroidization and coating.
Is CSPG made from natural or synthetic graphite? CSPG usually refers to products made from natural flake graphite. Synthetic graphite follows a separate route, starting from petroleum coke or needle coke and going through high-temperature graphitization. The two shouldn’t be confused.
Pick Your Grade First, Then Design Your Line
HPG, SPG, and CSPG aren’t just three acronyms. They represent three levels of processing, three customer bases, and three business models. For a new entrant, the most important decisions come before construction: What grade can your concentrate realistically reach? What specs do your target customers need? Should you build the full line at once or in phases?
As an equipment manufacturer and EPC contractor for natural graphite anode production lines, ZDZN can support you at every stage:
- Still mapping out your process? Start with our complete natural graphite anode material production process to see how each grade fits into a full production line.
- Have feedstock and weighing your options? Book a free technical consultation. Our engineering team will review your concentrate and recommend a realistic target grade and process route.
- Ready to move into a project? Request an SPG/CSPG full-line assessment covering capacity planning, equipment configuration (including the coating granulation rotary kiln and carbonization system), and a phased EPC implementation roadmap.