A lithium-ion battery is made of four core components: a cathode (positive electrode), an anode (negative electrode), an electrolyte, and a separator. Each one is built from different raw materials, and the specific combination determines how much energy the battery stores, how long it lasts, and how safe it is. Despite the name, lithium itself makes up only about 2% of a battery’s total weight. The bulk comes from metals like nickel, graphite, and various polymers and solvents.
The Four Main Parts
Every lithium-ion cell works the same basic way. The cathode and anode store lithium atoms. The electrolyte, a liquid solution, shuttles lithium ions back and forth between those two electrodes. The separator sits between the cathode and anode, allowing ions to pass through while blocking electrons, which forces them to travel through an external circuit and power whatever device is connected. Two metal current collectors, typically made of copper on the anode side and aluminum on the cathode side, channel that electrical current in and out of the cell.
What the Cathode Is Made Of
The cathode is the most chemically complex part of the battery and the biggest factor in its performance. It’s always a lithium-containing compound, but the other metals mixed in vary widely. The two dominant families in today’s market are NMC and LFP.
NMC cathodes combine lithium with nickel, manganese, and cobalt in varying ratios. You’ll sometimes see shorthand like NMC811, which means 80% nickel, 10% manganese, and 10% cobalt. Higher nickel content means more energy density, so the battery stores more power per kilogram. That’s why NMC remains the dominant chemistry in the United States and Europe, especially for electric vehicles that need long range. A related variant, NCA, swaps manganese for aluminum and is used by some major EV manufacturers.
LFP cathodes use lithium, iron, and phosphate. They store less energy per kilogram (roughly one-fifth less than NMC by mass), but they’re cheaper, more thermally stable, and last longer through repeated charging cycles. LFP has been gaining ground fast. In 2024, it made up nearly half the global EV battery market, according to the International Energy Agency, and captured roughly three-quarters of battery demand in China. LFP packs cost about 30% less per kilowatt-hour than NMC packs, which is a major reason automakers are increasingly adopting them.
What the Anode Is Made Of
The anode in nearly all commercial lithium-ion batteries is graphite, a crystalline form of carbon. Graphite is the single heaviest material in a battery cell. In a typical 400 kg EV battery pack, about 71 kg is graphite, making it roughly 18% of the total weight. Graphite works well because it has a layered structure with tiny gaps between sheets of carbon atoms. Lithium ions slide in between those layers during charging and slide back out during discharge, a process called intercalation. The structure barely changes shape during this process, which is why graphite anodes hold up over thousands of charge cycles.
Some newer batteries blend silicon into the graphite anode. Silicon can bond directly with lithium atoms (an alloying reaction rather than intercalation), which allows it to store roughly ten times more lithium per gram than graphite alone. The tradeoff is that silicon swells dramatically during charging and can crack, so it’s typically used in small amounts mixed into a graphite base.
What the Electrolyte Is Made Of
The electrolyte is a liquid solution that fills the space between the electrodes. It has two components: a lithium salt dissolved in an organic solvent. The most common salt is lithium hexafluorophosphate, which provides the free lithium ions that carry charge through the cell. The solvents are carbon-based liquids like ethylene carbonate and dimethyl carbonate, chosen because they stay stable at the voltages inside the battery and dissolve the lithium salt effectively. These solvents are flammable, which is one reason battery safety engineering focuses heavily on preventing electrolyte leaks and overheating.
What the Separator Is Made Of
The separator is a thin, microporous plastic film, usually just a few micrometers thick. Its job is purely physical: let lithium ions pass through its tiny pores while keeping the two electrodes from touching each other (which would cause a short circuit). Most commercial separators are made from polyethylene or polypropylene, both common plastics with a semi-crystalline structure that creates the right pore size. Some manufacturers use more advanced polymers or coat the separator with ceramic particles for extra heat resistance.
How Much of Each Material Is in a Battery
The materials inside a lithium-ion battery are not evenly distributed. Based on data from Volkswagen for a 400 kg EV battery pack, the approximate breakdown of key recyclable materials is:
- Graphite: 71 kg (about 18% of total weight)
- Nickel: 41 kg (about 10%)
- Cobalt: 9 kg (about 2.3%)
- Lithium: 8 kg (about 2%)
The rest of the weight comes from aluminum and copper current collectors, the steel or aluminum casing, plastic separators, electrolyte solvents, and wiring. It’s a common surprise that lithium, the element the battery is named after, is actually one of the smallest ingredients by mass. Its importance comes not from quantity but from its unique electrochemical properties: lithium is the lightest metal on the periodic table and gives up electrons very easily, making it ideal for carrying charge between electrodes.
How the Chemistry Is Shifting
The industry is moving in two clear directions. First, battery makers are pushing to reduce or eliminate cobalt, which is expensive and concentrated in a small number of mining regions. High-nickel cathode formulations like NMC811 cut cobalt content significantly, and LFP eliminates it entirely. Second, LFP’s cost advantage is reshaping the market. While NMC batteries still win on energy density, the gap has been narrowing, and for many applications, the lower price and longer lifespan of LFP make it the better choice. In China, LFP’s market share hit 80% of batteries sold in the final months of 2024.
These shifts mean that the raw material profile of lithium-ion batteries is changing year by year. A battery built in 2025 may contain far less cobalt and far more iron and phosphate than one built five years ago, even though both go by the same “lithium-ion” label.