Lithium-Ion and Beyond

The lithium-ion battery is the most important energy-storage technology of the twenty-first century. It powers the phones in our pockets, the laptops on our desks, and the electric vehicles that are transforming the world’s transport systems. The story of how a chemistry discovered in the 1970s came to dominate the storage market — and what comes next — is, in retrospect, one of the most consequential materials-science stories of our time.

Why batteries matter

The story of the lithium-ion battery is, in the first instance, a story of portable electronics. The first commercial lithium-ion battery, sold by Sony in 1991, replaced the nickel-cadmium and nickel-metal-hydride batteries that had dominated portable electronics for decades. The new battery had twice the energy density of the old ones, no memory effect, and a much lower self-discharge rate. It was the enabling technology for the mobile electronic revolution: the camcorders of the 1990s, the mobile phones of the 2000s, the smartphones and tablets of the 2010s. By 2024, the global production of lithium-ion batteries was more than 2,000 GWh per year, more than the annual production of all other rechargeable battery chemistries combined.[1, 2, 9]

The second story is electric vehicles. The first modern electric car, the General Motors EV1, was introduced in 1996 and had a lead-acid battery pack with a range of about 70 miles. The first mass-market lithium-ion electric car, the Tesla Roadster, was introduced in 2008 and had a range of more than 200 miles. The combination of lithium-ion batteries, high-power electric motors, and a global charging network has made the electric car a practical alternative to the internal-combustion car. In 2024, more than 17 million electric cars were sold worldwide, more than 20 percent of the global new-car market. The transition is now irreversible.[2, 3, 10]

The third story is grid-scale storage. The cost of solar photovoltaic electricity has fallen by more than 90 percent since 2010, and the cost of wind electricity has fallen by more than 70 percent. Both are now cheaper, in most markets, than electricity from new fossil-fuel power stations. The problem is variability: the sun does not always shine, and the wind does not always blow. The solution is storage, and the cheapest storage technology, for durations of 4–12 hours, is now the lithium-ion battery. The global installed capacity of grid-scale battery storage grew from 1 GW in 2015 to more than 100 GW in 2024, and is expected to grow to more than 1 TW by 2030. The transition to a renewable electricity system depends, in significant part, on the continued cost reduction of battery storage.[3, 4, 11]

The basic electrochemistry

A lithium-ion cell has two electrodes and an electrolyte. The negative electrode, the anode, is typically graphite; the positive electrode, the cathode, is typically a lithium metal oxide such as lithium cobalt oxide (LCO), lithium nickel manganese cobalt oxide (NMC), lithium iron phosphate (LFP), or lithium nickel cobalt aluminium oxide (NCA). The electrolyte is a lithium salt (typically lithium hexafluorophosphate, LiPF6) dissolved in an organic solvent (typically a mixture of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate). A porous polymer separator (typically polyethylene or polypropylene) physically separates the two electrodes to prevent short circuits, while allowing lithium ions to pass through.[3, 4, 12]

During discharge, lithium atoms at the anode are oxidised to lithium ions, releasing electrons that flow through the external circuit. The lithium ions migrate through the electrolyte to the cathode, where they are inserted into the crystal structure of the cathode material. During charging, the process is reversed: an external voltage forces the lithium ions back to the anode, where they are reduced and inserted into the graphite. The voltage of the cell is set by the difference in the chemical potential of the two electrodes, and is typically 3.6–3.8 V for a fully charged cell, depending on the cathode chemistry. The capacity is set by the amount of lithium that can be stored in each electrode, and is typically measured in milliamp-hours per gram (mAh/g) of active material.[3, 4, 12]

The engineering of a real lithium-ion cell is, of course, much more complex than this basic picture suggests. The electrodes are not simple blocks of material but porous composites, with active material particles mixed with carbon black (for electronic conductivity) and a polymer binder (for mechanical integrity), coated onto a thin metal foil (copper for the anode, aluminum for the cathode). The electrolyte must wet the pores but not react with the active material. The separator must be thin (typically 20–25 micrometres) but mechanically strong. The cell must be sealed to prevent water ingress, which would react with the electrolyte to produce hydrofluoric acid. The result is a device that is, in mass production, remarkably cheap, and that contains, in a single cell, more engineering per dollar than almost any other consumer product.[3, 4, 12]

Lithium-ion: the chemistry that won

The lithium-ion battery was the result of research at three institutions in the 1970s and 1980s. M. Stanley Whittingham, at Exxon, demonstrated the concept in 1976 with a lithium-metal anode and a titanium disulfide cathode. The cell had a high energy density but was unsafe (lithium metal formed dendrites that shorted the cell). John Goodenough, at Oxford, showed in 1980 that a lithium cobalt oxide cathode gave a higher voltage and a better safety profile. Akira Yoshino, at Asahi Kasei, showed in 1985 that a carbonaceous anode (petroleum coke) could replace lithium metal, and that the cell was safe and long-lived. Sony commercialised the technology in 1991, and the rest is history.[2, 3, 13]

The chemistry of the cathode has evolved significantly since 1991. The original Sony cell used lithium cobalt oxide, which has a high energy density but is expensive (cobalt is scarce and toxic) and unstable at high temperatures. In the 2000s, lithium nickel manganese cobalt oxide (NMC) became dominant for electric vehicles, with a 1:1:1 ratio of nickel, manganese, and cobalt; the trend has been to increase the nickel content (NMC 622, NMC 811) to boost the energy density. In the 2010s, lithium iron phosphate (LFP) re-emerged as a competitive chemistry, particularly in China; LFP has a lower energy density than NMC but is cheaper, safer, and uses abundant materials. In 2024, LFP accounts for about 40 percent of the global EV battery market, and NMC and NCA for the rest. The cathode chemistry, in other words, is bifurcating: high-nickel for range, LFP for cost.[3, 4, 14]

The anode has also evolved. The original Sony cell used a graphitic carbon, which has a capacity of about 372 mAh/g. The trend has been to add silicon, which has a much higher capacity (about 4,200 mAh/g for Li22Si5) but swells by 300 percent on lithiation, which cracks the electrode. The solution, in commercial cells, is to use a silicon oxide or a silicon-graphite composite, with the silicon content typically 5–20 percent. Tesla, in 2023, started using a higher-silicon anode in its 4680 cells, and several Chinese manufacturers are following. The next step, still in research, is a pure lithium-metal anode, with a capacity of 3,860 mAh/g, more than ten times that of graphite. The challenge, as always, is the dendrites.[3, 4, 15]

The limits of lithium-ion

The energy density of the best commercial lithium-ion cells is now about 250–300 Wh/kg at the cell level, and about 200–250 Wh/kg at the pack level. The theoretical maximum, for a lithium-ion cell with a graphite anode and a layered-oxide cathode, is about 400 Wh/kg. The path to higher energy density is well understood: replace the graphite with silicon (or lithium metal), replace the layered oxide with a sulfur or oxygen cathode. Each of these chemistries has serious problems that have, so far, prevented commercialisation. The transition to higher energy density is, in other words, slow and difficult, and the industry has settled into a regime of incremental improvement rather than radical change.[4, 5, 16]

The other limits are supply chain. The lithium-ion battery requires lithium, cobalt, nickel, copper, graphite, and a small amount of other materials. Lithium is concentrated in Australia, Chile, and China; cobalt in the Democratic Republic of Congo; nickel in Indonesia, the Philippines, and Russia; graphite in China. The supply chain is, in this sense, more concentrated than the oil supply chain, and is more vulnerable to political disruption. The price of lithium carbonate, for example, spiked from about $6,000 per tonne in 2020 to about $80,000 per tonne in 2022, before falling back to about $15,000 per tonne in 2024. The volatility is a sign of an immature supply chain that has not yet caught up with the demand.[4, 5, 17]

The environmental and social costs of the supply chain are also a concern. Lithium extraction, in the salt flats of Chile and Argentina, consumes large amounts of water in arid regions. Cobalt mining, in the DRC, has been associated with child labour and dangerous working conditions. Nickel mining, in Indonesia, has caused deforestation and water pollution. The response, in the industry, has been a combination of certification schemes (the Initiative for Responsible Mining Assurance), of recycling (which now provides about 10 percent of the cobalt supply), and of alternative chemistries (LFP, sodium-ion) that avoid the most problematic materials. The transition, in other words, is not only technical but ethical.[4, 5, 18]

The alternatives: sodium-ion, solid-state, flow batteries

The alternatives to lithium-ion are real, and one of them — sodium-ion — is already in mass production. Sodium-ion batteries use the same basic electrochemistry as lithium-ion but with sodium ions instead of lithium ions. The energy density is lower (100–160 Wh/kg) than lithium-ion, but the materials are much cheaper (sodium is the sixth most abundant element in the Earth’s crust, and is widely available as sodium carbonate from mining and from the chlor-alkali industry). The supply chain is also more secure, since sodium is not concentrated in a small number of countries. Sodium-ion is well-suited to grid-scale storage, to low-end EVs (where weight is not critical), and to applications where cost is more important than energy density. CATL launched the first mass-produced sodium-ion battery in 2023, and several Chinese automakers (notably BYD and JAC) are using it in low-end EVs.[5, 6, 19]

Solid-state batteries replace the liquid electrolyte with a solid one — typically a ceramic such as lithium phosphorus oxynitride (LiPON) or a sulfide such as Li10GeP2S12 — and allow the use of a lithium-metal anode. The energy density can be 50–100 percent higher than conventional lithium-ion, the safety is better (no flammable liquid electrolyte), and the cycle life can be longer. The challenges are manufacturing (the solid electrolyte is brittle and difficult to process at scale), interface resistance (the contact between the solid electrolyte and the electrodes is a source of impedance), and cost (the materials and the processes are more expensive than for liquid electrolytes). The most credible solid-state programmes are at Toyota (with a target of 2027–2028 for limited production), QuantumScape (backed by Volkswagen), and Solid Power (backed by BMW and Ford). The first solid-state products are likely to be in consumer electronics, not in EVs.[5, 6, 20]

Redox flow batteries are a different class of storage. The active material is not in the electrodes but in liquid electrolytes held in external tanks; the cell stack is just a converter from electrical to chemical energy and back. The most common chemistry is vanadium redox, but iron, zinc, and organic chemistries are also in use. The energy capacity scales with the size of the tanks, and the power capacity scales with the size of the cell stack, so the two can be designed independently. This makes flow batteries well-suited to long-duration storage (8–100 hours), where the cost of the cell stack is amortised over a very large amount of energy storage. The largest flow battery in the world, in Dalian, China, has a capacity of 400 MWh and a power of 100 MW, enough to power 200,000 homes for two hours.[5, 6, 21]

Grid-scale storage and the energy transition

Grid-scale storage is the next bottleneck of the energy transition. The cost of solar and wind electricity has fallen below the cost of fossil-fuel electricity in most markets, but the variability of solar and wind is a problem: the sun does not always shine, and the wind does not always blow. The solution is storage, and the most economical storage technology, for durations of 4–12 hours, is now the lithium-ion battery. The global installed capacity of grid-scale battery storage grew from 1 GW in 2015 to more than 100 GW in 2024, and is expected to grow to more than 1 TW by 2030. The largest single installation, the Moss Landing Energy Storage Facility in California, has a capacity of 750 MW / 3,000 MWh, more than three times the capacity of the next-largest battery in the world.[6, 7, 22]

The bottleneck, in 2024, is not the cost of the batteries but the supply chain. Lithium, cobalt, nickel, and graphite are all concentrated in a small number of countries, and the mining and refining capacity is not keeping up with the demand. The response, in the industry, is a combination of diversification (mining projects in new regions, recycling, alternative chemistries) and substitution (LFP, sodium-ion). The transition will take years, and the supply chain will be a constraint on the pace of the energy transition in the 2020s. By the 2030s, however, the supply chain is expected to have caught up, and the bottleneck will move elsewhere.[6, 7, 23]

The other big story in grid-scale storage is long-duration storage. Lithium-ion is well-suited to 4–12 hour storage, but for longer durations (days, weeks, seasons), other technologies are needed. The candidates include pumped hydro (the dominant form of grid storage worldwide, with more than 160 GW installed), compressed air energy storage (CAES), flow batteries, and — for seasonal storage — the production of hydrogen by electrolysis and its storage in underground caverns. The economics of long-duration storage are still uncertain, but the technology is in place, and the deployment is expected to accelerate in the late 2020s and 2030s.[6, 7, 24]

Comparison: leading battery chemistries (2024)

Chemistry	Cathode	Anode	Cell energy density (Wh/kg)	Cycle life	Cost ($/kWh, 2024)	Best suited to
LFP (lithium iron phosphate)	LiFePO4	Graphite	160	3,000+	$80–110	Entry EVs, grid storage
NMC 811 (high-nickel)	LiNi0.8Mn0.1Co0.1O2	Graphite / Si	250–280	1,500–2,500	$110–150	Long-range EVs, premium electronics
NCA (Tesla)	LiNi0.8Co0.15Al0.05O2	Graphite / Si	260–300	1,000–1,500	$130–170	Long-range EVs
Sodium-ion	Na3V2(PO4)3 or Prussian blue analogues	Hard carbon	100–160	2,000–4,000	$80–120	Entry EVs, grid storage, low-cost
Solid-state (in development)	NMC or LFP	Lithium metal	350–500 (target)	1,000+ (target)	$200+ (target)	Premium EVs, long-range
Vanadium redox flow	V3+/V2+ (neg), V4+/V5+ (pos)	(liquid)	20–35	10,000+	$200–400	Long-duration grid storage (8–100 hours)

Key numbers

• ~$140: cost of a lithium-ion battery pack, per kWh (2024).
• ~2,000 GWh: global production of lithium-ion batteries per year (2024).
• ~17 million: electric vehicles sold worldwide (2024).
• ~100 GW: global installed capacity of grid-scale battery storage (2024).
• ~3,000 MWh: capacity of the Moss Landing Energy Storage Facility (world’s largest, California).
• ~400 MWh: capacity of the Dalian flow battery (world’s largest, China).
• ~$15,000: price of lithium carbonate per tonne (2024).
• ~80,000: peak price of lithium carbonate per tonne (2022).

References

1. Wikipedia, “Lithium-ion battery.” (Standard reference on the lithium-ion battery, with a section on the history.) https://en.wikipedia.org/wiki/Lithium-ion_battery
2. Wikipedia, “John B. Goodenough.” (Standard reference on John Goodenough, co-recipient of the 2019 Nobel Prize in Chemistry.) https://en.wikipedia.org/wiki/John_B._Goodenough
3. Wikipedia, “Akira Yoshino.” (Standard reference on Akira Yoshino, co-recipient of the 2019 Nobel Prize in Chemistry.) https://en.wikipedia.org/wiki/Akira_Yoshino
4. Wikipedia, “M. Stanley Whittingham.” (Standard reference on M. Stanley Whittingham, co-recipient of the 2019 Nobel Prize in Chemistry.) https://en.wikipedia.org/wiki/M._Stanley_Whittingham
5. Wikipedia, “Sodium-ion battery.” (Standard reference on the sodium-ion battery.) https://en.wikipedia.org/wiki/Sodium-ion_battery
6. Wikipedia, “Solid-state battery.” (Standard reference on the solid-state battery, with a section on the leading development programmes.) https://en.wikipedia.org/wiki/Solid-state_battery
7. Wikipedia, “Vanadium redox battery.” (Standard reference on the vanadium redox flow battery.) https://en.wikipedia.org/wiki/Vanadium_redox_battery
8. Wikipedia, “Grid energy storage.” (Standard reference on grid-scale energy storage, with capacity data.) https://en.wikipedia.org/wiki/Grid_energy_storage
9. Wikipedia, “Electric vehicle battery.” (Standard reference on EV batteries, with cost and energy density data.) https://en.wikipedia.org/wiki/Electric_vehicle_battery
10. Wikipedia, “Tesla Roadster (first generation).” (Standard reference on the original Tesla Roadster, the first modern lithium-ion EV.) https://en.wikipedia.org/wiki/Tesla_Roadster_(first_generation)
11. Wikipedia, “Moss Landing Energy Storage Facility.” (Standard reference on the Moss Landing battery, the world’s largest.) https://en.wikipedia.org/wiki/Moss_Landing_Energy_Storage_Facility
12. Wikipedia, “Lithium iron phosphate battery.” (Standard reference on the LFP battery chemistry.) https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery
13. Wikipedia, “Lithium nickel manganese cobalt oxides.” (Standard reference on the NMC battery chemistry.) https://en.wikipedia.org/wiki/Lithium_nickel_manganese_cobalt_oxides
14. Wikipedia, “CATL.” (Standard reference on CATL, the world’s largest battery manufacturer.) https://en.wikipedia.org/wiki/CATL
15. Wikipedia, “BYD Company.” (Standard reference on BYD, the second-largest battery manufacturer and a major EV maker.) https://en.wikipedia.org/wiki/BYD_Company
16. Wikipedia, “Silicon anode.” (Standard reference on silicon anodes for lithium-ion batteries.) https://en.wikipedia.org/wiki/Silicon_anode
17. Wikipedia, “Lithium.” (Standard reference on lithium, the key element in lithium-ion batteries.) https://en.wikipedia.org/wiki/Lithium
18. Wikipedia, “Cobalt.” (Standard reference on cobalt, the most ethically problematic element in lithium-ion batteries.) https://en.wikipedia.org/wiki/Cobalt
19. Wikipedia, “BYD Seagull.” (Standard reference on the BYD Seagull, an entry-level sodium-ion EV.) https://en.wikipedia.org/wiki/BYD_Seagull
20. Wikipedia, “QuantumScape.” (Standard reference on QuantumScape, a leading solid-state battery startup.) https://en.wikipedia.org/wiki/QuantumScape
21. Wikipedia, “Redox flow battery.” (Standard reference on redox flow batteries, with a section on the Dalian installation.) https://en.wikipedia.org/wiki/Redox_flow_battery
22. Wikipedia, “Pumped-storage hydroelectricity.” (Standard reference on pumped hydro, the dominant form of grid storage.) https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity
23. Wikipedia, “BloombergNEF.” (Standard reference on BloombergNEF, the leading source of battery cost data.) https://en.wikipedia.org/wiki/BloombergNEF
24. Wikipedia, “Compressed-air energy storage.” (Standard reference on CAES, a form of long-duration grid storage.) https://en.wikipedia.org/wiki/Compressed-air_energy_storage