Allotrope Energy

Engineering carbon for the next generation of batteries.

We design and make advanced carbons for energy storage: activated carbon for ultracapacitors, lithium-carbon cells and hard carbon for sodium-ion. Developed and built in our roll-to-roll labs in Basingstoke.

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One carbon platform, tuned for power, energy or both.

Batteries store a lot of energy but deliver it slowly. Ultracapacitors deliver power instantly but store little. Our carbons push both technologies further and fill the gap between them.

Power density against energy density Log-log chart. Allotrope ultracapacitors sit above typical commercial ultracapacitors at 12 to 14 watt-hours and 35 to 50 kilowatts per kilogram. Lead-acid, NiMH, sodium-ion, LTO, LFP, NMC and NCA batteries are shown in light grey, clustered at higher energy and lower power. A highlighted void, the power gap, lies between ultracapacitors and lithium-ion where almost no commercial technology exists; Allotrope lithium-carbon sits inside it at around 45 watt-hours and 12 kilowatts per kilogram. 1 10 100 1,000 100 10 1 0.1 Energy density (Wh/kg) · stores more Power density (kW/kg) · delivers faster Lead-acid NiMH LTO LFP Sodium-ion NMC NCA The power gap Typical ultracapacitors Lithium-carbon Allotrope ultracapacitor
Allotrope positions from our cell datasheets. Grey areas show typical commercial cells and are indicative.
  • The power gapBetween ultracapacitors and lithium-ion, almost nothing exists. Lithium-carbon fills it.
  • Activated carbon for ultracapacitorsTwice the energy density of today’s commercial EDLCs.
  • Lithium-carbonA battery’s energy with ultracapacitor power.
  • Hard carbon for sodium-ionLignavolt-HC1300: over 360 mAh/g and 91% first-cycle efficiency.

What we make

Carbon has long been overlooked in battery development. It is fast becoming a necessity. Each of our materials starts from the same engineering-class carbon, tailored to the job.

Rendering of porous activated carbon particles

EDLC / ultracapacitor

Activated carbon that doubles ultracapacitor energy

At the heart of every ultracapacitor is high surface area carbon. The industry has had no clear leader and little technical progress in fifteen years. Our carbon nano-sponge has doubled cell energy density, with a 60F cell demonstrated at over 12 Wh/kg, while bringing cost down.

With a time constant below 0.3 seconds, our cells deliver full power almost instantly. That is exactly what data centres need to absorb the rapid load swings of AI and GPU clusters and to bridge the moments before backup power takes over.

Energy density
12–14 Wh/kg
Time constant
<0.3 s
Power density
35–50 kW/kg
Lifetime
1,000,000 cycles
Working range
−45 to +70 °C
Capacitance
250–2,000 F
Built for data-centre power smoothing
Rendering of a lithium-carbon cell cross-section

Lithium-carbon (lithium-ion capacitor)

The missing link between batteries and ultracapacitors

Our composite anodes are so quick that only ultracapacitor carbon can keep pace on the cathode. Pair them and you get lithium-carbon: charge and discharge rates beyond 100C, passive cooling and a wide temperature range with almost no loss in performance.

First proposed in 2001, the chemistry stalled for want of the right nano-carbon. We are the first group with a commercially viable lithium-carbon technology, aimed at hybrid vehicles, micro-transport, heavy industry, ultra-fast charging devices and grid stabilisation.

Energy density
42–48 Wh/kg
Power density
11–12 kW/kg
Lifetime
100,000 cycles
Working range
−35 to +70 °C
Cell capacity
1–8 Ah
Surge current
up to 2,000 A
TRL 4, moving to TRL 5 · independently tested
Lithium-carbon compared with an ultracapacitor and high-power lithium-ion Radar chart scoring three technologies from 1 to 5 on six axes. High-power lithium-ion: power 3, energy 4, charge retention 5, temperature range 3, cycle life 2, charge rate 3; Typical ultracapacitor: power 5, energy 1, charge retention 1, temperature range 5, cycle life 5, charge rate 5; Allotrope lithium-carbon: power 5, energy 3, charge retention 5, temperature range 5, cycle life 4, charge rate 5. Power Energy Charge retention Temperature range Cycle life Charge rate

Lithium-carbon at a glance

Ultracapacitor power, with real energy behind it

Lithium-carbon keeps the power, charge rate and temperature range of an ultracapacitor, adds around seven times the energy, and holds its charge almost as well as lithium-ion. A comparable high-power lithium-ion cell stores more, but can’t charge, discharge or cycle anywhere near as hard.

  • Allotrope lithium-carbon
  • Typical ultracapacitor
  • High-power lithium-ion
View the figures
Lithium-carbonUltracapacitorLithium-ion
Power11–12 kW/kg10–20 kW/kg2–4 kW/kg
Energy42–48 Wh/kg4–7 Wh/kg70–120 Wh/kg
Charge retentionvery high, close to lithium-ionlow, self-discharges in days to weeksvery high, ≈2–3% loss per month
Temperature range−35 to +70 °C−40 to +65 °C−20 to +55 °C
Cycle life100,000 cycles500,000–1,000,000 cycles2,000–5,000 cycles
Charge rateover 100Cseconds, >300Cup to ≈10C

Scored 1–5 from typical datasheet values; the outer ring is best in class. Lithium-carbon figures from the LiC-1900 datasheet. Hover or tap a point for its value.

Built for the gap

For jobs where power matters as much as energy

A growing set of applications needs high power for seconds to minutes, thousands of times a day. Batteries meet them by being oversized and cooled; ultracapacitors by sheer weight. Lithium-carbon is sized for them from the start.

Where each technology works best, by time at full power Log timescale from 1 second to 10 hours. Ultracapacitors cover about 1 to 30 seconds, lithium-carbon about 15 seconds to 5 minutes, and lithium-ion about 6 minutes to 10 hours. Applications: AI data centres 1 second to 1 minute, hybrid cars 10 seconds to 1 minute, cranes and port equipment 15 to 90 seconds, grid frequency response 5 seconds to 15 minutes, fast-charging micro-mobility 3 to 6 minutes. Most sit inside the lithium-carbon range. The power gap 1 s10 s1 min10 min1 h10 h Ultracapacitor Lithium-carbon Lithium-ion Applications AI data centres Hybrid cars Cranes and port equipment Grid frequency response Fast-charging micro-mobility
Time at full power, log scale. Ranges are indicative; lithium-carbon spans its surge and sustained ratings.
  • Use the whole tankHybrid lithium-ion packs typically cycle within a narrow state-of-charge window to protect their life, so they carry energy they never use. Lithium-carbon can use almost its full window for 100,000 cycles.
  • No chillersLittle heat at 100C-class rates means passive cooling, removing pumps, plates and the energy they consume.
  • Works from coldFull performance from −35 °C, where lithium-ion has to restrict fast charging to avoid damage.
  • A fraction of the weightAround a ninth of the cell mass of an ultracapacitor system storing the same energy.
Worked example: lithium-carbon in a hybrid car

A 40 kW hybrid car pack in 12.6 kg of cells

The brief: 500 Wh of accessible energy and 40 kW of charge and discharge power, using cells at 42 Wh/kg and 60 Wh/L. Here’s how a lithium-carbon pack meets it. Show detailsHide details
  1. Energy500 Wh accessible, plus a 5% reserve for balancing and cold starts: 528 Wh installed.
  2. CellsEach LiC-1900-2Ah cell stores about 4.4 Wh at a 2.2 V average, so the pack needs 120 cells.
  3. VoltageAll 120 in series gives 180–336 V, 264 V nominal, a natural fit for a hybrid inverter.
  4. Current40 kW draws 152 A at nominal voltage and 222 A at the bottom of charge, well inside the cell’s 500 A surge rating.
  5. Size and heatAt 42 Wh/kg and 60 Wh/L the cells weigh 12.6 kg and take 8.8 L. Little heat at these rates means passive cooling is enough.
Configuration
120S1P 8 × 15
Pack voltage
180–336 V
Current at 40 kW
152–222 A
Cells
12.6 kg · 8.8 L
Pack, estimated
≈19 kg
Lifetime
100,000 cycles

For comparison, storing the same 500 Wh in today’s commercial ultracapacitors, at around 6 Wh/kg with roughly three-quarters usable, would take about 110 kg of cells.

Discuss a pack for your vehicle

Electrode preparation inside a glovebox in the Allotrope lab

Hard carbon anode for sodium-ion

Lignavolt-HC1300: sodium-ion, without lithium’s compromises

The battery industry is diversifying away from lithium. Sodium-ion is lithium-ion’s close relative, without the same exposure to cost, safety, supply chain or temperature problems, and its performance rests on the hard carbon in the anode.

Lignavolt-HC1300 is our hard carbon anode, made from a high-purity precursor. It pairs high first-cycle efficiency with long-term structural stability, matching leading global suppliers on performance while offering a more secure supply chain.

Reversible capacity
>360 mAh/g
First-cycle efficiency
>91 %
Capacity retention
>80 % @ 2,000 cycles
Rate capability
95 % @ 1C
Plateau capacity
66 %
Carbon purity
>99.7 %

Target specifications for developmental material, measured in half-cell vs Na/Na⁺ at 25 °C. Qualification samples available under NDA.

Download the Lignavolt-HC1300 data sheet PDF, 360 KB

Design exercise: sodium-ion

A high-energy sodium-ion cell on Lignavolt-HC1300

We paired our hard carbon with an O3 layered-oxide cathode, the highest-energy sodium-ion cathode in commercial use, and modelled a 50 Ah pouch cell around it. Show detailsHide details
C/51C
Modelled discharge voltage of the concept sodium-ion cell Cell voltage against capacity for a 50 Ah cell. At C/5 the voltage starts at 4.0 V, slopes gently through about 3.4 V at 15 Ah and 3.1 V at 28 Ah, then falls to the 1.5 V cut-off at 50 Ah, for an average of 3.1 V. At 1C the curve sits about 0.1 V lower and reaches the cut-off at about 47.7 Ah, 95% of the C/5 capacity. 1.52.02.53.03.54.001020304050 Capacity (Ah) Cell voltage (V) Nominal 3.1 V C/5 1C
Modelled discharge at 25 °C. A concept cell built from the HC1300 data sheet and typical layered-oxide cathode data, not a product.
Concept cell specification
FormatPouch, 50 Ah
ChemistryO3 layered oxide / Lignavolt-HC1300
Nominal voltage3.1 V
Voltage window1.5–4.0 V
Energy154 Wh
Specific energy≈184 Wh/kg
Energy density≈345 Wh/L
Mass≈0.83 kg
Dimensions≈325 × 100 × 13.6 mm
Rate capability95% of capacity at 1C
Cycle life>2,000 cycles to 80% (projected)
Current collectorsAluminium on both electrodes, so cells can ship at 0 V

Assumes 145 mAh/g cathode in the full cell, N/P ratio 1.1 and 3 mAh/cm² loading. HC1300’s 91% first-cycle efficiency closely matches the cathode’s, so little sodium is lost on formation.

Where it’s used

Applications our partners are developing and evaluating today.

  • Data centresSmoothing the fast load swings of AI and GPU clusters, and bridging to backup power.Ultracapacitor
  • Hybrid and off-highway vehiclesHigh-power energy recovery and boost in demanding duty cycles.Lithium-carbon
  • Micro-mobilityUltra-fast charging for mopeds, delivery vehicles and wheelchairs.Lithium-carbon
  • Grid stabilisationRapid response with very long cycle life.Ultracapacitor · Lithium-carbon
  • Stationary and EV storageA lower-cost, lithium-free anode for sodium-ion cells.Hard carbon

From lab to line

In 2022, one of the world’s largest natural raw-material suppliers commissioned us to bridge the gap between their feedstock and the battery sector. The brief was simple: turn it into the most advanced battery carbons available.

  1. 2020–22
    • $0.75m pre-seed raise; core technology completed
    • Commissioned by a global raw-material supplier
  2. 2023–24
    • $1.8m seed investment
    • Prototype production line installed
    • Lithium-carbon demonstrated
  3. 2025
    • Carbon nano-sponge doubles ultracapacitor energy density
    • Composite electrode co-developed with a partner
  4. 2026
    • Lithium-carbon developed for an off-highway vehicle
    • End users reviewing cell performance
TRL 4 → TRL 520-layer pouch cells, scaling to industrial cell formats
Independently verifiedCells tested by an independent third party
Simple to scaleClass-leading performance and cost on a roll-to-roll process

About Allotrope

Allotrope Energy is a battery materials development group in the South East of England. Our innovation is a new generation of engineering-class carbon.

Carbon is a powerful ally in next-generation battery technology. Historically overlooked, it is increasingly a necessity in advanced battery development, and we intend to stay a step ahead.

Our full-stack, roll-to-roll labs take materials from batch development through to prototype cells under one roof, so partners can see results in real cells, not just powders.

  • Guided by entrepreneurs with 8-figure exits and 9-figure IPOs
  • Backed by an investment group with business and commercial expertise
  • PhD scientists, advised by world-renowned experts in their fields
  • Technology proven and independently verified
The Allotrope Energy team in lab coats in the Basingstoke laboratory
The Allotrope team at our Basingstoke labs
Allotrope's roll-to-roll development laboratory with coating and cell assembly equipment

Media

Our announcements, what our partners have said about working with us, and coverage of our technology in the press.

Press releases

From our partners

In the press

Downloads

Arrange a chat

Tell us what you’re building and what it needs to do. Whether you’re a start-up or a global manufacturer, working with us follows the same simple path.

  1. TalkA short call about your application and targets.
  2. EvaluateSamples and data under NDA for your own testing.
  3. DevelopJoint development to tune the carbon or cell to your needs.
  4. ScaleSupply agreements as you move towards production.

info@allotrope.energy

+44 (0)1483 355 009

Hatch Industrial Park
Basingstoke RG24 7NG
United Kingdom

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