Si anodes with nanotubes: going beyond 300 Wh/kg and 800 Wh/l

Silicon is the key to energy density. Why?

Material with the highest energy density

In order for EV to have higher range, it’s battery should be able to store enough energy and at the same time not weight too much/take too much space – high energy density is required.

The cherished goal in the industry – go beyond 300 Wh/kg and 800 Wh/l. But the best battery cells which are on the market today have 260 Wh/kg and 700 Wh/l (21700 type). Substantial improvement is required.

In order to reach these energy density goals and go beyond them it is necessary to use anode and cathode active materials in the battery cell with the highest energy densities.

For cathode – theses are high-nickel content materials such as NCA, NCM 811, NCM 622 and etc. For anode – silicon is the the best, if not the only, option today (and silicon-based materials, such as SiO and SiOx).

Silicon can store more than 10 times higher amount of energy than graphite, which was traditionally used as an anode material: 4200 mAh/g vs 370 mAh/g. So, switching from graphite anodes to silicon-anodes would boost the battery energy density dramatically!

Every lithium-ion battery maker would have been using silicon instead of graphite in their battery cell design, but there is a fundamental and unresolved problem of silicon.

Fundamental problem of silicon

During battery’s charging and discharging silicon substantially expands in volume (up to 300%) what leads to its cracking. Cracks in silicon cause to the loss of contact between silicon anode material particles. As a result, the battery with silicon gets out of service very fast.

This problem makes it not possible to use silicon, the best material in terms of energy density, in the recipes of the modern Li-ion batteries.

TUBALL graphene nanotubes – the key to silicon

TUBALL graphene nanotubes (or single wall carbon nanotubes) solve the key and fundamental problem of silicon-based anodes. Thanks to their unmatched conductivity, high strength, flexibility, record length-to-diameter ratio and ability to form well-developed networks inside the materials at low dosages – TUBALL graphene nanotubes, when introduced to silicon-based anode, cover the surface of silicon particles and create highly conductive and durable connections between them.

These connections are so dense, long, conductive and strong that even when the volume expansion of silicon-anode particles happen and they start to crack, the particles stay well-connected to each other with TUBALL graphene nanotubes. This keeps the anode from going out of service – it has perfect cycle life, what is enough to meet even most strict EV manufacturers requirements.

Working principle

Due to their high conductivity, flexibility and a record length-to-diameter ratio, a tiny quantity of graphene nanotubes can perfectly cover the surface of the electrode and facilitates its unmatched conductivity.

How do nanotubes work inside an electrode?

As of today, TUBALL™ is the only efficient solution that can solve the key problem of silicon anodes.

TUBALL™ networks solve the key problem of silicon-based anodes and substantially increase their cycle life up to 4x. TUBALL™ batteries with high silicon content can meet strict EV/Electronics industry requirements on cycle life. 

Today, silicon anodes = TUBALL™-based anodes

The usage of TUBALL™ in high-energy silicon anodes becomes the industry standard

Leading Li-ion manufacturers have proven that TUBALL™ nanotubes make it possible today to create anodes with 20% SiO inside and that have 600 mAh/g of capacity and 1500 cycles of service life. 

When utilizing such high-silicon-content anodes in battery designs, record-breaking battery energy densities can now be achieved: 300 Wh/kg and 800 Wh/l.


Results obtained by the OCSiAl R&D team have proven that it’s possible to increase the SiO content in anodes to 90%, which will result in energy densities of 350 Wh/kg and 1350 Wh/l.

E-nable energy

TUBALL™ BATT – a ready-to-use product for application in silicon-based anodes.

TUBALL™ BATT H2O is the first ready-to-use TUBALL™ nanotube-based solution that efficiently solves the key problem of Si/C anodes. TUBALL™ graphene nanotubes enable unmatched conductivity for Si/C anodes starting from just 0.05%. When added to Si/C anodes, the ultra-fine and stable graphene nanotubes in TUBALL™ BATT H2O fully cover and electrically connect the Si/C anode particles during the charge–discharge process of Li-ion batteries, even during the harshest cycling conditions required by EV manufacturers.

For more details on TUBALL™ BATT, click the product card below or contact us.

Related products

Water dispersion of single wall carbon nanotubes with the addition of dispersing agent. Used as a conductive additive for lithium-ion batteries


Energy Storage



Carrier Media

Water, PVP, CMC, PAA, other


Related videos

How do nanotubes work inside an electrode?

Batteries e-nabled by SWCNTs: present and future (Andrey Senyut, OCSiAl Energy)

Contact us to discuss your project specifications or to request a sample


Scientific validation

  • Anode

    Silicon Single Walled Carbon Nanotube-Embedded Pitch-Based Carbon Spheres Prepared by a Spray Process with Modified Antisolvent Precipitation for Lithium Ion Batteries

    The pitch-derived soft carbon and SWCNTs provided an excellent conductivity, and the porous structure of the composite accommodated the stress produced by the Si expansion.

  • Anode

    All-Nanomat Lithium-Ion Batteries: A New Cell Architecture Platform for Ultrahigh Energy Density and Mechanical Flexibility

    The all‐nanomat full cell shows exceptional improvement in battery energy density – 479 Wh/kg battery, and Si-anode capacity – 1166 mAh/g.

  • Anode & Cathode

    High areal capacity battery electrodes enabled by segregated nanotube networks

    High thickness and specific capacity leads to areal capacities of up to 45 and 30 mAh cm−2 for anodes and cathodes, respectively. Combining optimized composite anodes and cathodes yields full cells with state-of-the-art areal capacities (29 mAh cm−2) and specific/volumetric energies (480 Wh kg−1 and 1,600 Wh l−1).

  • Anode

    Self-transforming stainless-steel into the next generation anode material for lithium ion batteries

    Areal capacities greater than 10 mAh/cm2 and volumetric capacities greater than 1400 mAh/cm3 can be achieved.

  • Anode

    Optimization of Graphite–SiO blend electrodes for lithium-ion batteries: Stable cycling enabled by single-walled carbon nanotube conductive additive

    The use of SWCNT conductive additive enables graphite-free SiO electrodes with 74% higher volumetric energy and superior full-cell cycling compared to graphite electrodes.

  • Anode

    Comparative Characterization of Silicon Alloy Anodes, Containing Single-Wall or Multi-Wall Carbon Nanotubes

    The best results overall are obtained with 0.5%wt SWCNT added to the active powder, which produced 800mAh/g after 250 cycles.