Cathodes with graphene nanotubes: superior discharge rates, energy density, cycle life and safety
Demand for performance in the competitive Li-ion market
The ambitious energy density targets, faster charging, higher power, longer service life and safety requirements from the emerging giant EV industry require Li-ion battery manufacturers to select the best materials for the battery cells they produce. Only by doing that will it be possible for them to survive the competition and “stay in the game”. Performance is critical.
TUBALL™ graphene nanotubes
TUBALL™ graphene nanotubes (also known as single wall carbon nanotubes) are the most electrically conductive and strong material that can be used in the recipe of Li-ion batteries. This fact, together with their other unique properties such as high length-to-diameter ratio, flexibility and ability to create well-developed conductive and reinforcing networks inside active materials, allows TUBALL™ nanotubes to boost Li-ion batteries’ performance even at ultra-low working dosages.
This SEM image clearly shows that just 0.08% of TUBALL™ graphene nanotubes in NCM 811 active material fully covers the active material surface and connects the particles together.
Thanks to their unique intrinsic properties, graphene nanotubes outperform competitors and offer substantial Li-ion battery performance improvements in terms of discharge power, energy density and adhesion, as well as safety. Such performance improvements for Li-ion battery cathodes cannot be demonstrated by any traditional conductive additives, such as carbon black or multi wall carbon nanotubes.
Higher discharge power
Thanks to graphene nanotubes’ unmatched conductivity compared with other conductive additives, using TUBALL™ in cathodes makes it is possible to achieve fast discharge while also increasing the battery’s capacity.
Higher energy density
Less than 0.1% of TUBALL™ provides higher energy density. This concentration is lower by 10–60 times than that needed when using multi wall carbon nanotubes or carbon black as a conductive additive. In a modern EV battery pack, 5 kg of conductive carbon black can be replaced by just 100 g of TUBALL™.
Higher cathode adhesion
Nanotube networks hold the cathode material particles together, increasing the bond strength between them.
Being the most conductive material that can be used in the recipe of Li-ion batteries, even a small amount of TUBALL™ graphene nanotubes is enough to reduce internal battery cell resistance (DCR). Stable TUBALL™ networks are maintained inside the cathode material even after multiple battery charge–discharge cycles and battery storage periods, enabling the DCR to be maintained at a low level as well – after HT storage and cycling.
The lower battery DCR results in lower temperature build-up, and thus a reduced risk of a battery fire. This is a crucial safety benefit, made possible by TUBALL™ graphene nanotubes.
Performance e-nabled by TUBALL™ graphene nanotubes
To facilitate the application of graphene nanotubes in LCO, LFP, NCM-based and other types of cathodes, OCSiAl has developed the ready-to-use product TUBALL™ BATT that contains well-dispersed nanotubes in various liquid carriers and that can be simply mixed in during standard manufacturing processes.
TUBALL™ BATT features for cathodes:
Maximized energy density by enabling a higher possible content of active material
Improved safety – lower battery resistance and thus lower temperature
More power at high discharge rates
Better electrode adhesion
For anodes, TUBALL™ solves the main problem of silicon anodes – poor cycle life.
For all the details on TUBALL™ BATT for cathodes, click the product card below or contact us.
Liquid dispersion of single wall carbon nanotubes in NMP with the addition of dispersing agent. Used as a conductive additive for lithium-ion batteries
Batteries e-nabled by SWCNTs: present and future (Andrey Senyut, OCSiAl Energy)
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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).
Rational design of a high-energy LiNi0.8Co0.15Al0.05O2 cathode for Li-ion batteries
Replacing Denka black with SWCNT allows to reduce the carbon content to 0.2 wt% to further increase the energy density, and 2 wt% of PVDF was shown to benefit the cycling stability due to the mitigated PVDF-induced side reactions from its direct contact with NCA particles.
Quantifying the effect of electrical conductivity on the rate-performance of nanocomposite battery electrodes
100 μm thick electrodes with mass loadings 2 of ∼15 mg/cm2 were produced. While carbon black or graphene loadings of >10 wt % are required to reach OOP conductivities of 1 S/ m, this level can be achieved with ∼1 wt % of carbon nanotubes.
Constructing a Highly Efficient Aligned Conductive Network to Facilitate Depolarized High-Areal-Capacity Electrodes in Li-Ion Batteries
With minimum inactive components (i.e., binder and conductive agents), the proposed electrode structure delivers good cycling stability and rate capability under high areal loading (as high as 200 mg cm−2).