Nyobolt is a UK-based startup that develops lithium ion batteries to reduce charging times from hours to minutes. Its ultrafast charging lithium battery has a high power density by using innovative niobium-containing metal oxide anode materials. Is has raised $84M funding to develop high power, fast charging lithium battery technology.
Challenges: fast charging lithium battery
Lithium ion batteries are typically designed for optimal performance between 15 and 40 ºC. The materials used for the positive and negative electrodes and the lithium ion-containing electrolyte are the primary limiting factors for this operation. Under such optimal conditions, battery performance properties such as specific energy, specific power, cycle life, shelf life, and safety are maximized.
When such battery powered devices are used in high power regimes, such as rapid acceleration in an electrical vehicle (EV) or fast charging mobile phone batteries (charging the battery completely in less than one hour or partial charging greater than 80% of the battery capacity in 30 minutes or less), the temperature rises rapidly due to the heat generation from high currents (ohmic losses), thereby limiting the batteries ability to deliver sustained power or accept more charge.
Overheating the battery results in catastrophic failures due to thermal runaways, fires, and explosions. To prevent rapid changes in temperature, battery management systems that control the charging and discharging of lithium ion batteries shutdown the device operation.
To overcome this limitation, bulky thermal management systems are used to keep the operation temperature of the batteries within the optimal temperature. The weight of these systems typically reduces the range of EVs by 40-50%.
In addition, temperatures of 45 ºC or higher have an effect of reducing the cycle life of the cell due to the degradation of the interfacial layer between the electrode material and the electrolyte, called the solid electrolyte interface (SEI). This SEI layer, which is formed on the anode material surface, is responsible for the stable operation of a lithium ion battery, and the upper limit of 45 ºC exists because, at higher temperatures, the SEI layer tends to decompose, resulting in a drastic fade in cell capacity.
A similar reduction in the range of an EV also occurs in a low temperature environment, such as 10 ºC or below. In particular, use of EVs in freezing conditions causes a serious reduction in range. At low temperatures, chemical reactions within the battery proceed more slowly, and in freezing temperatures, lithium plating can occur on the surface of graphite anode.
In summary, EVs require lithium-ion batteries that can operate at high rates and wide temperature windows to improve performance, driving range, faster charging, and safety. Developing batteries that can meet these requirements is essential for the widespread adoption of EVs and the transition to a more sustainable transportation system.
Nyobolt Technology
Nyobolt develops lithium ion battery technologies that achieve record-breaking ultrafast charging, high power density, and wide range of operation temperatures based on the innovative niobium-containing metal oxide anode materials.
The structure of Nyobolt’s battery cell
The diagram below depicts the structure of a Nyobolt’s lithium ion battery cell.
The cell comprises an anode, a cathode, a solid porous membrane to separate the two electrodes, and a liquid electrolyte filled in the cell.
- Anode
The anode comprises active materials (90 wt%), polymer binders (5 wt%), and nanoscale conductive carbon additives (5 wt%). The anode has 8-10 mg cm⁻² loading of active materials.
The active materials are Nb₁₆W₅O₅₅ or Nb₁₈W₁₆O₉₃ micro particles (3 – 10 microns primary). The lithium storage performance of Nb₁₆W₅O₅₅ or Nb₁₈W₁₆O₉₃ exceeds that of nanostructured versions of Li₄Ti₅O₁₂, TiO₂(B), and T-Nb₂O₅. Nb₁₆W₅O₅₅ or Nb₁₈W₁₆O₉₃ has a high density of the crystal structure and the high tap density of bulk compared with nanomaterials, which leads to exceptionally high volumetric performance.
The polymer binders improve adhesion of the active materials to a current collector plate (aluminum and copper). Typical binders are PVDF, PTFE, CMC, PAA, PMMA, and PEO.
The conductive carbon additives improve the conductivity. The conductive carbon additives can be carbon black, graphite, nanoparticulate carbon powder, carbon fiber, carbon nanotubes, Ketjen black or Super P carbon, or hard or soft amorphous carbon.
- Cathode
The cathode comprises active materials (90 wt%), polymer binders (5 wt%), and nanoscale conductive carbon additives (5 wt%). The cathode has 8-10 mg cm⁻² loading of active materials.
Suitable cathode active materials are lithium-containing or lithium-intercalated materials, such as lithium nickel manganese cobalt oxide (NMC, e.g., LiNiₘCoₙMnₖO₂), lithium vanadium fluorophosphate (LiVPO₄F), lithium nickel cobalt aluminum oxide (NCA, LiNiCoAIO₂), and lithium iron phosphate (LFP, LiFePO₄).
The polymer binders improve adhesion of the active materials to a current collector plate (aluminum and copper). Typical binders are PVDF, PTFE, CMC, PAA, PMMA, and PEO.
The conductive carbon additives improve the conductivity. The conductive carbon additives can be carbon black, graphite, nanoparticulate carbon powder, carbon fiber, carbon nanotubes, Ketjen black or Super P carbon, or hard or soft amorphous carbon.
- Separator
The solid porous membrane may comprise a polymer (e.g., polyethylene, polypropylene, or copolymer thereof) or an inorganic material, such as a transition metal oxide (e.g., titania or zirconia) or main group metal oxide, such as silicon oxide, which can be in the form of glass fiber.
- Electrolyte
The electrolyte comprises lithium salts, organic solvents, and additives.
The lithium salts can be LiTFSI, (bis(trifluoromethane)sulfonimide lithium salt, LiPF₆, LiBF₄, LiCIO₄, or lithium bis(oxalato) borate (LiBOB).
The organic solvents dissolve lithium ions. Suitable solvents include propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), chloroethylene carbonate, fluoroethylene carbonate, trifluoromethyl propylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), and ethyl propyl carbonate (EPC).
Suitable solvents also include methyl sulfone, ethyl methyl sulfone, methyl phenyl sulfone, methyl isopropyl sulfone (MiPS), propyl sulfone, butyl sulfone, tetramethylene sulfone (sulfolane), phenyl vinyl sulfone, allyl methyl sulfone, methyl vinyl sulfone, divinyl sulfone (vinyl sulfone), diphenyl sulfone (phenyl sulfone), dibenzyl sulfone (benzyl sulfone), vinylene sulfone, butadiene sulfone, 4-methoxyphenyl methyl sulfone, 4- chlorophenyl methyl sulfone, 2-chlorophenyl methyl sulfone, 3,4-dichlorophenyl methyl sulfone, 4-(methylsulfonyl)toluene, 2-(methylsulfonyl) ethanol, 4-bromophenyl methyl sulfone, 2-bromophenyl methyl sulfone, 4-fluorophenyl methyl sulfone, 2-fluorophenyl methyl sulfone, and 4-aminophenyl methyl sulfone.
Suitable solvents also include silicon-containing solvents, such as hexamethyldisiloxane (HMDS), 1,3-divinyltetramethyldisiloxane, polysiloxane-polyoxyalkylene derivatives, methoxytrimethyIsilane, ethoxytrimethyIsilane, dimethoxydimethylsilane, methyltrimethoxysilane, and 2-(ethoxy)ethoxytrimethylsilane.
Typically, an additive may be included in the electrolyte to improve performance. Additives can be vinylene carbonate (VC), vinyl ethylene carbonate, allyl ethyl carbonate, t-butylene carbonate, vinyl acetate, divinyl adipate, acrylic acid nitrile, 2-vinyl pyridine, maleic anhydride, methyl cinnamate, ethylene carbonate, halogenated ethylene carbonate, a-bromo-y- butyrolactone, methyl chloroformate, 1,3-propanesultone, ethylene sulfite (ES), propylene sulfite (PS), and 12-crown-4 ether.
The performance of Nyobolt’s battery
The performance of the battery was demonstrated. The anode active material is Nb₁₆W₅O₅₅ (NWO). The cathode active material is LiFePO₄ (LFP).
Both electrodes comprise 90 wt% active material, 5 wt% super P (Imerys) and 5 wt% polyvinylidene fluoride (PVdF from Kynar) binder.
The electrodes loadings were 8.4 – 8.7 mg/cm² of LFP and 8.8 – 9.4 mg/cm² of NWO.
The electrolyte is composed of 1.0 M lithium hexafluorophosphate (LiPF₆) in ethylene carbonate (EC): dimethyl carbonate (DMC) (1 :1 v/v).
A polyethylene separator (Toray) was used.
Variable-temperature cycling of NWO/LFP cells was conducted for 1,000 cycles at 5C rate. As shown in the figure below, at temperatures of 10, 25, and 60 ºC, 6.9%, 7.9% and 18.1% capacity loss was observed over 1,000 cycles, respectively.
Nyobolt Patent
- GB202218243D0 Power distribution device
- GB202201822D0 Charging device
- GB202115818D0 High-rate battery system
- GB2592341B Electrode compositions
- EP3326225B1 Lithium-oxygen battery
Nyobolt Products
Nyobolt plans to build its first material manufacturing plant in the UK in 2023 and expand its cell engineering facility in Boston, the US.
Nyobolt Funding
Nyobolt has raised a total of $83.6M in funding over 5 rounds, including a Grant round, a Seed round, a Series A round, a Venture-Series Unknown round, and a Series B round. Their latest funding was raised on Jan 30, 2023 from a Grant round.
Nyobolt Investors
Nyobolt is funded by 5 investors, including Parkwalk Advisors, IQ Capital, University of Cambridge Enterprise, H.C. Starck, and UK Research and Innovation. UK Research and Innovation and IQ Capital are the most recent investors.
Nyobolt Founder
Sai Shivareddy, Clare Grey, and Kent Griffith are Co-Founders.
Nyobolt CEO
Sai Shivareddy is CEO.
Nyobolt Board Member and Advisor
Sai Shivaredd, Marc Doyle, Martin Frost CBE, and Richard Green are Board Members.
