Factorial Energy ($240M for solid-state lithium battery)

Factorial Energy develops solid-state lithium ion batteries that are stable, safe, and have a  high energy density using its innovative solid polymer electrolytes. Factorial Energy’s batteries have a 20% to 50% higher energy density than conventional lithium-ion batteries, which directly translates to a greater driving range of EVs. The company has raised $240 million to accelerate their research and development efforts.

Challenges: lithium battery storage

The increasing demand for electric vehicles (EVs) as a means of reducing carbon emissions has brought to light one of the biggest challenges facing the industry: lithium-ion batteries. These batteries are essential for EVs as they store and release electrical energy, making them a key component of the vehicle’s powertrain.

Solid-state lithium-ion batteries are a type of next-generation battery technology that offers several advantages over traditional lithium-ion batteries for EVs. Solid-state batteries replace the liquid electrolyte used in traditional lithium-ion batteries with a solid-state electrolyte, which can provide higher energy density, faster charging times, longer cycle life, and improved safety.

Here are some of the potential advantages of solid-state lithium-ion batteries for EVs:

  • Higher energy density: Solid-state batteries can offer a higher energy density, which stores more energy in the same amount of space, resulting in longer driving ranges for EVs and lighter battery packs, thereby enhancing vehicle efficiency and reducing costs.
  • Faster charging times: Solid-state batteries can withstand higher charging rates without overheating or degrading than traditional lithium-ion batteries. This could reduce charging times for EVs, making them more practical and convenient for daily use.
  • Longer cycle life: Solid-state batteries can have a longer cycle life than traditional lithium-ion batteries because they degrade less over time. This extends the lifespan of EV batteries and reduces the need for costly replacements.
  • Improved safety: Solid-state batteries are less flammable than traditional lithium-ion batteries that use a liquid electrolyte which can catch fire if the battery is damaged or overheats. Solid-state batteries make EVs safer and reduce the risk of battery-related fires or explosions.

Although solid-state lithium-ion batteries have several advantages over traditional lithium-ion batteries, there are still several technical and manufacturing challenges that need to be overcome before they can be commercialized for use in EVs:

  • Electrolyte conductivity: Solid-state electrolytes are less conductive than liquid electrolytes. This limits the rate at which ions can move between the cathode and anode, thereby affecting the battery’s performance.
  • Electrode-electrolyte interface: Solid-state batteries have a less stable electrode-electrolyte interface than  traditional lithium-ion batteries, which affects the battery’s energy density, cycle life, and safety.
  • Manufacturing scalability: Solid-state battery production processes are more complex and expensive than traditional lithium-ion battery manufacturing. It is challenging to scale up the production of solid-state batteries to meet the demands of the automotive industry.
  • Cost: Solid-state batteries are currently more expensive to manufacture than traditional lithium-ion batteries. Reducing the cost of manufacturing solid-state batteries is crucial for making them commercially viable for use in EVs.

Despite these challenges, several companies, such as QuantumScape, Solid Power, and 24M Technologies, are actively developing and improving solid-state lithium-ion batteries. The technical and manufacturing challenges of solid-state batteries are expected to be addressed, and they can become a viable option for powering EVs in the future.

Factorial Energy Technology

Factorial Energy has developed solid-state lithium ion batteries that are stable, safe, and have high energy density using its innovative solid polymer electrolytes. The solid-state batteries have a 20% to 50% higher energy density than standard lithium-ion batteries, which directly translates to a greater driving range of EVs. The solid-state batteries can be produced by using the existing mature production lines of traditional lithium-ion batteries, thereby reducing the production cost.

Factorial Energy solid battery

The diagram below depicts a typical structure of Factorial Energy’s solid-state lithium-ion battery.

The structure of Factorial Energy’s solid-state lithium-ion battery.
The structure of Factorial Energy’s solid-state lithium-ion battery.

The battery comprises an anode, a cathode, a separator (optional) that separates the two electrodes, and solid electrolyte filled in the cell.

  • Anode

Factorial Energy’s solid-state batteries can use lithium metal (Li) or graphite as anode materials.

Lithium metal (Li) is a promising anode material due to its high theoretical specific capacity (3,860 mA h g⁻¹) and low reduction potential (−3.04 V versus the standard hydrogen electrode). The high energy density of lithium metal anode makes lithium-ion batteries more compact and lightweight. Lithium metal anodes have a higher charging rate compared to other types of electrodes. This means that the battery can be charged faster, which is useful for devices that require rapid recharging.

Graphite is a common anode material in lithium-ion batteries. Graphite also has a relatively high theoretical capacity of 372 mA h g⁻¹, allowing it to store a large amount of energy in a small volume. This makes it an excellent choice for applications requiring high energy density, such as electric vehicles and portable electronics.

Graphite anode material has additional advantages. Graphite is a very stable material. It is less prone to degradation and can withstand many charging and discharging cycles without losing its capacity. Compared to other anode materials such as silicon and tin, graphite is relatively inexpensive, making it a cost-effective choice for large-scale battery manufacturing. Graphite is a non-toxic and non-flammable material. This makes it safer to use in batteries than other materials.

  • Cathode

The cathode material for Factorial Energy’s solid-state batteries includes lithium cobalt oxide (LCO), lithium nickel manganese cobalt oxide (NMC) (e.g., LiNi1/3Co1/3Mn1/3O₂ or LiNi0.5Co0.2Mn0.3O₂), lithium nickel cobalt manganese aluminum oxide, lithium nickel cobalt aluminum oxide, lithium titanate, metallic lithium, lithium metal oxide, lithium cobalt oxide, lithium manganese oxides (LMO) (e.g., LiMn₂O₄ and LiNi0.5Mn1.5O₄), lithium iron phosphates (LFP) (e.g., LiFePO₄), LiMnPO₄, LiCoPO₄ (LCP), Li₂MMn₃O₈ (M = Fe or Co), layered Li—Ni—Co—Mn oxides (NCM), and layered Li—Ni—Co—Al oxides (NCA).

  • Solid electrolyte

The solid electrolyte comprises polymers that are crosslinked, lithium salts, and additives. The following section describes each composition’s specifics.

The solid electrolyte is formed by mixing a liquid electrolyte and a polymer precursor, then introducing the liquid mixture into a pre-assembled cell, and finally solidifying the liquid electrolyte within the cell. Solidification within the cell occurs based on cross-linking of polymer precursors in the electrolyte via an initiator.

Factorial Energy solid electrolyte

  • Polymers

Factorial Energy has developed suitable polymer precursors for the formation of solid electrolytes with a high ionic conductivity, high voltage window, and non flammability. The key feature of these polymer precursors lies in that the backbone of these polymer precursors contains urea, urethane, or carbamate moieties. Through the use of an initiator, these moieties are able to form a network of interconnected polymers, as depicted in the diagram below.

A network of interconnected polymers in solid electrolyte.
A network of interconnected polymers in solid electrolyte.

These moieties contain carbon-oxygen or nitrogen-carbon sigma bonds that are rigid, which may help the structure to resist decomposition. The moieties also contain both hydrogen bond donors and acceptors, resulting in enhanced mechanical and electrochemical properties. For example, urea linkers with rigid bonding may help to improve mechanical strength. The hydrogen bonds can facilitate the dissociation of lithium salts, resulting in improved ionic conductivity.

The following structures are examples of polymer precursors containing urea and/or carbamate functional groups:

Polymer precursors in solid electrolyte of Factorial Energy's battery (ref. US11302960B2).
Polymer precursors in solid electrolyte of Factorial Energy’s battery (ref. US11302960B2).

wherein R1 is selected from the following groups:

R1 groups of polymer precursors in solid electrolyte of Factorial Energy's battery (ref. US11302960B2).

R2, R3, R4, R5, and R6 are each independently selected from the group consisting of hydrogen, methyl, ethyl, phenyl, benzyl, acryl, epoxy ethyl, isocyanate, cyclic carbonate, lactone, lactam, and vinyl; and * indicates a point of attachment.

To facilitate polymerization of polymer precursors, the electrolyte contains a suitable initiator, such as benzoyl peroxide, 2,2′-azobisisobutyronitrile (AIBN), 4,4-azobis (4-cyanovaleric acid) (ACVA), potassium persulfate Irgacure initiator, 2,2′-azobis(2-methylpropionitrile), and ammonium persulfate. The optimal mole fraction of the initiator is between 0.001 and 0.01.

  • Lithium salts

The solid-state polymer electrolyte contains lithium salts, such as lithium bis(fluorosulfonyl)imide (LiFSI) and  lithium bis(trifluoromethane)sulfonimide (LiTFSI).

  • Additives

The solid electrolyte contains cathode protective agent LiDFOB (lithium difluoro(oxalato)borate), anode protective agent fluoroethylene carbonate, anti-oxidative agent LiBOB (lithium bis(oxalate)borate), and inorganic additives, such as Al₂O₃, SiO₂, SiOₓ, TiO₂, Li₃PS₄, and Li₁₀GeP₂S₁₂. These stabilization additives are useful for maintaining the voltage of the polymer electrolyte batteries at a minimum of 4.4 V. The amount of stabilization additives is no more than 15 wt% of the solid electrolyte.

The solid electrolyte contains a plasticizer, such as succinonitrile, ethylene carbonate, sulfolane, and trimethyl phosphate.

The solid electrolyte contains an organic carbonate additive that facilitates the formation of a less-resistive solid electrolyte interphase (SEI) and achieves a higher capacity. A small amount of organic carbonate increases ionic mobility by decreasing lithium coordination, while maintaining the inflammability of the electrolyte. Organic carbonates additives include ethylene carbonate (EC), vinylene carbonate (VC), fluoroethylene carbonate (FEC), methylene-ethylene carbonate (MEC), 1,2-dimethoxyethane carbonates (DME), and diethylene carbonate (DEC). The amount of organic carbonate in the solid electrolyte is no more than 15 wt%.

The solid electrolyte may contain an ether additive. An ether additive can be a linear polymer that increases the conductivity of the solid electrolyte. Examples of ether additives include hydrofluoroether,1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, bis(2,2,2-trifluoroethyl)ether, oligo ethylene glycol methyl ether, tetraethylene glycol dimethyl ether, bis(2,2,2-trifluoroethyl) ether, oligo ethylene glycol methyl ether, etc. The ether additive is no more than 0.3 wt%.

The solid electrolyte may further contain ionic liquids (melting point below 100 ºC). Ionic liquid electrolytes are thermally stable, less volatile, and  inflammable, improving the safety and durability of lithium-ion batteries. They have a broad electrochemical stability window, allowing the use of high-voltage electrode materials and achieving higher energy density batteries. The ionic liquid can improve the cyclability and capacity retention of lithium-ion batteries, thereby extending their lifespan.

Suitable ionic liquid include N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide ionic liquid, N-alkyl-N-methylpyrrolidinium, perfluorosulfonylimide (PFSI), N-alkyl-N-methylpyrrolidinium (PYR1A) perfluorosulfonylimide (PFSI), 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (IM12FSI), 1-Propyl-3-methylimidazolium Bis(fluorosulfonyl)imide (IM13FSI), N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (Py14TFSI), N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide (Py13FSI), and N-Butyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (Py14FSI).

The molecular structures of IM12FSI and Py13FSI are presented below:

Factorial Energy battery performance

Factorial Energy has developed and scaled up the 40 Ah solid-state lithium-ion batteries based on its solid polymer electrolyte, graphite anodes or lithium metal anodes, and standard cathode of NMC811.

The 40 Ah NMC811‖graphite cell cycles for over 1,100 cycles with approximately 95% capacity retention (4.2 to 2.8 V; C/3–C/2 rate; 25 ºC). At 60 ºC, the same cell type under identical electrochemical conditions endured about 400 cycles before falling below 80% capacity retention and lasted 500 cycles before falling below 75% capacity retention, outperforming the high-temperature cycling performance of NMC811‖graphite cells with liquid electrolytes.

However, 20 Ah NMC811‖Li metal cells are still in the early stages.

Factorial Energy Patent

  • US11302960B2 Polymer solid electrolytes, methods of making, and electrochemical cells comprising the same
  • US20210020978A1 Electrolytes for high-voltage cathode materials and other applications
  • US11450884B2 Electrolyte, anode-free rechargeable battery, method of forming anode-free rechargeable battery, battery, and method of forming battery
  • US10741837B2 Nickel-based positive electroactive materials
  • US20200274160A1 Nickel-cobalt-aluminium ternary lithium ion battery cathode material, preparation method and application thereof, and lithium ion battery
  • US11404697B2 Composition, article, method of forming article, anode-free rechargeable battery and forming method thereof, and battery
  • US20220263094A1 Electrodes for lithium-ion batteries and other applications

Factorial Energy Products

Factorial Energy has developed ground-breaking solid-state batteries that provide up to 50% longer range per charge, enhanced safety, and are cost competitive with conventional lithium-ion batteries.

The company’s proprietary FEST™ (Factorial Electrolyte System Technology) enables safe and reliable cell performance with high-capacity cathode and anode materials. FEST™’s electrolyte has been successfully scaled in 100 Ah cells, operates at room temperature, and can utilize the majority of existing lithium-ion battery manufacturing equipment.

Factorial Energy's 100 Ah battery prototype for EVs (Source Factorial Energy)
Factorial Energy’s 100 Ah battery prototype for EVs (Source Factorial Energy).

Factorial Energy’s core competence is in materials. However, the company does not intend to directly compete with companies like LG Chem and CATL, but rather forms partnerships to bring their product to the market.

Factorial Energy Funding

Factorial Energy has raised a total of $240M in funding over 3 rounds: a Series A round, a Series B round, and a Series D round. Their latest funding was raised on Jan 20, 2022 from a Series D round.

The funding types of Factorial Energy.
The funding types of Factorial Energy.
The cumulative raised funding of Factorial Energy.
The cumulative raised funding of Factorial Energy.

Factorial Energy Investor

Factorial Energy is funded by 6 investors, including Mercedes Benz, Stellantis, Kia Motors, Hyundai Motor Company, Gatemore Capital Management, and WAVE Equity Partners. Mercedes Benz and Stellantis are the most recent investors.

The cumulative raised funding of Factorial Energy.
The cumulative raised funding of Factorial Energy.

Factorial Energy Founder

Siyu Huang and Alex Yu are Founders.

Factorial Energy CEO

Siyu Huang is CEO.

Factorial Energy Board Member and Advisor

Michael Bly and Liad Meidar are Board Members.

Scroll to Top