Specifications

Each Ultium pouch cell measures approximately 23 by 4 by 0.4 in (584 by 102 by 10 mm) and weighs 3.0 lb (1.36 kg), capable of storing 0.37 kWh;^[23] the nominal voltage is 3.7 V and it is rated at 103 Ah. The gravimetric energy density of each cell is 127 Wh/lb (280 Wh/kg); the corresponding volumetric energy density is 10.4 Wh/in³ (630 Wh/L). It has a 10-second gravimetric power density of 952 W/kg.^[24] For example, the total weight of the 24-module, 576-cell battery for the Hummer EV, with 212.7 kWh usable storage capacity, is 2,923 lb (1,326 kg).^[25] Pouches may be oriented horizontally or vertically, affording packaging flexibility.^[23]

Ultium features a wireless battery management system (wBMS), the first such architecture from any automaker.^[26] The wBMS was developed in partnership with Analog Devices and contributes to reduced battery costs, as it requires 90% less wiring and reduces volume by 15%.^[27]

In late January 2023, it was reported that GM was considering switching to batteries in a cylindrical cell format. This move would reduce volumetric energy density, but could reduce production time and costs.^[28]

Assembly

GM announced that cells can be composed to modules in various configurations and showcased three scenarios:^[29]

• 24 cells vertically stacked, or
• 20 cells: 10+10 cells next to each other, each pile horizontally stacked (to reduce module width), or
• 12 cells: 6+6 cells next to each other, each pile horizontally stacked (to reduce module width and height).

This way, multiple module sizes are possible, which could be mixed and matched for a certain application and platform.

In case 24 cells are combined into a module, and a battery pack is made from 6 to 24 equal modules, then 144 to 576 cells are combined into a pack with a capacity ranging from 50 to 200 kWh.^[23] GM claims that they can survive repeated DC fast charging.^[23]

For the GMC Hummer EV, there are two layers. At each layer, 12 modules are wired in series, creating a 400 V, 100 kWh battery layer; these two layers are then stacked and wired in parallel, yielding 200 kWh storage capacity for electric motors at the 400V level.^[23] For charging at 800V DC fast charging stations however, the two layers can be temporarily switched to be wired in series, allowing for DC fast charging at up to 800 V and 350 kW.^[23]

Cost

In 2010, the cost of the 16 kWh battery in the Chevrolet Volt was estimated at US$1,000 (equivalent to $1,300 in 2022) per kilowatt-hour.^[23] With Ultium, GM estimates the cost will be reduced by 90% to approximately $100/kWh.^[23] This also is a significant reduction compared to the 60 kWh battery in the Chevrolet Bolt EV, which was priced at approximately $262/kWh in 2017,^[30] although GM had negotiated a significantly lower price of $145/kWh from its supplier, LG Chem.^[31] Part of the cost reduction results from the novel chemistry, which has 70% less cobalt than the Bolt's battery.^[23] In addition, labor costs are reduced because the wiring in each battery pack has been reduced by 88% compared to the Bolt due to the wireless battery management system.^[32]

Production

Four production facilities were planned as of 2021;^[33] they have since been announced as:

• Ultium Cells LLC – Lordstown, Ohio, USA (Opened Sept. 2022,^[34] 35GWh per year capacity)^[35]
• Ultium Cells LLC – Spring Hill, Tennessee, USA (Opening late 2023, 50GWh per year capacity)^[36][37]
• Ultium Cells LLC – Lansing, Michigan, USA (Opening late-2024, 50GWh per year capacity)^[38]
• GM/Samsung SDI joint venture – New Carlisle, Indiana, USA (Opening 2026, >30GWh per year capacity).^[39][40]

GM also opened an Ultium Center factory in October 2021 in Shanghai, which produces batteries and traction motors for EVs produced and sold in China.^[41] In 2022, the United States Department of Energy (DOE) provided a $2.5 billion loan to Ultium Cells to assist in the construction of the three announced plants in the US. It is the first loan from DOE to a battery cell producer under the DOE's Advanced Technology Vehicles Manufacturing program.^[18]

In January 2023, GM and LG paused plans to build the fourth battery plant in the United States after having selected the Indiana site the previous August,^[42] with GM seeking a new joint venture partner.^[43] Later that year, Samsung SDI announced it was entering a joint venture with GM, and the fourth plant would proceed at the Indiana site.^[44] Lower than expected Ultium battery cell production caused GM to idle production of BrightDrop Zevo vans in July 2023.^[45]