Xing's Immersio CTP Ship Battery Claims 200 Wh/kg With No Vessel Aboard

Xing Mobility says its Immersio CTP marine battery stores about 200 Wh/kg in laboratory tests, 19 percent above the 168 Wh/kg listed for Corvus Energy's Dolphin NxtGen system. No vessel runs the pack yet, and the certification that would let a passenger ferry carry one has not been granted, according to an IEEE Spectrum report by Willie D. Jones published Nov. 11.

The gap between "twice the energy of conventional marine batteries", Xing's headline, and 19 percent is a difference of baseline. The company's comparison basis is LFP packs; the 19 percent is against a named competing system.

The ferry above is an unrelated battery-electric cable ferry in Canada, shown for scale of the vessel class. It does not use Xing's pack.

What the Immersio CTP is

Xing Mobility, of Taoyuan City, Taiwan, unveiled the cell-to-pack design at the SMM trade fair in Hamburg in September. Cylindrical 21700 cells, mainly nickel manganese cobalt or nickel cobalt aluminium, sit directly in a coolant that absorbs heat without conducting electricity. A molded composite holder grips the cells, channels the fluid and acts as the structure, which removes the metal module boxes and cold plates. Royce Hong, Xing's founder and chief executive, told IEEE Spectrum: "Everything is integrated into one piece."

Electrive's August preview of the show was blunter about the evidence. The company supplied only broad details by email and no performance data, the outlet wrote, so the energy-density and 3C continuous-discharge claims could not be checked.

The density numbers and their denominators

Xing's 200 Wh/kg includes coolant and battery management system, and it is a laboratory figure. The volumetric claim is for mass-produced packs, which is a different stage of maturity from the gravimetric one.

1. Xing Immersio CTP, high end350 Wh/L
2. Xing Immersio CTP, low end330 Wh/L
3. Corvus Dolphin NxtGen212.5 Wh/L

Source: IEEE Spectrum, Nov. 11, 2026; Xing figures are company claims for mass-produced packs

On volume, Xing's range is 55 to 65 percent above Corvus. IEEE Spectrum does not report pack capacity in kWh, weight, cost or range, so a shipowner cannot yet turn any of this into nautical miles per charge.

The fire claim and the flammable fluid

Xing's documentation says immersion cools a punctured cell from about 1,000 °C to below 100 °C within 10 seconds. Cedric Lin, a senior engineering manager at Xing, said the pack has been tested many times to IEC 62619 at TÜV and Intertek labs, but he did not share results or confirm the 10-second figure.

Paul Kohl of Georgia Tech called the figure feasible: "It's well within the realm of feasibility." He is less kind to the fluid. The coolant is flammable, and "Using a flammable liquid, of course, you're throwing away part of the advantage of the immersion battery." Nickel-rich cells also enter thermal runaway more readily than LFP, and Kohl questions whether the oil survives a decade of thermal cycling with water and salt exposure: "Ten years' reliability and no degradation is a very demanding requirement."

Certification and competitors

Xing has submitted the design to DNV for document review and is preparing physical tests. Only two vessels run on any Xing pack, and neither uses the CTP. Hong told IEEE Spectrum that smaller vessels and some cargo ships may adopt it before large passenger ferries, which need DNV approval first.

Two rivals are ahead on paper. Kreisel Electric of Austria won DNV certification for an immersion-cooled pack in 2023; its batteries power Candela's P-12 hydrofoil ferry. Wattalps of France received Bureau Veritas marine approval in January 2026 using a nonflammable fluid. IEEE Spectrum puts the global electric ship market at under $5 billion in 2025.

That is the same sorting we applied to IBM's qubit roadmap and to Agility's order book: lab figure, announced figure, then units in service. Xing is at the first rung.

What would change this read

Two results would move the assessment. A DNV approval, with test data on discharge at ship duty cycles, would make the density gap a procurement fact. A flammable-fluid incident or a fluid-degradation finding after extended thermal cycling would end the case for nickel cells in immersion. Neither exists in public yet.