Solid-State Batteries: Wolfpacks of Small UUVs Will Dominate the Seas
by Patricia Marins
UUVs are currently the most dangerous threat to submarines and military surface ships. Their development is accelerating rapidly, and I would argue that the smallest ones are the most dangerous.
This week, the first solid-state battery ready for mass production was announced, with an energy density of 400 Wh/kg. By 2028, several companies are promising to reach 600 Wh/kg , roughly 3–4 times the density of today’s lithium-ion batteries.
This will completely transform naval warfare.
It not only renders conventional diesel-electric submarines obsolete but also creates an entirely new category of UUVs: small, mini, and extremely fast.
I’m talking about UUVs in the 250–350 kg weight, capable of sprint speeds of 45–50 knots.
They would carry a compact 50 kg warhead using modern explosives, including CL-20-based mixtures, inside a fuselage largely composed of solid-state battery cells, supplemented by a small 2.5 kVA gasoline generator with a snorkel for recharging.
These UUVs could be air-dropped, ships, submarines, from aircraft or larger drones, and operate in Wolfpack, sprinting up to 35 km to engage targets.
If the target pulls out of range, the onboard AI calculates that interception is no longer feasible and switches to recharge mode, surfacing discreetly, running the generator, and continuing to track the target via periscope or mast-mounted sensors. It analyzes surface images, estimates target course and speed, and calculates the exact energy needed for a new high-speed intercept, also getting data from satellites or drones, composing a versatile kill web.
A true high-tech wolfpack: persistent, autonomous, and capable of engaging both surface ships and submerged submarines (by forcing them to surface or detecting them when they snorkel).
Warhead design is evolving toward combined shaped charge + blast configurations: an initial shaped charge penetrates the outer hull or Kevlar spall liners (creating a breach and injecting energy), followed immediately by the main high-explosive blast that causes flooding, shock damage to equipment, and internal compartment failure.
This mirrors the mechanism of modern lightweight torpedoes.
A UUV carrying just 50 kg of advanced explosive in such a warhead would be capable of breaching the pressure hull of a Virginia-class submarine or the hull of an Arleigh Burke-class or Type 055 destroyers, causing serious flooding and likely achieving at least a mission kill. In successive impacts from a wolfpack, the damage would be catastrophic, comparable to that inflicted by an Mk 54 or MU90 torpedo.
Another key development is the refinement of UUV AI to prioritize initial strikes against propulsion systems (shafts, propellers, reduction gears, or waterjets), maximizing the chance of immobilizing the target early.
These are fully autonomous units that can loiter for weeks, hunting targets, making independent decisions, and even receiving software updates while recharging on the surface.
They fit into a broader ecosystem of UUVs, primarily propeller-driven, torpedo-shaped vehicles weighing 250–350 kg with warheads of 50–100 kg, but the range of designs and capabilities is expanding fast.
Their cost is orders of magnitude lower than any manned ship or submarine, and effective countermeasures do not yet exist. We are talking about a technology that could put billions of dollars in naval investments at risk.
The trend is clear: UUVs will continue to get cheaper, faster, longer-ranging, and smarter, while traditional platforms (surface ships and submarines) only become more expensive and vulnerable.
These wolfpacks will be supported and coordinated by drones, satellites, and motherships.
Just as drones have reshaped land warfare, UUV swarms are doing the same at sea.
