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Battery Technology and the Space Sector

Fri, 06 June, 2025

Battery technologies have been an important facet of space exploration since the launch of Explorer in 1958, with some form of energy storage device being used in all robotic spacecraft, either as a primary source of electrical power or for storing electrical energy.

While many satellites, for example, rely on solar panels to deliver electricity while in orbit, they use batteries to unfold the solar arrays before storing energy from the solar panels ready to be used at times of peak power demand, when the solar panels are shaded, or in the case of an emergency. Where solar panels are not suitable for use, primary batteries are used, such as non-rechargeable lithium sulphur dioxide batteries. These batteries were used on the European Space Agency’s Huygens Probe, as they could be left inactive for seven years while the probe reached Saturn before being used to effect a landing on the planet’s moon, Titan. Elsewhere, lithium-sulphuride chloride batteries were used on the Foton M3 missions, where they were able to power over 10 days of experiments on microgravity before re-entering the Earth’s atmosphere.

The Ariane 5, which pulls European spacecraft into orbit, uses batteries to power autonomous operations during the flight, including inertial navigation and guidance, engine firing and booster separation. The European Vega launcher uses three types of lithium-ion batteries, while the ESA’s Energy Storage section at ESTEC works with industry to make a range of batteries available for space sector applications.

The engines on SpaceX’s Starship are equipped with battery-powered gimbal actuators, while NASA’s Insight mission to Mars used lithium-ion batteries. The excellent temperature stability of plutonium-238 cells have led to them being proposed as a solution for lunar expeditions, and lithium-sulphur batteries are due to be tested aboard the International Space Station (ISS). These tests will include during launch, orbital operation and recovery, ahead of potential use in satellites, space suits and extravehicular activities (EVA).

Battery Types

The three main categories of battery used in the space industry are primary batteries, rechargeable batteries, and capacitors. Although fuel cells are also used in manned missions, they have not yet been used in fully robotic missions.

Primary batteries tend to be used for missions that need a single use electrical power source, lasting between minutes and days. This includes for launch vehicles, planetary probes and sample return capsules.

Rechargeable batteries are typically used alongside solar power for load levelling or to maintain electrical power during eclipses, these are also known as secondary batteries as they tend to act as a back-up.

Capacitors have been used in radioisotope-powered missions but were also used for the Pluto-New Horizons missions to deliver repeated, short duration, high-power pulses.

The types of battery that are commonly-used by the space sector include:

  • Nickel–Cadmium (NiCad): This type of battery has been used for space applications for decades. They comprise of a nickel cathode (positive electrode) and a cadmium anode (negative electrode) with potassium hydroxide acting as the electrolyte. Although they have a high discharge rate and the ability to deliver the full capacity, they are not as energy dense as alternative options. They can also be prone to overcharging and overheating due to the high charging rate. Prolonged use can also lead to holes in the insulator material that makes charging impossible without a high pulse current.
  • Nickel–Hydrogen (NiH2): These batteries have been designed specifically for use in space and are a hybrid between battery and fuel cell technology. They have positive nickel hydroxide electrodes and a negative platinum catalyst with negative hydrogen gas held in the cell case. These batteries are safe from overcharging or overdischarging and have a higher specific energy than NiCad batteries. However, they have a high self discharge rate and low volumetric density, as well as requiring high pressure storage during charging to contain the hydrogen gas.
  • Lithium-ion (Li-ion): These batteries have found uses in a range of industries, including space, where they are favoured for their long lifetime, recharging capacity and dense energy provision. Capable of working at a wide range of temperatures, they deliver short and high energy peaks without harming the cell. The cathode material can differ, offering different characteristics, while the anode is typically carbon-based. Examples include low cost lithium manganese oxide (LMO) and lithium manganese nickel (NMC) cells as well as lithium nickel cobalt aluminum oxide (NCA) and lithium iron phosphate (LFP) cells. However, lithium nickel cobalt oxide (NCO) are rarely used as they have relatively poor safety ratings. All Li-ion batteries are class 9 dangerous goods according to the United Nations (UN), so specific safety regulations need to be followed when using them.

Batteries and Space Operating Conditions

Choosing the correct type of battery for space use requires consideration of a number of factors, such as the mission’s parameters, system design specifications, the technologies in use during the mission, and the key performance criteria of the batteries themselves.

The first thing to consider for satellites is the orbit of the mission, whether Low Earth Orbit (LEO), Geosynchronous Orbit (GEO), or in Medium Earth Orbit (MEO). Each of these orbits changes the battery cycles in accordance with the seasons and the duration of eclipses experienced by the satellites. The specific energy of the battery also varies according to the mission orbit.

It is also important to understand the functions your technologies will perform, how frequently, and for how long, as these will impact your batteries’ requirements. You should also consider the launch stresses, testing procedures, and any regulatory compliance requirements ahead of launch, as well as obsolescence procedures at the end of the mission. The design specifications of your satellite, vehicle or craft also need to be considered in relation to volume, weight, and structural materials. Accompanying technology should also be compatible with the battery solutions, including sub-systems and structural components that need to interact.

These considerations will inform key performance criteria for the batteries, including capacity, voltage, power, and the physical battery cell configuration. In addition, the depth of discharge – the difference between a battery’s discharged and nominal capacity – the weight of the battery pack, and the chemical composition of the battery are also important.

Growing Demands

There is now a growing demand for new high-energy density batteries, such as lithium-sulphur batteries that offer potential weight reductions and improved reliability. These batteries are up to 40% lighter than lithium-ion and 60% lighter than lithium iron phosphate (LFP) batteries, while the increased density also promises to increase the amount of time astronauts can engage in extravehicular activity from around 4 or 5 hours to 8 hours.

Whatever they are made from, space graded batteries need to be able to withstand severe vibration during launch, vacuum pressure in orbit, and extreme temperatures and solar radiation. Not only should modern space graded batteries offer these properties, but they must also offer long lifetimes and high efficiency levels at a low cost.

Of course, safety is a vital factor for any space graded batteries as they need to be able to avoid short-circuiting when exposed to high or low operating temperature as well as not overcharging, which can cause overheating and potentially catastrophic explosions or fires.

Solid State Batteries

Solid state batteries have already begun to gain momentum in the automotive industry, with companies like Volkswagen achieving significant advances in the technology. Providing greater energy density, improved safety and a longer lifespan than lithium-ion batteries, solid state batteries are also drawing interest from the space sector.

Solid state batteries are different from traditional lithium-ion batteries as they use a solid electrolyte rather than a liquid one, which enables the movement of ions between the anode and cathode when charging or discharging. Solid electrolytes have a lower risk of leaks than their liquid counterparts and improved thermal stability also means less chance of fire.

In addition, the higher energy density of solid state batteries means they can store more energy in the same amount of space, providing longer lifecycles and increased range. Where lithium-ion batteries typically last for 1,500 to 2,000 charge cycles, solid-state batteries are capable of reaching 8,000 to 10,000 cycles.

Several companies are investing in solid state battery technology research to prepare for commercialisation and use in a range of potential industries, including space. Challenges around the use of solid state batteries currently include high manufacturing costs and scalability to industrial production levels.

As solid state technology emerges it will be important for engineers to understand the properties of solid electrolytes under different conditions, as well as being able to continue optimising performance and predicting potential failure modes.

Recent breakthroughs at Volkswagen, Toyota, NASA, and elsewhere have worked to improve recharge and discharge rates, storage, and safety, while also reducing weight. These breakthroughs are of interest for the space sector as they have shown battery weight reductions of 30-40% and up to triple the energy storage capacity compared to lithium-ion batteries.

What’s Next?

As battery technologies continue to develop, there will be increasing opportunities for them to spin in or out of the space sector and, as ESA Technology Broker for the UK, we can help facilitate cross-industry opportunities.

 

Sources:

https://www.esa.int/Enabling_Support/Space_Engineering_Technology/Batteries_at_the_heart_of_ESA_space_missions

https://science.nasa.gov/resource/energy-storage-technologies-for-future-planetary-science-missions/

https://www.batterytechonline.com/materials/lithium-sulfur-batteries-to-be-tested-aboard-the-iss-in-2025

https://blog.satsearch.co/2021-06-23-satellite-batteries-for-cubesats-nanosats-and-other-form-factors

https://us.mitsubishielectric.com/en/news/releases/global/2024/0509-a/index.html

https://www.spacedaily.com/reports/SpaceX_signs_battery_deal_with_South_Korea_based_LG_Energy_Solution_to_power_Starship_999.html

https://www.monolithai.com/blog/solid-state-batteries-energy-storage#:~:text=The%20automotive%20industry%20stands%20to,ranges%20and%20shorter%20charging%20times

https://www.topgear.com/car-news/future-tech/volkswagens-made-a-breakthrough-solid-state-batteries

https://www.nasa.gov/aeronautics/nasas-solid-state-battery-research-exceeds-initial-goals-draws-interest/

https://www.theguardian.com/environment/2024/feb/04/solid-state-batteries-inside-the-race-to-transform-the-science-of-electric-vehicles

https://www.volkswagen-group.com/en/press-releases/powerco-confirms-results-quantumscapes-solid-state-cell-passes-first-endurance-test-18031