There are just shy of 12,000 satellites currently orbiting Earth as of June 2024, and that number is projected to rise to over 60,000 by 2030. All of them require batteries to power them when the sun is obscured from view or when they can’t harvest solar energy.
This means there is huge demand to develop high-energy batteries to power this ever-growing satellite population.
Here’s how battery technology is evolving in this field.
The growing demand for efficient energy solutions in space technology
Space is a harsh, challenging environment. High-energy-density technology is essential for mission success.
Solar energy has long been a reliable power solution in space — missions have been using solar power for decades!
Today’s technology has evolved from its 1950s-era origins, with satellite batteries reaching new levels of energy density to store excess solar energy and ensure stability during periods of darkness.
Understanding Satellite Energy Needs
Satellite power and energy requirements vary based on size, purpose and orbit. The energy requirement for a satellite is determined largely on its mission.
A CubeSat, for example, only needs a few watts, while a large, complex communication satellite could use energy in the range of tens of kilowatts.
The more work a satellite has to do, the larger the payload it has to carry. In other words, the longer its mission, the more energy it’s going to need.
Traditional energy sources used in satellites and their limitations
Solar power and batteries have been the primary energy sources traditionally used in satellites.
Fortunately, solar energy is abundant in space and reliable, providing consistent power in most orbits. However, it does have some drawbacks and limitations:
- First, solar cell energy efficiency degrades over time due to radiation damage and thermal cycling.
Solar arrays are also susceptible to damage from space debris. - The further a satellite is, the less effective solar power is, thus solar may not always be a reliable solution for missions that move deeper into space.
- During eclipse periods, solar energy is inaccessible.
- For complex satellites, large solar arrays are needed, which makes the satellite larger, heavier and more costly to launch.
That’s where batteries come in. Conventional batteries are a vital energy storage system that complements solar power. They provide power during eclipse periods and other times when solar is not optimal.
Batteries also play a pivotal role in a satellite’s initial deployment before solar panels can be activated.
However, batteries have some limitations. They:
- Add weight.
- Have a limited lifespan.
- Degrade over time.
- Pose thermal management challenges in extreme space conditions.
The Rise of High-Energy Batteries
High-energy battery technologies can offer significant advantages over traditional power sources.
Introduction to high-energy batteries and their technological advancements
Battery selection in the aerospace industry is improving with technological advancements.
Lithium-sulfur (Li-S) batteries are one example, offering a theoretical energy density of up to 500 Wh/kg, which is even higher than currently commercially available lithium-ion battery technologies. Sulfur is low-cost and abundant, offering great potential in reducing launch costs.
NASA is testing these batteries in space suits and satellites alongside the Department of Defense. They will be sent to the International Space Station in 2025, with the goal of keeping satellites like Starlink and other low-orbit equipment in orbit for longer.
While Li-S batteries are still in development, lithium-ion batteries have already demonstrated the ability to achieve high energy densities, as compared to conventional batteries. This allows for more payload capacity and reduced satellite mass.
For example, implementing Li-ion technology on the W3A telecommunication satellite saved about 200 kg of satellite mass compared to previous battery technologies.
As the above article from the European Space Agency states, lithium-ion batteries have “entirely supplanted” previous battery technology and are used in countless aerospace applications, including on the International Space Station.
Comparing efficiency and capacity
Lithium-ion batteries, especially those using silicon anode, vastly outperform conventional NiCd or NiH2 batteries.
Amprius batteries, for example, offer commercial batteries up to 450 Wh/kg with recent third-party verification of 500 Wh/kg. That contrasts sharply with NiCd at 40-60 Wh/kg and NiH2 at 45-75 Wh/kg.
The high energy density and power output of Amprius batteries make them particularly suitable for space applications where weight and volume are critical factors.
Lithium-ion battery technology has a low self-discharge rate, which means that capacity is retained. They can handle deeper discharges without significant battery loss, so capacity is used more efficiently; and they offer better performance across a wider temperature range.
Key features that make high-energy batteries ideal for space missions
High-energy battery technology, particularly lithium-ion batteries – with the exception of LFP chemistry cells – is ideal for space missions for several reasons:
- They are high in energy density, which means more energy storage in a smaller, lighter package.
- High energy density also allows for increased payload.
- With high charge and discharge efficiency, lithium-ion batteries operate in space conditions without significant capacity loss.
- They can also be charged at any point in the discharge cycle without degradation — in other words, there is no memory effect.
- With a high-radiation tolerance, wide temperature range for operation and long cycle life, these batteries get the job done, even on long, complex missions.
Applications in Satellite Operations
Communication Satellites
Communications satellites need uninterrupted data transmission for critical reasons.
Continuous service impacts essential telecommunications, broadcasting and internet connectivity. A satellite with interrupted data transmission translates to service outages that impact millions of users worldwide.
By nature, satellites of all kinds experience eclipse periods when they are not in direct sunlight, thus not receiving solar power.
Batteries are the sole power source during these times, so high-quality, energy-dense batteries are absolutely vital to transmission.
The uninterrupted power offered by batteries is also crucial to maintaining mission-critical satellite operations such as position control and data processing.
Navigation Satellites
High-energy battery technology allows for longer operational life and reduced maintenance for navigational satellites.
This is important because launching satellites is expensive.
Longer lifespans mean reduced launch costs, resulting in cost savings as multiple replacement launches become unnecessary. Fewer replacement launches also mean less space debris in the form of discarded satellites.
Longer-lasting satellites offer continuous, reliable navigation services with minimal disruptions, which is critical for everything from communication to weather forecasting.
Research Satellites
Research satellites must collect data continuously whether they are receiving solar power or not.
Batteries are critical for providing power to the satellite during eclipse periods to ensure the satellite continues to collect data. Better batteries also allow for a longer operational life allowing more time for data collection and scientific observations.
With higher energy density, lithium-ion batteries and other advanced battery technologies enable more payload, or, in other words, potentially more scientific instruments to be present onboard a research satellite.
Technological Innovations in High-Energy Batteries
Recent tech advancements in battery chemistry and design
Along with the silicon anode lithium-ion batteries and high-powered Li-S batteries mentioned above, lithium-polymer batteries are an exciting technological advancement.
These are flexible and can be shaped to fit available spaces within a satellite with energy densities that are comparable to traditional lithium-ion cells. This makes them particularly valuable for small satellites, including nanotechnology like CubeSats.
Innovations in lithium-ion batteries
Amprius has developed lithium-ion batteries with silicon anodes that achieve extremely high energy densities. Technology like the SiMaxx cells boasts reduced weight essential for aerospace applications.
Innovations in solid-state batteries
Solid-state batteries are an exciting technology that use a solid electrolyte instead of liquid or polymer like lithium-ion batteries.
These could offer energy density that is potentially double that of current lithium-ion technology, with enhanced safety as solid electrolytes are non-flammable.
While solid-state batteries are a research work in progress, Harvard researchers recently developed a postage stamp-sized solid-state battery that retained 80% of its capacity after 6,000 charging cycles and could charge in 5-10 minutes.
Future Trends in Battery Technology for Satellites
Li-ion batteries are becoming the standard for satellite applications, driven by their higher energy density, lower weight and absence of memory effect compared to older technologies like NiCd and NiH2.
We can expect the ongoing development of Li-ion batteries with improved performance for space conditions.
Lithium-sulfur batteries are an emerging technology with the potential for even higher densities. While they are not perfect and face challenges like rapid capacity fade, research continues to delve into how to best overcome these shortcomings.
Promising next-generation solid-state technology offers both higher energy density and better resistance to extreme conditions. These, along with lithium-polymer batteries, show potential for enabling new possibilities in Earth observation, communications and research.
Challenges and Considerations
Weight, durability and environmental factors in space
Reducing weight is a top priority, as launch costs are thousands of dollars per kilogram. Even in a nanosatellite, one-third of the total weight of the spacecraft is taken by the power subsystem, with the batteries weighing one-third of that subsystem.
Durability is critical in harsh space environments, with batteries required to withstand extreme temperature fluctuations, radiation, vacuum conditions and launch vibrations. This means battery technology has to go hand in hand with thermal management systems and other protective measures.
Longevity is also key, as batteries need to last the entire mission duration. Technology with improved cycle life is integral.
Safety measures/reliability in battery design and implementation
After a satellite launch, its equipment cannot be replaced or repaired. The only option is to replace the entire satellite, an expensive prospect. Because of this, any battery technology on board must be safe and reliable throughout a satellite’s mission.
Li-ion batteries need careful management to prevent overheating, overcharging or short circuits, and advanced battery management systems are needed to monitor cell voltage, temperature and charge state.
The above-mentioned environmental factors—particularly intense radiation—can degrade battery materials over time, so there is increased demand for batteries that can support longer, more complex space missions in harsh environments.
Future Potential of Batteries in Expanding Satellite Capabilities
Advances in battery technologies, including lithium-sulfur, silicon anode Li-ion and solid-state batteries, promise higher energy densities than traditional lithium-ion batteries.
This can lead to lighter satellites with more payload capacity or longer mission durations without increasing mass.
Future battery designs also strive for extended lifespans, potentially exceeding 15 years. This is critical for satellites operating for long durations without maintenance or replacement, enhancing mission reliability and reducing costs.
New battery technologies are also being developed to withstand extreme temperatures, radiation and vacuum conditions. For example, NanoTritium batteries offer a long life of 20 or more years, and durability against environmental challenges, potentially making them suitable for ongoing challenging satellite missions.
Further research/investment in energy tech for space
Space may be the final frontier, but we’ve barely scratched the surface, especially when it comes to research and investment in energy tech.
- Space-based solar power is one example. It collects sunlight continuously, which can be transmitted back to Earth as energy.
- Satellites themselves are being used to monitor greenhouse gas emissions and assess the potential for renewable energy on Earth.
- Collaborative efforts, investments in technology and a constant drive toward energy-dense, affordable, lightweight batteries will drive these innovations and others.
