Batteries are critical for military missions since mission success and soldiers’ lives often depend directly on a military battery’s performance. “Batteries enable radio communication among combat squad members and field headquarters. They provide the power to obtain accurate location data essential for maneuver and combat air support. Laser range finders and night-vision goggles are two more examples of battery-powered capabilities that give U.S. troops battlefield superiority,” says RAND.
Batteries represent the major limitation on the expanded implementation of wearable computing devices — from communications to health monitoring to chemical/biological/radiological (CBR) sensors to helmet-mounted displays of real-time maps and data from other warfighters, other units, field headquarters, UAVs, satellites, and manned airborne platforms.
As military platforms and systems such as land vehicles are fitted with more electronic equipment, their electrical energy demands will continue to increase and it is anticipated that their limited electrical energy storage capabilities (i.e. their batteries) will present issues during the vehicles’ life of type. Furthermore, the development of hybrid electric vehicles (HEV) and electric vehicles (EV) has introduced new performance requirements on the batteries used in land vehicles.
Military operations present unique requirements, which differ from those of most cars and commercial vehicles. Batteries on military land vehicles require high energy (for silent watch) and must also be capable of delivering high power (for engine starting and load leveling). Furthermore, they must withstand harsh military environmental conditions and should provide sufficient overhead to accommodate future growth in vehicle electrical power requirements.
Battlefield deployments away from supply depots typically last for 72 hours or longer. Under these circumstances, short-lived batteries could prove fatal to warfighters relying on in-uniform communications and other devices. The expected improvements in energy density may enable advances in directed energy weapons, increase the loiter time of unmanned vehicles, lead to more effective sensors, and reduce the size and weight of man-portable systems. In addition to requirements for characteristics of battery performance, requirements are established for battery survivability in harsh conditions.
A typical current 72-hour mission requires each Soldier to carry more than 20 pounds of batteries on top of their already-heavy combat gear and the future advanced equipment will require significantly more energy and power. In order to advance beyond the current limitations of modern battery technologies, the U.S. Army’s agreement will pursue several research themes that explore the full extent of a battery’s capabilities, including:
· Extreme Charging – to facilitate the rapid return of critical Army systems to battlefield readiness
· Extreme Safety – to reduce or eliminate the flammability/explosive risk of batteries to the warfighter
· Extreme Voltages – to enable batteries which can be charged to higher voltages to achieve a higher energy density and thus reduce the battery mass burden for the warfighter
· Extreme Evaluations – to better understand the inner workings of batteries and their degradation mechanisms, thus facilitate the transitioning of advanced battery materials from basic research into the commercial cells used for Army batteries
· Extreme Transformational Innovations – to further enable these Extreme capabilities and promote the development of new materials and novel battery designs such as solid-state lithium batteries
Lightweight, long-lasting, fast, and field-rechargeable batteries are in heavy demand. Because the rate at which chemicals within a battery react is dependent on temperature, reactions proceed more quickly as temperature increases. This means that, for military batteries, great care has to be taken to ensure that the power generated in a cold-weather environment is sufficient to meet a soldier’s needs.
On the other hand missions in high-temperature regions face overheating challenges. It is well known that certain battery cell chemistries, lithium-ion for example, are susceptible to overcharging and to over-discharging operational problems. Occurrences of these conditions and other events can cause a reduced useful battery life. In the extreme, destructive mishaps involving intense heat, fire, and even explosion can occur. Because a battery is an energy storage device, by definition a good battery contains large amounts of energy in a confined space. Relying on flammable and combustible materials, current Li-ion batteries (LIBs) are susceptible to catastrophic fire and explosion incidents — most of which arrive without any discernable warning. Notably, Samsung Galaxy7 phones were banned from airlines because of this danger, and the Navy’s prohibition of e-cigarettes on ships and submarines is a direct response to the obvious need to reduce the flammability of the power source of choice for portable electronics, electric vehicles, and more.
Safety, therefore, is a paramount concern, and it must be established that Soldier Portable batteries (SPBs) will fail gracefully, i.e., without damaging other components of an electrical system or posing a danger to operators. Graceful failure must hold in the face of many different types of possible abuse. Requirements cover the testing necessary to establish the battery’s response to explosive decompression, submersion, thermal and mechanical shock, sand and dust storms, and numerous other environmental hazards that a military battery might encounter during its service life.
For military purposes, battery cost is secondary to dependability. Therefore military is willing to pay somewhat higher prices to ensure that its batteries will be effective in combat situations and rugged environments.
The U.S. Army awarded $7.2 million to the University of Maryland to lead an alliance of the nation’s top battery researchers, further propelling battery advancements. The cooperative agreement is the latest Army research campaign on extreme battery technology. In addition to these target goals, researchers will also examine existing battery systems and modify them to better suit the Army’s needs.
“This variety in battery applications leads to variety in the types of batteries that the military acquires; a battery cell designed to periodically provide small amounts of power to a flashlight is built differently than a large, one-shot cell inside a missile, which may lie dormant for many years and then be expected to provide a large amount of power at a moment’s notice.”
The advantages of Li-ion battery are reduced when used in high-temperature environments or is forced to generate large currents for extended periods of time. Two nickel-based chemistries are also used in rechargeable batteries: nickel-metal-hydride (NiMH) and nickel-cadmium (NiCd). Both chemistries involve positive electrodes made of NiOOH (nickel oxyhydroxide) but differ in the materials used in their negative electrodes. NiMH has largely replaced NiCd because of its much greater specific energy and lower toxicity. NiMH batteries are competitive with Li-ion technology in some applications, and can match the lower end of the Li-ion battery spectrum in specific energy.
When compared to Li-ion technology in other respects, though, NiMH batteries have several disadvantages. For example, their high self-discharge rate keeps them from being stored for any length of time without needing to be recharged. Battery structures with lower self-discharge have been introduced, but generally have lower capacity than standard varieties.
For years, scientists and researchers are looking to improve lithium-ion battery technology or develop new battery chemistry or materials that would enhance battery performance and contribute to the wider adoption of renewable energy, energy storage, and electric vehicles. For example, earlier this year, researchers from the Samsung Advanced Institute of Technology (SAIT) and the Samsung R&D Institute Japan (SRJ) created a prototype of a new type of solid-state battery with high energy density, half the size of a typical lithium-ion battery, that could enable an electric vehicle (EV) to travel up to 500 miles (800 kilometers) on a single charge.
Others have been trying to make lithium-oxygen batteries a viable energy storage solution by overcoming some of the challenges to the commercial use of this type of batteries. Oak Ridge National Laboratory researchers said in May 2020 they had developed a thin-film, highly conductive solid-state electrolyte made of a polymer and ceramic-based composite for lithium metal batteries.
New battery could provide substantial power to Soldiers without risk of fire
Army scientists and their partners at the University of Maryland and Johns Hopkins Applied Physics Laboratory have developed a high-energy aqueous lithium-ion battery that won’t catch fire no matter how damaged it becomes. These new batteries continue to operate in conditions where traditional batteries fail.
Lithium-ion batteries have the potential to deliver enormous amounts of energy, but that power often comes at the cost of safety. When lithium-ion batteries get punctured or become overheated, they can cause deadly fires that even water can’t extinguish. For the Army, a battery that can power high-energy electronic devices while withstanding extreme abuse would be vital for enhancing Soldier capability and survivability in the modern battlefield.
“Our project addresses the risk by allowing high-energy or high-power batteries to be put on the soldier with no risk of the batteries catching on fire,” said Dr. Arthur von Wald Cresce, a materials engineer at the U.S. Army Combat Capabilities Development Command’s Army Research Laboratory. “We’re hoping that by designing safety into the battery, this concern goes away and Soldiers can use their batteries as they please.”
Traditional lithium-ion batteries catch fire because the electrolyte in the battery is oftentimes a flammable organic compound that is sensitive to temperature, he said. When these batteries become damaged, they can generate significant amounts of heat and ignite a fire with the electrolyte as the fuel. Aqueous lithium-ion batteries navigate around this problem by using a nonflammable, water-based solvent as the electrolyte for the battery. In addition, this new technology uses a lithium salt that is not heat-sensitive, allowing for the battery to be stored at a much wider range of temperatures.
“If the battery’s temperature in storage happens to spike to 150 degrees Fahrenheit, the battery won’t cease to operate,” Cresce said. “In fact, it’ll probably still operate the same. Most importantly, it will not sustain a flame, so any damage to the battery will result in, at worst, a battery that doesn’t deliver anymore voltage.” This research, part of the laboratory’s Center for Research in Extreme Batteries, began in late 2014 with the goal to promote research collaboration the lab and partners in industry and academia.
Cresce and the team first collaborated with scientists at the University of Maryland to study the properties of a new class of aqueous electrolytes known as water-in-salt electrolytes. In November 2015, they published their findings in the journal Science. Recently, Cresce and the team made a major breakthrough in their research when they created an aqueous lithium-ion battery prototype with a maximum potential of 4 volts, which is around the same amount of energy found in typical lithium-ion batteries.
Army scientists significantly improved the design of the battery to make it even easier to produce. With the latest version of the aqueous lithium-ion battery, Cresce and the team created a special polymer gel to encase the anode instead. This gel layer not only does a very good job of repelling water, but it is also much less volatile than the ether solvent, he said. “We are now able to construct batteries without worrying if the protective layer has evaporated or not,” Cresce said. “Additionally, the gel is very easy to make. We have been using short doses of ultraviolet light to cure the gels just like any plastics manufacturer or label and packaging printer.”
Cresce envisions that when safe 4-volt lithium batteries are available for the Soldier, energy supplies would come equipped with less bulky, protective packaging, which would reduce the weight of the gear that Soldiers would have to carry. “Every Soldier we talked to would like to carry less batteries and would like to be able to use their equipment without having to really think about how it’s powered, and the aqueous lithium-ion batteries allow them to do these things,” Cresce said. “The batteries can be packaged less heavily so they can carry more energy effectively, which means less battery changes and less batteries carried.”
Not only that, aqueous lithium-ion batteries may influence the development of future electronic devices because the batteries can be made in different shapes and sizes, allowing for a more flexible and efficient design. Cresce said the Army hopes to integrate the aqueous lithium-ion batteries into hybrid and electric military vehicles with the added possibility of expanding the technology into the commercial vehicle industry. He largely credits the growth of the aqueous lithium-ion battery research at the laboratory to the efforts of his fellow team members and the support of Army leadership.
“With just one year accelerated funding, we were able to take our bench technology and turn it into a prototype,” Cresce said. “We’re going to manufacture prototypes with the hopes that we can get this into the field between 2026 and 2028 on a device that the soldier can wear and use in the field. I really hope we can stick that timeline, because it would fit in very much with the modernization of the U.S. Army as we move forward.”
A team of researchers from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, has realized another landmark achievement with their breakthrough lithium-ion battery technology. The flexible Li-ion battery that can operate under extreme conditions — including cutting, submersion and simulated ballistic impact — can now also add incombustible to its resume. In research published recently in the journal Chemical Communications, of the Royal Society of Chemistry, the team updates its latest discovery: a new class of “water-in-salt” (WiS) and “water-in-bisalt” (WiBS) electrolytes incorporated in a polymer matrix that reduces water activity and elevates the battery’s energy capabilities and life cycle — while ridding it of the flammable, toxic and highly reactive solvents present in current Li-ion batteries. It’s a safe, powerful alternative.
Lithium-thionyl chloride battery pack
Lithium-thionyl chloride cells (Li-SoCl2) have a metallic lithium anode (acknowledged to be the lightest of all the metals) and a liquid cathode, comprising a porous carbon current collector filled with thionyl chloride (SOCl2).
Lithium thiol chloride batteries, while not rechargeable, meet many of military requirements. They are compact and lightweight, have extended runtime, and are able to operate in temperatures from -30 to 140 degrees Fahrenheit. Nevertheless, greater advances are required for in- or on-uniform power to handle everything currently in development for wearable computing.
The batteries are defined by high voltage and energy, long storage, and the lowest self-discharge rate. The self-discharge of Li/SOCl2 battery is less than 1% per year at 20℃, which can support long storage periods and achieve a service life of 10 to 20 years. The batteries are suitable for long-term applications, such as automated meter reading, alarms and security wireless devices, mobile asset tracking, medical equipment, GPS, military radio communication, oil exploration and automotive telemetry, and especially as a backup power source for memory ICs.
Lithium-sulphur is a closely watched technology that can also be used for military and aerospace applications. The batteries’ energy density is at least twice that of current lithium-ion batteries. Oxis Energy, an Oxfordshire-based company that has a patent for lithium-sulphur batteries, says it has achieved a theoretical energy density five times greater than lithium-ion. It is working with Seat, the Spanish car brand owned by Volkswagen. Nasa, the US space agency, has invested in lithium-sulphur batteries for exploration missions.
For the technology to move from experiment to commercial product it will need to achieve longer life cycles. Mr Gonzalez at IDTechEx adds that start-ups must be able to produce the same-quality batteries in large volumes.
The Army battery you can cut in half and still use
Researchers at the Johns Hopkins University Applied Physics Lab have designed, along with scientists from the University of Maryland and the Army Research Lab have developed a cuttable, foldable, submersible battery. “We can make a battery in the form of a sheet, and then you can literally cut it with scissors, apply an electrical contact and you’re done,” said Jeffrey P. Maranchi, program manager for signature, energy and materials science at APL. “It’s profoundly important for the DoD to have mission flexibility, and this significantly increases your operational agility.”
In the paper “Flexible Aqueous Li-ion Battery with High Energy and Power Densities” in the journal Advanced Materials, researchers describe a method for replacing the battery’s usual electrolyte medium with something more simple and stable: Water. Lithium-ion batteries offer high energy density – that’s the amount of energy you can pack into a small container. “But what makes them achieve great performance is also what makes them dangerous,” said Kostas Gerasopoulos, senior research scientist and principal investigator at APL. These batteries typically are volatile: They can explode or catch fire, making them hazardous to transfer or store.
Researchers, in their quest to find a cuttable, flexible, waterproof battery, also wanted to develop a more stable energy source. They say water is the ideal medium. To thicken their mix, the APL added salt. “You’d think that having a lot of salt in water, it would never dissolve. But this salt can be dissolved in very high concentrations, and it suppresses the electrochemical activity of water,” Gerasopoulos said. The salt allows the water to build up the kind of energy density found in conventional lithium-ion batteries. That gave the team the kind of safe, stable, high-density energy source they felt would function well in a military setting.
The Army awards the University of Maryland $7.2 million to solve battery technologies limitations
The U.S. Army Combat Capabilities Development Command’s Army Research Laboratory will work on the UMD-led effort, in partnership with Montana State University, and other universities, national laboratories and companies, which are part of the Center for Research in Extreme Batteries.
Prof. Eric Wachsman, director of the Maryland Energy Innovation Institute and the William L. Crentz Centennial Chair in Energy Research, and Prof. Chunsheng Wang, director of CREB and the Wright Distinguished Chair of Chemical & Biomolecular Engineering, will lead the effort for UMD. Prof. Lee Spangler, director of the MSU Energy Research Institute, will lead the effort for MSU.
“The Army is looking to add a wide range of diverse new capabilities in the next five to 10 years,” said Dr. Jeffrey Read, an Army chemist and one of the team leaders for the laboratory’s Battery Science Branch. “The amount of power and energy required for the average Soldier is going to increase dramatically when these systems are fielded, so batteries become critical.” This effort also includes Argonne National Laboratory, Brookhaven National Laboratory, the National Institute of Standards & Technology, Graphenix Development Inc., Ion Storage Systems, the New York Battery & Energy Storage Consortium, Saft America, Stony Brook University and the University of Texas-Austin.
According to Read, future Soldiers will depend on numerous electronic devices to complete their mission. These technologies, which will include secure tactical radios; goggles with thermal and low-light sensors, rapid target acquisition and aided target identification, augmented reality and artificial intelligence; the next-generation combat rifle; unmanned aircraft systems; counter-IED equipment and more, rely on large amounts of battery power that Soldiers have to carry with them to the battlefield.
“Soldiers use batteries differently from the standard practices of everyday users,” Read said. “Army batteries are stored fully-charged for long periods of time. When used, they are often fully depleted (fully-discharged). The environments in which they are stored and used are often much hotter or colder. All of this is extremely hard on the inner chemistry making the batteries function. Part of the work is to try to evaluate commercial batteries or new battery systems in a way that is more reflective of how the Army uses batteries.” By assembling together in this consortium effort many of the top battery researchers in academia, industry and government laboratories within the U.S., this agreement aims to rapidly accelerate the progress of battery research to better enable Soldiers to retain transformational overmatch capabilities over their future near-peer adversaries.
“The Army is rapidly increasing its usage of batteries for diverse applications, including portable soldiers systems, unmanned vehicles, hybridized next-generation combat vehicles, directed energy systems and more,” said Dr. Wesley Henderson, the laboratory’s lead for CREB. “The focal themes for this collaborative effort bring together many of the top battery researchers throughout the U.S. to directly address the most challenging barriers to implementing the transformation of the present Army into the future Army needed for longer duration missions with more electrified devices, a limited resupply of batteries due to restricted logistics and the larger battery systems essential for enabling new capabilities.”
The U.S. Army Combat Capabilities Development Command’s Army Research Laboratory will work on the University of Maryland-led effort in partnership with Montana State University and other universities, national laboratories, and companies that are part of the Center for Research in Extreme Batteries. The cooperative agreement also includes research entities and companies in the battery and energy storage sector, such as Argonne National Laboratory, Brookhaven National Laboratory, the National Institute of Standards & Technology, Graphenix Development Inc, Ion Storage Systems, the New York Battery & Energy Storage Consortium, Saft America, Stony Brook University and the University of Texas-Austin.
This agreement represents only one of many collaborative efforts that the laboratory oversees as part of its Open Campus Initiative. Throughout the duration of this program, the lab will directly assist with the research, as well as facilitating the interactions between the collaborators. “ARL battery scientists will be working closely with many of the projects through direct research interactions and, in some cases, supervision and mentoring of student and postdoctoral fellow researchers,” Henderson said. “As the CA manager, I will also be closely supervising the work conducted and aiding the researchers in interfacing with the Army scientists and engineers, as well as with each other.”