Charging station availability, charging time, and range anxiety are only three of the major obstacles consumers face when operating electric vehicles (EVs), and despite the potential of battery swapping systems (BSS) to overcome these obstacles, there remain more serious issues surrounding their cost and safety. Numerous fires have resulted in casualties and injuries around the world from thermal runaway – the act of a battery overheating from overcharge, short circuits or cell related stress. As a result of these unfortunate incidents, the new area of exploration for BSS has transitioned from the initial technology needed to grasp the concept of quickly and effectively changing batteries to one of doing so safely. This has created an exciting opportunity within the battery industry as alternate rare earth metals are emerging as strong contenders for being fire-resistant battery grade materials.
At the moment, the majority of rechargeable batteries are currently made with lithium-ion (Li-ion) concentrates. The batteries have multiple grades, and while B-and-C grade batteries are cost effective, they have high internal resistance which leads to higher likelihood of fire or explosions. The popularity of Li-ion batteries stems from their high capacity, high rechargeability, low cost of production, as well as the benefit to consumers and industrial markets alike. Li-ion batteries have their fair share of drawbacks, including severely negative environmental and costly consequences from metal mining.
After three decades of popularity, the Li-ion battery’s widespread use may be coming to an end; five other battery alternatives are making large strides overcoming their respective obstacles and their benefits greatly outweigh their potential drawbacks. Globally, governments are recognizing the importance of climate change and adopting electric vehicles is a large initiative looking towards the short and long term commitment to climate change. One or more of these emerging battery substrates may be the next generation of the battery industry.
Aqueous Magnesium Batteries
Magnesium has previously been overlooked as a potential substitute for Li-ion batteries due to its affinity for moisture and passivation (coating a material to prevent it from corrosion). In this instance, magnesium forms an oxidation film that prevents redox reactions. The problem: magnesium cannot be recharged due to its tendency to passivate. To add insult to injury, the metal is also heavy and has a high ignition risk due to its high reactivity.
Despite the challenges magnesium presents, the element’s abundance, non-toxicity, and negative electrochemical potential also make it a strong contender with a fixable problem. The University of Hong Kong successfully created an aqueous chloride-based “water-in-salt” electrolyte, providing the option to regulate a magnesium-based battery system and therefore creating the possibility of rechargeability. The Chinese Academy of Science filed a patent in February of 2023 with similar outcome in mind, utilizing anion salt to prevent hydrogen evolution corrosion.
This discovery wasn’t made until early Q4 of 2022, and the lack of research grants, patents, and publications over the past five years indicate this discovery marks early success for a potential aqueous magnesium battery. That being said, the “water-in-salt” electrolyte has gained increasing popularity over the past several years, with patent numbers rising from 129 in 2019 to an additional 238 in 2022. The University of Boston has also found additional use for the new electrolyte in CO2 electrochemical reduction.
Solid State Batteries
Li-ion batteries are aqueous solutions, which present their own set of problems: overheating, leaking, and quickly losing charge. Solid state batteries are lighter because they contain solid electrolytes. The potential to reduce weight is exciting as capacity-to-weight is one of the largest considerations when implementing EV batteries – and has direct correlation to the ease of EV adoption.
Solid state batteries have been a well-investigated area of potential over the past decade, with tens of hundreds of published patents and publications in the last three years, the potential applications go much farther than just replacing Li-ion batteries. Electric vehicles are not the only mode of transportation that could benefit greatly from the emerging technology surrounding solid state batteries; the aviation industry has also made large strides in the past four years since NASA’s Solid-state Architecture Batteries for Enhanced Rechargeability and Safety (SABERS) program began researching the solid electrolyte’s possibilities, specifically considering electric aircrafts as current Li-ion batteries lack the necessary power density and design.
Toyota has taken an especially large interest in solid state batteries as they currently have over 1,0000 patents related solely to solid state batteries and have announced a 2025 roll-out of solid state batteries in hybrid vehicles. These vehicles' batteries claim to have better charge holds, drive further distances and charge faster than current EV batteries.
Seawater Batteries
Sodium is one of the most abundant alkali metals on earth as it’s found in seawater. An immediate draw to sodium-based batteries stems from their low cost, and lack of dependence on lithium metal mining.
A late 2022 publication, “Rechargeable Seawater Batteries” explains the two distinctive traits of seawater batteries that other sodium-based batteries lack: the ability to survive in an aquatic environment, as well as the ability to recharge with seawater itself. The key defining factors are the solid electrolyte, and charge-recharge functionality. The solid electrolyte acts as a natural separator between the non-aqueous cathode and aqueous anode. Sodium metal oxidizes rapidly when exposed to water or air, so the natural separation barrier creates a steadier sodium reduction at the anode, and provides an equalizing ion permeation charge.
In conjunction with the ease of extracting sodium, one of earth’s most highly abundant metals, the potential energy storage application of seawater batteries makes an even stronger case for further investigation. Similar to Li-ion batteries, seawater batteries extract sodium ions from water when the battery is charged with electric energy, storing this energy within the cathode. When the battery is discharged, the sodium is released and reacts with water and oxygen from the seawater’s cathode to form sodium hydroxide – providing an energy source that will continue to repeatedly power this process.
Graphene Batteries
Graphene batteries have proven their success, given they are as powerful as current Li-ion batteries according to a test run by the University of Queensland and Graphene Manufacturing Group. Their graphene aluminum-ion batteries are less expensive, more effective and more recyclable than current Li-ion batteries.
The patent-pending technology boasts higher power density, higher battery life, higher safety ratings and fewer environmental consequences. Unlike the traditional mining of granite, GMG takes natural gas and converts it to nanomaterial, which does not require any earth metals. The battery itself is made up of a positive and negative case, aluminum foil, separator, cathode, and spacer.
Future Applications
While many consumers weigh the pros and cons of electric vehicles, the issue of charging time and range capacity may no longer be a large consideration. As research and development continue to expand for these potential alternatives, new and exciting technologies will emerge to improve upon the cost, scalability, and environmental effects. In conjunction with these metals’ potential to be the next generation of the lithium ion battery for automobiles, their possibilities extend further into other forms of transportation, as well as home power storage systems, consumer electronics, and utility grids.
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