In an earlier blog Sam Bailey discussed the growing demands for high performance battery technologies to meet current and future energy storage needs. The increasing commercial and environmental importance of meeting these needs is leading to increased investment in this sector and acceleration in the rate of innovation. The investment in battery technology comes from a wide range of industries and is of sufficient importance that many governments, including the US and UK, are also investing heavily.
In renewable energy, innovations in the battery sector will be vital to the development of appropriate local power storage which in turn should enable a higher proportion of worldwide electricity production to rely on periodic renewable generation systems.
In the world of electric vehicles, cheaper, lighter more environmentally friendly battery technologies will be necessary for this type of vehicle to be widely adopted and to meet the goal of providing truly sustainable personal vehicles.
There is even a growing body of research into electric or hybrid powered airplanes. The reduction in traditional fuels for airplanes would go some way to reducing the environmental impact of our increasing international flight habit. Although it is thought that large scale role out of electric airplanes is still many years away, Zunum Aero collaborating with 24M ambitiously hope to introduce a 12 seater short distance hybrid airplane in 2022.
The need for new battery technologies to satisfy these industries and many others is clear. Additionally, there is ever increasing public interest in our use and production of energy linked with issues climate change and growing concerns about damage to the environment. As such, innovations that provide more sustainable products are highly sought after to match consumer demands.
In this blog we look at a few of the new types of battery technology that might provide the batteries of the future.
Development of these traditional battery types comes in many forms from new materials to complete redesign of the battery structure.
Researchers at Lawrence Berkeley have been using computational methods to rationally design disordered lithium cathode materials with high energy densities amongst other improved cathode materials.
24M have developed a semi‑solid lithium ion battery which it hopes to deliver to market in 2020. Increased energy density comes as a result of the removal of 80 % of the inactive material typically needed in a lithium ion battery by developing semi‑solid cathode and anode materials separated by a non‑porous conductive membrane.
Lithium metal type batteries have been known for many years in a research setting but problems of short circuiting lithium due to dendrite formation during charging and high reactivity of lithium metal have largely held this technology back. Despite this obvious drawback, there is keen interest lithium metal batteries still due to the promise of energy density up to twice that of a lithium ion battery.
Solid Energy Systems have developed lithium metal batteries made using lithium foil and a proprietary non-aqueous electrolyte made up of a fluorosulfonyl imide salt and a perchlorate salt (EP3262706). A first product line is already available particularly for use in drones with a second product expected to hit the market in 2020 for electric vehicles.
Researchers at Stanford University have also recently developed a coating which prevents dendrite formation in lithium metal batteries potentially providing a solution to one of the main problems with these type of batteries.
These advances make lithium metal batteries a viable option to replace or co-exist with lithium ion battery technologies in future.
Solid State Lithium Metal
Solid state lithium metal batteries are widely considered to be a significant development in battery technology. Solid state refers to the solid nature of the electrolyte in these batteries. The obvious advantages that come with the replacement of a liquid electrolyte with a solid are improved safety but also include more energy dense and lighter batteries (Nature Energy, 2016, 16030).
Solid Power announced recently that it had begun production of lithium metal solid state batteries which use an inorganic solid electrolyte. Solid Power have been partnering with car manufacturers so it seems likely that this technology will be seen in cars first.
Researchers at Tohoku University have developed a complex lithium hydride superionic conductor that showed high stability against a lithium metal anode and a high conductivity of 6.7 mS/cm (comparable to current liquid electrolytes which are around 10 mS/cm). The material enables all-solid-state lithium-metal batteries to be produced with an energy density in excess of 2500 Wh/kg. This compares very favourably to lithium ion batteries which typically have energy density of from 100 to 300 Wh/kg.
At varying stages of development, these solid state batteries show clear promise.
Metal–air batteries, such as zinc-air, aluminium‑air and lithium‑air, are of interest due to their potentially high energy densities. The theoretical specific energy densities for metal–air batteries are higher than for ion-based methods which make them attractive commercially for providing lower weight energy dense batteries.
Phinergy have demonstrated that an aluminium‑air primary battery can provide an electric vehicle with a driving range of over 1000 km. In comparison, electric vehicles on the market today reportedly provide from 380 to 500 km of driving per charge. These batteries are not rechargeable and so commercialization would also rely on other infrastructure (e.g. to replace the batteries and recycle the aluminium oxide) before widespread adoption is viable.
These are just a hand full of the many battery technologies at various stages of development today. Whilst it is generally considered that, at least in the short term, battery advances will come from incremental development of traditional lithium ion type batteries it is clear that we are ever closer to commercial realization of different forms of battery so in the longer term, even the sky may not be the limit for battery powered technologies!