Author:
Julian Skidmore, Senior Firmware Engineer, Versinetic
Date
01/01/2024
PDF
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With lithium prices at a high and abundant claims of exploitation and environmental damage from EV minerals, many people wonder if the rEVolution will stall or whether it’s even ethically and economically worth it.
That’s not true; instead, we’re entering the age of batteries: welcome to the Batterycene.
This article examines why this is the case, covering the evolution of batteries and the considerably large solution space along the way.
The first batteries were developed over 250 years ago, not coincidentally, at the beginning of the industrial revolution. All batteries today still have the same basic structure:
Battery technology progressed intermittently over the 19th century as new chemistries and processes were discovered and expanded into new applications. Some of the oldest chemistries are still in use, such as: Lead-Iron batteries for cars (and the Apple PowerBook 100 laptop from 1991); Zinc-Carbon for torch-lights and gadgets; and Nickel-Cadmium rechargeable batteries for portable phones in the 1990s.
The drive for more powerful applications resulted in Long-life Alkaline batteries for electronic gadgets from the 1980s; Lithium-button batteries for calculators, Nickel-Metal Hydride batteries in the 1990s and into the 2000s for various applications, such as smart phones, laptops, and EVs.
The term ‘battery’ is derived from Benjamin Franklin’s analogy between military units firing in unison for greater effectiveness and his experiments with multiple Leyden jars being discharged in concert in the 1700s. Similarly, Voltaire’s ‘Pile’ consisted of around 30 cells.
In other words, multiple cells in a battery are the norm. Modern EV batteries build upon this, with individual cells being assembled into parallel (for power) and series (for range) modules. These, in turn, are combined into a single battery pack.
Consequently, research is exploring every aspect of battery design, which is why EV batteries have increased their energy density from about 150Wh/kg to about 350Wh/kg over the past 10 years. The main research goals for each component can be summarised as follows:
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Figure 1: Research Goals Summary
Most changes are incremental, but even relatively small changes contribute to major improvements in battery technology. For example, the Tesla Battery Day presentation in September 2020 focused on six major objectives which would increase energy density and cost effectiveness by 56%, most of which would be achieved using straight-forward engineering solutions rather than fundamental materials research.
The improvements:
1. A new, more optimised battery cell size: 46mm x 80mm (4680), a tab-less anode which provides for shorter electron travel and high power transfer.
2. A dry electrolyte production process that is cheap and far less energy intensive and features cell testing efficiency improvements (‘formation’).
3. Silicon-based anodes (instead of graphite).
4. Pure Nickel-based cathodes (no Cobalt).
5. Simplified Cathode production.
6. Clean Lithium extraction from Nevada clay (enough lithium deposits to convert 300 million cars).
Yet, battery research funding is rapidly increasing across the globe.
The EU is catalysing €8.2bn of research; the US $3bn in its EV development programme which includes at least $1bn of battery research. Chinese research made LFP batteries a realistic proposition for EVs.
What this means is that we can expect similar improvements in battery capabilities in the next decade or two.
Materials
Although we think of EVs as having Lithium-Ion batteries, in fact their chemistries are different from those in most portable applications (EVs, remember, are also portable applications), primarily because they need to trade-off a slightly lower energy density for far more recharge cycles.
A summary of the main areas of battery research, against the primary battery components:
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Figure 2: Summary of main research areas by component type
Primary battery components
Solid-State electrolytes replace flammable liquid-gel electrolytes in current batteries, which improves reliability, but also increases potential energy densities and charging rates.
Interphase research aims to reduce battery inefficiencies and damage due to the buildup of a chemical layer between the anode and electrolyte over charging cycles.
Salt-composition has an effect on the cost and performance of batteries, such as their thermal range.
Polymer Gelelectrolytes could triple the lifespan of a battery.
Dendrite Elimination is critical for eliminating potential short-circuits due to the growth of cathode filaments across the electrolyte during charging cycles.
Graphite permits rapid energy transfer from a lithium-ion electrolyte, but the process is expensive, energy intensive and generates particulates, which synthetic substitutes aim to address.
Silicon-Carbon anodes aim to improve EV battery range and charging speeds.
Lithium-Titanate anodes should help to increase the number of charging cycles.
Tin/Cobalt Alloy may help reduce lithium deposition on anodes.
Surface Area improvements to anodes increase energy delivery and charging rates.
Cobalt Reduction is important because of the use of child and forced labour in manufacturing conventional NMC (Nickel Manganese Cobalt) Lithium ion batteries (as well as the refinement of fossil fuels). The difficulty in tracing the origins of cobalt, despite international efforts to regulate other conflict minerals, means there are major efforts to reduce Cobalt use.
Aluminium Usage could help reduce the cost of backup batteries and improve charging rates.
Iron Phosphate cathodes are already being used in a number of Chinese EVs as well as Tesla Model 3 cars. They have lower energy densities, but reduce the cost of batteries and the amount of nickel and cobalt.
Lithium Air cathodes have the potential for the highest energy density of any kind of lithium battery.
Sodium Ion batteries replace lithium to provide much cheaper EV batteries with energy densities comparable to Lithium ion batteries about 8 years earlier.
Spinels offer the potential for low cost, environmentally-friendly and thermally stable cathode materials.
Porosity improvements are critical for the rate of electron discharge and battery safety.
Tension unevenness across the separator affects the performance of an EV battery.
Silica Membranes offer the potential for greater electron discharge and higher levels of safety, among other benefits.
Cylindrical cells in EV batteries can help provide structural strength, ventilation, and a high energy density per weight.
Flat Pouch battery containers provide flexibility and high energy density per volume.
Cell Size improvements help to increase energy density, reduce cost, and reduce the amount of resources in production.
Thermal Management is dominated by the container design at the cell, module, and pack level, affecting charging rates, longevity, and safety.
Several areas of ongoing research reveal both the potential for a huge amount of improvement over current EV battery technology, and for multiple solutions across the range of EV battery (and battery storage) applications.
Although a lack of basic minerals is frequently cited in the press as a limit on our ability to transition to clean technology, many of the chemistries being explored for current and future batteries are actually derived from elements that are abundant on Earth relative to our battery needs:
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Figure 3: Availability of materials for current production
These values are in metric tonnes per person. Overall values appear very large; however, just a meagre fraction of these resources can be sensibly extracted, and only a small fraction of those are really needed for society as a whole.
For example, a 2016 Tesla Model S with a 73kWh, 453kg battery contains about 63kg of lithium carbonate equivalent (Li2CO3), which amounts to 12 kg of lithium. In reality, we only need about 5kWh of transport per day (about 20 miles) on average, which is less than 1kg of lithium per person, or approximately 0.8 millionth of a percent of the possible global lithium.
Given the relative abundance of lithium, we ought to be surprised at the current high cost; however, this is more a function of current lithium reserves and exponential demand rather than global content. Aside from demand, the extraction of lithium is the next bottleneck in that it is evenly distributed at very low concentrations globally, and only a few locations contain relatively high concentrations. In addition, high concentration locations may constrain other resources (such as water), be located in unstable regions (such as Iran), or be in protected areas for indigenous populations (for example, North American First Nations sacred land).
The fixation on lithium is also a distraction from the abundance of other materials that can be used for practical battery chemistry. The use of Lithium Iron Phosphate (LFP) batteries in European and Chinese Tesla Model 3 cars, for example, means that Cobalt and Nickel can be avoided (the lithium content is still roughly the same, about 160g/kWh).
Or, take the prospective introduction of the Sodium-Ion based BYD Seagull; this could open up a large market for shorter range, but much lower cost EVs (the Seagull has an energy density of about 120 Wh/kg, similar to early EVs) and is projected to cost around $12K for 305 km of range [30 kWh]).
Ultimately, multiple, abundant materials are usable for batteries because the key insight is the re-usable storage of energy in electrons, and all elements contain electrons (though not all can easily form the ions needed for energy transfer).
This makes it fundamentally different from historical energy generation, which is about burning a material to release thermal energy, which can be converted to other forms such as, fossil fuels or hydrogen.
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Sufficiency
As the global economy gears up for a net-zero future, treating rechargeable battery production and use as just more consumerism is misplaced, not least because rechargeable batteries are designed to be recharged rather than being single-use.
EV batteries and emerging battery technology are all new enough for their engineers and designers to have been well aware of the need for recycling before the start of their battery life cycles way back in the late 1990s and early 2000s.
In addition, it is more sensible - and cheaper - to recycle batteries than extract more raw materials. In the medium term, we can expect the costs of new battery materials to decrease as efforts to find new reserves increase and to get higher once again as this process becomes more challenging compared with the cost of reuse and recycling.
There is little in the way of EV battery cycling currently, but this is because EV batteries have lasted much longer than most people expected; therefore, very few EV batteries have reached end-of-life.
Also, it is expected that EV batteries can then perform many more recharge cycles as powerwalls, substations, or substation / renewable energy base loads, before they become impractical for commercial usage.
Nevertheless, battery recycling has already been started by Volkswagen, Renault (/Nissan) and Tesla as well as independent recycling facilities.
Unlike fossil fuel extraction, which currently runs at 15 billion tonnes per year, at basically the same rate it is consumed, mineral extraction for clean technology would require less than 1/500th of the mining, by 2040. This is partly due to efficiency gains (⅔of fossil fuel energy is wasted as heat, and about 40% of cargo shipped is fossil fuels themselves).
At the same time, electronic devices are steadily becoming more efficient. Together, these factors mean that over the next few decades, clean technology resources will become highly (if imperfectly) reusable and thus sufficient for our needs.
Diversity
It’s certain that battery usage will grow phenomenally over the next several decades as we shift towards full decarbonisation in energy production, transport, and manufacturing.
This means there will be many applications for batteries, but it doesn’t mean all those applications have the same battery requirements.
Consider large-scale gigafactories. They don’t need to be mobile, or compact, so they don’t need to have the same energy density. As a result, chemistries such as Zinc-Bromide flow batteries may become the norm, and other renewable energy storage solutions will play important supporting roles, offloading the resource constraints on lithium batteries to true high energy density applications, such as short-haul aircraft.
In addition, just because so much attention is given to new battery developments doesn’t mean that established rechargeable battery technology, such as Nickel Metal Hydride (NiMH) batteries, is obsolete. They too will continue to play a role in existing applications (e.g., rechargeable AA batteries), or novel transport applications now that the patents have expired.
As charger infrastructure matures, EV batteries might not need to be as large as they are today for most EVs, while the shift towards transport as a service (or TAPS, Transport as a Public Service) would increase the diversity of modes of transport. Thus allowing the majority of vehicles to be much smaller (because they’d only need to carry one or two people) alongside a minority of vehicles for more demanding needs (pickups, vans, and HGVs).
Furthermore, load balancing and the smart grid are natural fits for battery applications, allowing us to make better use of renewable energy and reduce energy costs without compromising our energy needs.
Conclusion
While Lithium-Ion batteries seem omnipresent in today’s technology, it is timely to remember that a large variety of battery designs have been developed over the course of the past two centuries. With the feverish pace of current battery research, we have seen at least a 3-fold improvement over the past 10 years, and all the indications are that this will continue into the next few decades.
Fossil fuels provide many sources as well as many means of refinement to suit multiple applications with different needs, but the much greater flexibility of battery technologies makes them eminently equipped to meet the multiple needs of our zero-carbon future.
This does not mean, though, that the transition will be easy: a significant proportion of global GDP will be required to unlock the potential of battery storage, both for research and deployment. The primary issue we face - limitations in scaling up battery resourcing to meet current and future demand, as opposed to any material limitations themselves.
In the end, this means batteries look set to be the defining factor holding our clean technology future together.
