The Actual Future of Energy
Preface
As the climate continues to deteriorate, the need for innovative, electric solutions is rising. And not just any old tool, we need electric solutions that are more viable than carbon-emitting ones.
However, there’s still one hurdle that we need to overcome in order to achieve this ambitious goal: impotent lithium-ion batteries.
Lithium-ion batteries have become the key limiting factor in several innovative technologies today — the main problem preventing mass entry of potentially world-changing technologies.
Disrupting lithium-ion batteries would not only significantly improve our global ecological footprint, it would also genuinely improve our innovation output.
The Future of Transport
This is probably the most applicable in the transportation industry, where our inefficient solutions are emitting unsustainable amounts of greenhouse gasses, and seriously lacking in performance.
The wide-scale adoption of electric vehicles would not only allow for more sustainable automobiles, it would actually tremendously improve vehicle standards as well.
The majority of parts in cars and especially planes are directly linked to assisting the gasoline engines run. Since batteries are automatic electrochemical engines, this entire process is run, managed and maintained by the battery itself — no need for additional parts. This allows cars and planes to be cheaper, and significantly more aerodynamic in contrast to their gasoline counterparts — almost.
The Problem
The biggest technical gap preventing this breakthrough is cost. More specifically, material cost. The cost of energy for charging your electric vehicle isn’t as big of an issue as the actual upfront cost of purchasing the battery.
In addition, energy density — the energy capacity of batteries per kilogram — needs to be improved in order for cars to go longer distances without recharging.
If we can solve these two challenges, however, electrical vehicles could become more viable than gasoline cars — an outcome which would greatly benefit society. With that being said, let’s figure out how we can achieve this ambition.
Batteries 101
In order to understand how we can radically improve lithium-ion batteries, we first need to understand how they work. Conventional lithium-ion batteries contain 4 key parts:
- Anode — a negative electrode that releases electrons to the external circuit and oxidizes during an electrochemical reaction
- Cathode — a positive electrode that acquires electrons from the external circuit and is reduced during the electrochemical reaction.
- Separator — a semipermeable barrier that allows the lithium-ions to pass between the electrodes, but prevents the free electrons generated in the anode from moving through the barrier.
- Electrolyte — a liquid spread throughout the entire battery serving as a conductor to allow the lithium-ions to traverse between the electrodes and barrier.
The Cycle
When the lithium-ion battery is charging, two things happen. Firstly, the reduced lithium-ions in the cathode traverse the separator to the anode for oxidation. Secondly, the current flow is reversed, conducting the electrons currently in the cathode to the anode.
The lithium ions are then oxidized in the anode in order for them to “insert themselves” — intercalate — into the graphite molecule (C₆).
When the lithium-ion battery is discharging, a couple of things happen. Firstly, the lithium ions are passed through the separator via the electrolyte to the cathode. This movement converts the chemical energy from the lithium ions into electrical energy — creating free electrons in the anode.
Due to the fact that the barrier prevents the electrons from flowing to the cathode within the battery itself, the electrons must then travel through the conducting wire of the connected external circuit all the way to the cathode. This is how the current — the flow of electrons — is created in circuits.
The lithium-ions are then reduced in the cathode, allowing them to once more intercalate — just this time in the opposite electrode. This redox cycle is essential because it allows a traditionally unstable element (lithium ions) to mix with other molecules without changing the chemical makeup of the ions too much.
Challenges
Alright, hopefully that made sense. Now that we’re clear about how batteries work, let’s explore the design flaws with lithium-ion batteries that drive the high costs and inadequate energy densities.
Cost
In order to store lithium after reduction, cathodes are made out of lithium containing metal oxides. This facilitates the entire intercalation process discussed earlier.
The most commonly used cathode material is cobalt due its relatively strong energy density. Unfortunately, that comes with a pretty high cost — literally.
More than 50% of the world’s cobalt supply is sourced from the Democratic Republic of Congo, a region afflicted by corruption, unethical practice and especially violence.
This over the past decade has resulted in rapidly less mining operations and cash investment from mining companies. What’s worse is that cobalt is usually mined as a byproduct of other mining operations, further decreasing the supply.
Due to this vast divergence between the supply and demand, cobalt prices are skyrocketing out of the roof — the main driver for expensive costs in lithium-ion batteries today.
Energy Density
Energy density is defined as the total capacity of the battery in relation to its size. In order to increase the energy density — resulting in more energy released per charge-discharge cycle — we need to use a smaller anode material. This is due to the fact that any anode molecule takes up space in the anode section of the battery, preventing more lithium ions from being passed in.
That’s the rational behind the graphite (C₆) anode molecule. It’s a super tiny element, allowing the allocation of more space for lithium ions.
Seeing as graphite is one of the smallest possible solutions, it’s unreasonable to assume that any other anode material would catalyze a significant improvement. However, as you’ll soon see, we can still innovate in this space by going in a new direction entirely.
Lifespan
The root cause of short lifespans in solid-state batteries are dendrites. Dendrites are branching networks of lithium which grow through the liquid electrolyte during charging of a battery, causing short circuits and piercing the separator.
Dendrites originate in a structure called the solid-electrolyte interphase, in which the solid lithium surface of the anode meets the electrolyte. The catalyst of the dendrite growth process is known as ethylene carbonate, an indispensable solvent added to the electrolyte to enhance battery performance.
In addition to significantly reducing battery lifespan, if a dendrite manages to poke a hole right through the separator, anode and cathode materials might touch. This would result in extreme overheating that would combust the already flammable electrolyte — resulting in lithium-ion’s infamous explosions.
Charging Speed
The root cause of slow charging speed is temperature resistance limitations. You could very easily just dial up the voltage while charging (releasing more lithium ions from the cathode + sending them to the anode), however due to ohm’s law, this would increase the heat produced by the circuit.
As we discussed previously, if a battery were left to its own devices it would eventually die as a result of dendrite formation. Unfortunately, heat speeds up most chemical reactions by 2x for every 10℃ rise in temperature.
This means that although it’s theoretically possible to instantly charge a lithium-ion battery, the heat generated by the circuit would expedite the dendrite formation process by a factor of 100–1000x within a couple of minutes.
For this reason, manufacturers explicitly embed monitoring technology within lithium-ion batteries to prevent fast charging, allowing a much longer shelf life.
Existing Solutions
With all the important challenges covered, let’s go over the existing solutions and their gaps preventing mass entry.
Lithium-nickel
Last year (July 2020), in an attempt to assist in the transition of fossil fuels to clean energy, researchers at the University of Texas assembled together to tackle the cost issue of lithium-ions batteries.
While far from perfect, the result was pretty incredible. The major design choice that differentiated the battery from the status-quo was its selected cathode material. Instead of a conventional NMC (nickel manganese cobalt) cathode, the researchers decided to use a revolutionary NMA cathode comprised of 80% nickel and traces of manganese and aluminum.
The absence of cobalt allows the battery to be significantly cheaper, without sacrificing on battery performance. So much so, that Tesla’s currently using a proprietary variation of the battery (however it still contains 3% cobalt) that boasts 50% cheaper costs compared to conventional lithium-ion batteries.
Unfortunately, there’s still a long way to go for lithium-nickel. The battery simply doesn’t meet our performance needs. In spite of 60% improvements in contrast to status-quo lithium-ion batteries, the battery is still insufficient when it comes to energy density. We need substantially better energy capacities in order to make batteries more commercially viable than gasoline engines — and this just doesn’t cut it.
Lithium-air
Perhaps the most promising battery theoretically; lithium-air batteries use an oxygen cathode that’s significantly cheaper than cobalt, and monumentally more powerful. The results vary across experiments, but most yield an energy density of ≥13,500 Wh/kg — 52x more powerful than Tesla’s batteries and more commercially viable than gasoline.
For this reason, tons of research is being conducted to harness its potential benefits. The task has proven difficult in practical application due to previously inconceivable complications.
The most prevalent is electrolyte decomposition. The oxygen reduction process in the cathode leads to the formation of Li₂O₂ and the oxygen radical anion O₂, a highly reactive base that readily decomposes most electrolytes.
As a result, most of lithium-air battery effort has been directed towards finding a stable electrolyte. Unfortunately, all electrolytes tested are either limited by overpressure, cost or thermal dependence. The discovery of an electrolyte material unbound by these limitations could literally change the world forever.
Solid-State
Definitely the most innovative of the bunch; sold-state batteries use a solid electrolyte/separator. They’re manufactured without an anode — and instead serve as collapsible space.
The lack of an anode allows for the highest energy density possible. When the battery is charging, the lithium ions will travel through the ceramic separator and “create” in effect the anode just by taking up space. This results in what’s called a pure lithium anode, consisting solely of the lithium ions and nothing else.
In addition to radically improving energy density, solid-state batteries allow for safer, faster-charging batteries. As we discussed previously, the combustion point of the electrolyte fluid is the limiting factor in status-quo lithium-ion batteries — preventing faster charging and catalyzing explosions.
Due to the fact that the electrolyte is made out of solid, inorganic compounds, the combustion point is noticeably higher. This means that batteries can endure higher temperatures before suffering from performance bottlenecks, or ending in fiery explosions.
Finally, as mentioned previously, solid-state batteries don’t have a dedicated anode. This means that no dendrites can be formed in the [nonexistent] solid-electrolyte interphase, allowing solid-state batteries to have lifespans that meet commercial viability requirements.
An exciting future
If we integrate the elements of solid state design with lithium-air cathodes, the opportunities would be truly limitless. The unstoppable performance of lithium-air combined with the safety and energy density of solid-state would truly be unrivalled. Investing early in the manufacturing of these cells could pay enormous dividends in the future.
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