In the second instalment of our battery article series, we embark on a detailed journey into the world of lithium-ion batteries for wearables, consumer electronics, and especially the EV space, which we defined as battery segments 1, 2 and 3 in the first article. The driver here is mobility, flying, floating, and rolling.
In this article I try to go beyond the surface, unravelling the intricate chemistry of active materials (BAM) and the four main components in the cells.
Lithium-ion batteries – an historical insight
Rechargeable lithium-ion batteries, characterized by their “reversible intercalation in layered compounds,” trace their fascinating roots back to the 1970s. The pioneering work of Jürgen Otto Besenhardt and more recognized, Stanley Whittingham – who back then worked at Exxon – presented the first iteration in 1972.
It took several shots before Whittingham together with Akira Yoshino and John Goodenough got to a commercial product in 1991, produced by Sony and Asahi Kasei. Sony was also the group who coined the term “Lithium-ion” batteries.
Since then, battery volumetric energy density has increased 3 to 8-fold, and the costs have dropped 10-fold. A further doubling of energy density is already visible with current technology, and we should expect to reach 1.000 Wh per Liter in this decade, even in regular lithium-ion batteries.
A similar wild cost dive does not look possible, unless new technologies and constructs are invented, and the use of minerals are significantly reduced. Stanley Whittingham, Yoshino and Goodenough had their work crowned with the 2019 Nobel Prize in Chemistry, but they were (are) not yet satisfied with the performance and security of their product.
“Reversible intercalation” is the technical term for “recharging”, which involves the intricate process where lithium-ions traverse the crystal lattice structure (shelves, see below) during the charging and discharging cycles, showcasing a remarkable reversibility that underpins the functionality of lithium-ion batteries.
Diving into the technicalities. Battery capabilities are explained in Volt, MWh, and C-rate, with power, energy density, charging speed, and of course security being pivotal. The C-rate, denoting the charging rate, adopts a scale where 1 signifies one hour and 4C equates a mere fifteen-minute charging time. The ultimate metric steering battery development is through its energy density / performance measured in Wh per Kg or Wh per Liter, equalling gravitational or volumetric density, and of course the economic factor.
Components of battery cells
Batteries unfold in intricate entities as four major components: the cathode, the electrolyte, the separator, and the anode (as can be seen above), plus the two current collector foils onto which the anode and cathodes are coated.
Design and production processes have been the same for a long time. Newer, better, faster, and thereby more economical processes are implemented, but there is still work to be done, which I will return to in a later article.
Lithium-ion batteries: Cathodes
The cathode has received most of the attention in terms of research and debate, until solid-state batteries became a thing. The cathode is manifested in various formulations, chemistries, and their crystalline structures. The metal oxides like cobalt, nickel, manganese, aluminium, iron, phosphor etc, make up the formulations, the chemistries, the Cathode Active Materials (CAMs).
There are also binders and conductive additives, residuals that needs to be minimized because they only bring counterproductive factors like extra weight and friction into the equation. This is probably one of the biggest challenges and potential gains that can be achieved in future constructs.
First, we saw the development of cobalt-based LCO chemistry, which is still predominant in consumer electronics like phones and computers. Then “ternary” formulations with nickel, manganese, cobalt, and/or aluminium entered the scene.
Different developments firstly reduced the content of cobalt, and recently nickel also have been reduced, substituted by the LMP chemistry, all in the name of security, price, social, and supply concerns.
In the end, the safety advantages of cobalt and the energy density of nickel should not be neglected, and at least get Nickel back into the limelight, unless Manganese can take its place. Manganese has been tried in multiple formulations and formats, but it has never been stable enough, but it looks as if that is changing and Manganese could get its rival here in 2023-24 in new forms, either with doped LFP or with LMNO or other formulations.
The Lithium Ferro (iron) Phosphate formulation (LFP) has emerged as a safety-conscious alternative, gaining traction particularly in China, where regulatory compliance drove its initial adoption in public buses and taxis because of its impressive chemical and temperature stability, and recently with its ultra-fast charging capabilities.
The evolving landscape here has driven the emergence and migration towards LMFP, marking a smaller shift in formulation with a significant advancement in energy density of 25-30%, on already active manufacturing lines, with only a 5% price impact, through “simple” manganese doping and other processes.
It is a significant advancement, and why it can be expected that we will see all LMP production migrating onto LMFP in the coming years. Further to that, manganese formulations like LMO, and more prominently LMNO could be providing manganese and nickel with something of a renaissance. Nothing beats nickel in energy density, yet, but popularity always has to be weighted through the optics of security and price.
The LFP or LNFP doped chemistries look to be the benchmark that needs to be beaten going forward in terms of charging speed and safety. When it comes to energy density, the Ternary 811 NMC version is still ahead, but other formulations are seeking to dethrone it.
- Green tech venture Nano One Materials reports net assets now north of C$25 million
- Nano One continuing to benefit from Canadian government funding
- Lithium carbonate market: will increased supply in Q2 drive spot price down?
Lithium-ion batteries: Anodes
The role of graphite in anodes, both natural and synthetic, is paramount today. Natural graphite, with its higher porosity demonstrates advantages, yet brings challenges such as swelling and reduced predictability, especially with capacity tuned silicon doping versions. The ongoing development points towards alternative anode materials like silicon and/or lithium, as the industry strives for higher energy density and power, especially in performance-driven segments like wearables, consumer electronics, sports cars, and aeronautics.
Today anodes are the largest limitation on energy density in lithium-ion batteries, which is why it is becoming an investment theme, especially in the area of solid-state batteries where lithium drive anodes are taking over. In next and again, next level cells, the philosophy around “anode-less” batteries are becoming more established, a solution presented by QuantumScape. Remember the part that is not there is the best part. There is more to come on this intriguing theme.
Lithium-ion batteries: Separators
The separator is critical in ensuring cell safety and its trade-off of ion transfer speed between the electrodes. The separator is the thin, porous membrane in the middle of the cell that physically separates the physical contact of the anode and cathode materials, while facilitating isolated ion transport in between the anode and cathode in the cell.
The thermal runaway happens when this barrier is broken, and the different electrode materials come into contact with each other. The intricacies of separators highly influence key battery capabilities such as MWh and C-rates (charging speed).
Lithium-ion batteries: Electrolyte
The liquid electrolyte’s role in ensuring safe battery operation and ion movement necessitates ongoing improvements. Advancements in electrolyte formulations does not get much attention, but good things are happening there, in advancing the effective transfer of ions without failure and dendritic growth. Failure here will result in cell collapse. New formulations like Bis (FluoroSulfonyl)Imide (L iFSI), promise enhanced performance over traditional Lithium HexafluoroPhosphate (LiPF6), the current most popular solution. These changes are delivering an impressive additional 10% in terms of extra efficiency.
Other and even better electrolytes are on the horizon, but the big change here will be the solid-state electrolyte and cells. The migration through semi-solid, quasi-solid, to all-solid-state batteries will mark a significant shift in battery technology.
Here a new world of electrolyte formulations will arrive, securing better ion transfer with higher thermal stability, and must prevent dendrite growth. The latest version visible here has interesting names like LLZO (Li7La3Zr2O12), Ceramics such as lithium thosilicate, glass, sulphides, oxide solid electrolytes, perovskite-type, and garnet-type (LLZO) with metallic lithium. We are talking advanced physics and chemistry here.
Solid-state battery cells
As could be understood from above, solid-state refers to the electrolyte. The transition towards solid-state cells is not a binary process in my opinion. It will happen stepwise, and already we are now hearing about hybrid “All-Most” solid-state solutions before we transition to “All Solid-state” batteries. The journey here should bring another 30-50% advancing in energy density against weight and volume.
All-Most hybrid solid-state cells termed Semi-Solid, Quasi-solid, are today qualifying with test samples in automotive, consumer electronics, and aeronautic cell costumers.
A recent publication by BMW, where SolidPower delivered their first test sample, lets BMW proclaim it will be in their vehicles by 2025. Prior announcements in this field from Toyota and their former CEO, have evidenced massive frustration, with him dismissing batteries and maintaining his support for Hydrogen H2. As said before, this is serious science and solutions are not defined and implemented overnight.
This migration towards solid-state cells with lithium metal or lithium alloy metal anodes, if any anode material, will not happen as one giant leap for mankind, as said above, and as it is hoped for by many automotive managers. It will be a gradual process in various ways on each of the four components.
And then the next step – the “Anode Less” battery cell. In this design there is no anode or only very little anode material. As the name implies (badly), the dedicated anode material is not there, but the function of the anode is. This idea was first published by QuantumScape.
As can be understood, progress seems guaranteed within battery cells over the next many years, but the arrival of these fantastic products at the consumer level is still an open question in terms of time estimates; hopefully it will be within our current decade. The reach could be considerable, migrating into many other industries, and driving along a new revolution in material science.
Final thoughts on the battery materials sector
In examining the global battery manufacturing landscape, it’s evident that European, Japanese, North American battery and automotive companies face challenges in translating their businesses and implement these technical insights into tangible products. Despite their head start, Chinese and Korean battery cell companies dominate both the near-term manufacturing and partially also the technological frontier with new cell products ready or at least those that are visible.
The rush towards solid-state batteries, most notably among German luxury car manufactures, and European and US technology companies, opens the question over whether the leapfrogging strategy passing the first generation of EV batteries will work? The jury is still out here!
As I mentioned above, solid-state batteries seem to develop in steps and not in one giant leap, which is why their strategy could turn out to be fatal. One argument that can be understood is their strategy towards the pouch cell format, which looks to be the format for solid-state cells. The strategy, I imagine, is constructed around their hope that the solid-state pouch cells can be integrated into their current body works. Again, this might be a dangerous way forward.
In the end, no matter what properties an object has, when it comes to mass market products, price will be the ultimate determining factor for mass markets, which here translates into Wh per $.
Our third and final article in this series will look at the cell formats and integration into cars, a domain where Tesla is reshaping the entire paradigm of car construction and propulsion.
Tesla’s innovative approach with a central chassis carrying the cells and the giga-casted fronts and rears, plus their next up “un-boxing” of the bodywork, challenges the legacy car of manufacturers. The economics, weight, and flexibility advantages of the Tesla approach looks to be unparalleled, leading to car-industry changes on technical and manufacturing levels, that are even outpacing and out-scaling Henry Ford’s assembly line and speedy mass production process. Some companies will be left behind for extinction.
Henrik Mikkelsen is a Strategist, Investment Advisor and Business Developer with Iridis AG, an investment management and corporate advisory firm in Zug, Switzerland. Henrik has more than 30 years of experience from investment banking and commodity trading, running strategies for clients and himself, as well as writing about markets and giving lectures on technical analysis and risk management.
