Sodium-ion battery technology is becoming a real alternative to lithium-ion
Lithium-ion batteries have led the market in electric vehicles (EV) since the inception of this category of vehicle. But lithium-based cell chemistries are not the industry for batteries in the medium or long term. Price, safety, sustainability, and ethical considerations limit its future growth. This article looks at how Sodium-ion batteries are emerging as a real alternative and are set to become increasingly important in the coming years.
As electric vehicles become increasingly popular, prices for key battery ingredients, particularly cobalt, have spiked. That has spurred car and battery makers to seek alternatives to the current three main technologies – nickel-cobalt-aluminium (NCA), nickel-cobalt-manganese (NMC) and lithium iron phosphate (LFP) batteries.
The reason why such batteries cost a lot is because of two key reasons: high cost of lithium resources and high cost of cobalt used in the NMC cathode.
Lithium is a scarce element in the earth’s crust. Cobalt supplies are also finite, and most of its production occurs as a by-product of other minerals’ production. This means that the supply and price of cobalt will be highly dependent on the demand for other elements – which is not good for price security.
On the other hand, sodium is the sixth-most abundant element on earth. Not only is it prevalent, it is easy to extract and no one country dominates the global value chain. Bill of materials and cell costs for this battery chemistry are 24% lower than LFP cells.
The dangers of transporting Li-ion batteries are well documented, and they cannot be discharged below 30% SOC, so cargo cells must be air-freight transported at considerable cost.
However, a Sodium-ion cell can be fully discharged to zero volts, akin to a capacitor. In this state, the potential for thermal runaway due to short-circuiting is eliminated. The Sodium-ion electrolyte NaPF6 in PC, in combination with a hard carbon anode, releases energy at a temperature 90 degrees celsius above that of the Li-ion electrolyte, LiPF6 in EC-DMC with a graphite anode.
The dominant forms of lithium production can be from brine (led by South American countries such as Chile) or mined from minerals where Australia is the leading producer. Most cobalt reserves are located in the geo-politically sensitive Democratic Republic of Congo, where child labour could be a significant input.
In addition, China controls much of the global value chain. From a geo-political perspective, an economy may move away from a dependency on Middle Eastern oil to batteries from China.
Lithium mining also requires huge amounts of groundwater to pump out brines from drilled wells. Nearly two million litres of water are needed to produce one ton of lithium – that’s enough only for about 90 cars. As climate change intensifies, plentiful groundwater supplies will come at a premium.
Sodium-ion is catching up
Research interest in Na-ion batteries has really taken off since 2011 when the scientific community realised scarcity in lithium reserves was a fatal flaw inherent to Li-ion batteries. Until 2010, there were only 115 scientific papers ever published on such batteries. In the subsequent nine years, this number grew 50-fold, to 5,804, and it has grown even more since.
Faradion is based in Sheffield and is at the forefront of global innovation in Na-ion batteries. We have now developed a strategic, wide-reaching, and extensive IP portfolio of 30 patent families including for cathode and abode material, safety, and pack, as well as process. The majority of our IP is core state of matter, which is highly defensible. This makes our portfolio incredibly strong compared to other major companies in this space.
Faradion’s batteries already boast performance as good as Lithium Iron Phosphate (LFP) batteries at 150-160 Wh/kg. At the 100Ah pouch-cell scale, we project reaching 200Wh/kg later this year, which is the same as what Chinese battery manufacturer CATL is targeting.
Our Na-ion cells are an excellent drop-in replacement for lead-acid batteries for low cost electric transport – in LSEVs, e-scooters or as batteries for e-rickshaws and e-bikes – offering much greater range and carrying capacity for a similar price.
They also have potential for the S-L-I (starter-lighting-ignition) 12V battery or the 48V battery in a MHEV (mild hybrid electric vehicle). This is because Na-ion has higher energy density than lead acid batteries, as well as improved performance over a wide temperature range.
Finding an alternative to graphite
Carbon, in the form of graphite, works well as an anode material in Li-ion batteries, but it is electrochemically less active towards sodium. So one area that needs more attention is the development of new anode electrode materials, particularly for Na-ion batteries.
In our patent granted earlier this year, we take carbon-containing starting materials from animal-derived material (including animal faeces but also skin, bone, hair and more) and process it into hard carbon for use in our anodes.
We also launched a technical collaboration earlier this year with energy manufacturing company Phillips 66 to develop lower-cost and higher-performing anode materials for Na-ion batteries. Research and development will be conducted in Oxford, Sheffield, Oklahoma, and Houston.
CATL enters the market for Sodium-ion
CATL recently unveiled a Na-ion battery, saying it planned to set up a supply chain for the new technology in 2023. Given it is China’s top car battery maker with a market value of almost $200 billion, it is big news for the cell chemistry. It shows there is a momentum behind technologies beyond lithium, particularly when China is reliant on imports for over 80% of its lithium.
Nissan’s gigafactory announcement
In the lead up to COP26 in Glasgow this year, it is important for the UK to be seen as leading the world in using innovative solutions to combat climate change. Nissan’s new investment serves to highlight the UK automotive industry’s commitment to net zero. Investment in cathode/anode production, cell manufacturing and application can create huge economic benefits for the country, including adding thousands of new green jobs and billions to GDP.
Nissan’s existing facility of 1.9GW is already Europe’s largest gigafactory. With Chinese company Envision’s expansion, the new site will add 6.5GW.
From Faradion’s perspective, since the manufacturing process of Na-ion and Li-ion batteries is identical, including all equipment, it provides an exciting opportunity for Faradion’s technology to be used in existing lithium-ion manufacturing processes. The window is currently open for a country or region to create Sodium-ion supply-chain clusters to take the lead in Sodium-ion battery manufacturing as was done by Japan initially in the 1990s followed by South Korea and China for Li-ion cell manufacturing.
The Faraday Institute recently published a report that outlined the scale of the opportunity for the UK to become a global leader in next-generation battery technology.
The roadmap for Sodium-ion
A recent paper in the Journal of Physics: Energy laid out inputs from The Faraday Institution, Lancaster University, Faradion, STFC Rutherford Appleton Laboratory, University of Oxford, University of St Andrews, University of Sheffield, Université de Nantes, Diamond Light Source, UCL and others on how they see the future roadmap for Na-ion technology.
It says that the current generation of these batteries, if advanced to mass production, can be competitive against LFP (and replace Pb-Acid) and NMC cells for stationary and telecoms applications.
The current generation of NIBs has the potential to make big improvements in their energy density through electrode and cell design optimisation. Compared to LIBs, the NIB anode and cathode spaces are relatively unmined, so there is still significant potential to further increase the energy density of second-generation NIBs to 190 Wh/kg and beyond.
In other words, while micro-improvements in Li-ion cell chemistry are being made each year, Na-ion has the runway to make meaningful improvements in density and cycle rate year-on-year for several years still.
Tesla’s Model 3 already includes LFP cathodes made by CATL, in a bid to save nickel-based cells for applications like the Semi. Volkswagen has said it wants to cut the price of its entry-level models by half by using LFP. Because LFP batteries don’t use scarce and high-priced nickel or cobalt but instead the abundant and cheap iron and phosphate, switching the metallic cathode inputs presents a powerful cost saving.
As LFP enters this battery space, Na-ion will grow increasingly important too because it has no lithium.
Nevertheless, it is not an either-or situation. For different applications, different technologies will be most appropriate. The big message from recent developments is that there are now real alternatives to Li-ion, which makes the battery industry an incredibly dynamic and interesting space to be in.
Dr Ruth Sayers is Operations Manager at Faradion