Evolving battery technology will alter demand for raw materials

Evolving battery technology will alter demand for raw materials

Ahead of the S&P Global Platts Global Metals Awards in London, on May 16, The Barrel presents a special series of articles looking at the global metals trade. Emmanuel Latham and Felix Maire take a look at how changing battery chemistries will affect markets for metals like cobalt, nickel and lithium.

As the automotive sector hits difficult times, electric vehicles are proving to be one area in which horizons seem bright.

Global light duty plug-in electric vehicles were up 43% year on year in February as depicted in the latest Platts Analytics EV Essentials data, and several carmakers are increasing their commitment to the electrification of passenger vehicles.

 

As these commitments grow, the raw materials that underpin the EV industry are subject to greater scrutiny. Lithium, cobalt and nickel are all key components of the current cathode technology, NMC. Both lithium and cobalt have seen the landscape of their markets rewritten by the newfound demand, while nickel, the only one of the new ”battery metals” whose major demand base is not batteries, looks set to experience some supply shortages going forward.

Consumer demand and favorable Chinese subsidies have seen the battery industry pushing towards increased ranges in recent years, while cobalt’s price movements over 2018 and unreliable supply origins have seen moves to reduce cobalt content in cathodes.

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Fortunately thanks to advances in NMC technology, increasing range and reducing reliance on cobalt go hand in hand for battery makers. The dependence of the global cobalt supply on the Democratic Republic of Congo, has encouraged battery makers to look into alternative technologies that limit their exposure to the metal. The unpredictability of doing business in the DRC has caused difficulties for the battery industry. For instance in December 2018 the country classed cobalt as a “strategic” substance, nearly tripled royalty payments, ramping up costs for producers based there.

The DRC’s artisanal mining industry is also a factor behind battery makers and EV manufacturers’ attempts to reduce cobalt consumption. According to Amnesty International some artisanal operations in the DRC have children working in hand-dug mines and facing serious health risks as a result. Given this situation, it comes as little surprise that international companies would like to limit cobalt use, although it is worth noting that according to one major producer, the lower prices of cobalt hydroxide in 2019 have heavily disincentivized, and thus reduced, artisanal activity so far.

Higher nickel, lower cobalt batteries such as the NMC 811 are widely considered the future, using three times less cobalt than the existing NMC 111. Despite expectations that the cobalt quantity per battery will fall, overall cobalt demand (from passenger vehicles) is expected grow, according to S&P Global Platts Analytics.

Go deeper: S&P Global Platts Analytics Scenario Planning service and EV Essentials data

While it only forms a small portion of present nickel demand, growth from the battery sector is expected to outstrip that of other demand bases. As NMC cathode technology moves towards higher nickel content, demand per battery is set to grow. Compounded with anticipated increases in stainless steel and alloy industries and the lack of fresh nickel supply coming online, this has led to widespread expectations of a supply crunch.

HPAL production from Indonesia could well prove the answer. Tingshan Group announced in 2018 plans to build a high pressure acid leaching plant (for nickel extraction from laterite ore) in Indonesia by 2020. Other HPAL projects in the country could also be on the horizon. Also feeling the impact of the push towards higher nickel NMC cathodes is the lithium industry. Earlier cathode technologies used lithium carbonate, but for NMCs with over 60% nickel content, lithium hydroxide is proving essential. Synthesizing higher-nickel content cathodes with lithium carbonate requires high temperatures, which damage the crystal structure of the cathode. With hydroxide, the synthesis can occur rapidly at lower temperatures, maintaining battery performance.

Despite the increased demand and attention, hydroxide prices have trended down over the year, narrowing the spread to carbonate, and some market expectation was seen that the spread could narrow to merely the cost of conversion between the two products, but this is yet to be seen. Major producers are targeting hydroxide expansions through 2019, with Albemarle leading the charge, by commissioning an additional 20,000 mt of capacity to their Xinyu hydroxide plant in China.

Carbonate remains the most heavily traded product, but with increased production and inquiries, hydroxide is gaining ground. However, changes to Chinese subsidies for electric vehicles, announced March 26 could change market direction. The new measures have slashed the subsidy for vehicles with ranges over 400 km by half, and increasing the range required for any subsidy to be paid at all, prompting worries that cathode technology progression could stall.

Despite being widely anticipated by the market, some lithium hydroxide producers fear that the subsidy cuts could hinder demand, with murmurings that some projects have been postponed on the announcement. The announcements have also created some anticipation that cheaper but more rudimentary cathodes, such as Lithium Manganese Oxide and Lithium Iron Phosphate might see increased production, which would improve demand for industrial grade lithium carbonate.

Nevertheless, in the longer term, as the market becomes more consumer-driven, increases in EV ranges look inevitable, and with them hydroxide demand growth: as one precursor producer put it, when making cathodes, “Hydroxide is always better”.

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Graphite lithium-ion batteries get a boost from halogen intercalation

Lithium ion batteries are a useful and powerful energy storage option. Commonly used in products ranging from portable electronics to hybrid and electric cars, these batteries show high overall stability and are low maintenance. Lithium ion batteries also display higher charge storage densities and voltages and consistently out-perform typical lead-acid batteries, as the small lithium-ions can pack densely into the anode material.

To further improve battery performance, researchers Chongyin Yang and Ji Chen with co-workers under the direction of Chunsheng Wang at University of Maryland developed a novel graphite lithium ion battery that utilizes high density helper ion packing and a unique water-in-salt electrolyte to achieve a potential of over 4 volts in aqueous batteries. The aqueous nature of their battery is also an advantage, because as the researchers highlight in their report, the intercalation of the helper ions within a water environment “comes with intrinsic safety and environment insensitivity.”

Ions in close quarters

Graphite, stacked layers of the two-dimensional nanomaterial graphene, excels as a battery anode material, particularly in lithium ion batteries where ion packing directly correlates to battery performance. Graphite has a high capacity of 372 mAhg-1 for lithium ions in between its graphene layers. Polyhalogen ions can also insert themselves into the graphite.

University of Maryland has collaborated with Army Research Lab on water-in-salt electrolyte batteries for several years. As a result Yang and Chen et al. were able to use graphite’s advantages along with helper halide ions to achieve a “densely packed stage-I graphite intercalation compound, C3.5[Br0.5Cl0.5].” Specifically, they designed an electrode containing lithium and the helper halide ions. When exposed to the aqueous electrolyte solution and charged, the halide ions give up electrons and lithium ions travel through the battery to the cathode, a favorable reaction that generates a useful current. The helper halides then intercalate into the graphite. This insertion stabilizes the halogens and makes the entire process energetically favorable.

An excellent battery that goes and goes and goes

This helper halide insertion process is very reversible, meaning the battery can be recharged and used multiple times without a major loss in performance. Yang and Chen et al. measured battery performance over usage to find a typical capacity of 243 mAhg-1 with an average voltage of 4.2 V, and 74% of this capacity was retained over 150 battery cycles, meaning battery performance remained consistent over usage. Impressively, this novel battery displayed an energy density of 460 Whkg-1 at material level. For comparison, lead-acid batteries show energy densities around 40 Whkg-1 and leading lithium ion batteries display values near 350 Whkg-1.

Reversible packing

A key component of this consistency and excellent performance is the reversibility of the helper ion intercalation. By using extensive Raman spectroscopy, Yang and Chen et al. show that the helper halide ions pack into the graphite instead of absorbing onto the outside graphite surface. This allows more ions to intercalate, meaning more lithium ions are free to move across the cell and generate a useful current. Upon charging, lithium ions move back across the cell and recombine with the helper halide ions, as released from the graphite.

Additional X-ray diffraction and absorption data show optimal close-packing within graphite occurs when the chloride and bromide ions alternate, which was also confirmed using density functional theory calculations. This implies both halide helpers are required to make the lithium ion movement across the battery favorable. Additionally, without the graphite present to stabilize the ions post-electron loss, the halides may gas off.

Yang and Chen et al. hope this novel battery design will eliminate previous flammability issues with lithium ion batteries while also offering “an energy-dense concept for a future battery that is cost-effective, safe, and flexible.”

 

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