Advancing Energy Storage through LiMn₁₋ₓFeₓPO₄ Cathodes: Critical Material Innovation for Sustainable Lithium-Ion Batteries
Chanmonirath (Michael) Chak (UNC-Charlotte)
LiMn₀.₆Fe₀.₄PO₄ (LMFP) is emerging as a high-energy, cost-effective alternative to LiFePO₄ (LFP) and cobalt-rich layered oxide cathodes in lithium-ion batteries. With LFP demand exceeding 500,000 tons annually, LMFP offers higher operating voltage and enhanced safety without reliance on nickel and cobalt. This study evaluates the impact of electrolyte additives, specifically 2% vinylene carbonate (VC) and 1% ethylene sulfate (DTD), on LMFP performance in pouch cells. Electrochemical impedance spectroscopy (EIS), gas evolution, and X-ray absorption spectroscopy reveal that the VC+DTD combination outperforms single-additive systems, reducing parasitic reactions and impedance while improving coulombic efficiency and capacity retention. After 600 cycles at C/3 and 40°C, the cells achieved 86% capacity retention. This research supports the clean energy transition by offering a sustainable, high-performance alternative, aligning with the symposium’s focus on energy materials, sustainability, and resilient critical material supply chains.
The Fate of Lithium in Pedogenesis above Spodumene-rich Pegmatites at Carolina Tin-Spodumene Belt, North Carolina, USA
Louis Lu (Duke University), Daniel D. Richter(Duke University), Leon Kelly (Duke University), Mike S. Mason (formerly at Piedmont Lithium Inc.), Anselme Dossou (Duke University), Adam C. Curry (North Carolina State University), and Russell S. Harmon (North Carolina State University)
The Carolina Tin-Spodumene Belt (CTSB) bears one of the largest pegmatite-lithium deposits in North America, with on-going exploration efforts giving potential for supplying the ever-rising Li demand. Li enrichment in soils throughout the CTSB (~100 to ~2500 mg/kg) have been reported in contrast to the mean Li concentration in regional and national soils (< 30 mg/kg). Signals of elevated Li in surficial soils and their observed spatial correlation with Li-rich pegmatites at depth could serve as a tracer for detecting dikes of mining interest. To better understand the origin of the elevated soil Li concentrations and refine future modelling and prediction of Li-rich pegmatites, this research aims to 1) investigate Li distributions in regolith and soils both vertically and spatially at a landscape scale; 2) identify retention and loss mechanisms of Li during weathering and pedogenesis and quantify different soil Li reservoirs (e.g. adsorbed on exchange sites, bound to oxides, retained in mineral structures).
Preliminary data from hand-augered 5-m soil cores showed significant Li enrichment both above-dike and in surrounding areas. A mass balance (τ) analysis to ~25 m illustrated a consistent pattern of substantial Li loss up towards ~8 m, above which a rebound of τ might result from accelerated weathering of the more resistant minerals in the shallower soil and saprolites. X-ray diffraction indicated quartz, muscovite and secondary clays (illite and kaolinite groups) are principal mineral phases in the Li-rich saprolite and surface soils. Despite the measured Li concentrations, no spodumene peaks were detected, suggesting almost complete weathering of this primary Li-bearing pyroxene. Little Li was found to be on the exchange sites or bound to the Fe/Mn oxides throughout the 0-5 m deep cores (totaling < 2.5% of total Li), pointing to primary and secondary minerals as major soil Li reservoirs.
Geopolitics of the Critical Minerals Supply Chain
Kyle Beardsley (Duke University), Clara Park (Duke University), Pei-Yu Wei (Dartmouth College)
The potential Chinese actions on Taiwan and the response of the U.S. and its allies could affect the commodity trade networks of critical minerals. Due to the wide reach of the global value chain of critical minerals, disruptions in the network will have large spillover effects in economies from Asia to Eastern Europe, Latin America, and Africa. We conducted a network analysis of four critical minerals essential in the clean energy transition – rare earth elements, cobalt, lithium, and nickel – using trade data to further examine China’s position in the critical mineral trade networks. We especially examined the top exporters and importers of these critical minerals, trading hubs in the network, such as well-connected countries in the global value chain, and countries with very few alternative suppliers other than China. This analysis identifies productive IT manufacturers that would suffer production disruptions in the global value chain as well as near-isolated countries that would lose access to these critical minerals should China be removed from the trade network (e.g., through sanctions against China and China’s counter-measures). This analysis brings to light important steps that the US and its allies can take to mitigate the anticipated disruptions from a China-Taiwan conflict, with an eye toward building resilience in the clean energy transition, reducing the humanitarian fallout and bolstering deterrence.
Hybrid Organic/Inorganic Electrode Design from Bacterially Precipitated CdS for PEC and Storage Applications
Yaying Feng, Edgard Ngaboyamahina, Katherine E. Marusak, Yangxiaolu Cao, Lingchong You, Jeffrey T. Glass, and Stefan Zauscher
Transition metal (TM) chalcogenides are a group of semiconductor materials with applications that range from antibacterial particles to thin films in energy conversion devices. Significant progress in synthetic biology combined with the benefits of low energy consumption and low toxic waste burden of “green synthesis,” have directed considerable research attention to the biosynthesis of these inorganic materials. Hybrid organic–inorganic compounds are receiving increasing attention for photoelectrochemical (PEC) devices due to their high electron transport efficiency and facile synthesis. Biosynthesis is a potentially low-cost and eco-friendly method to precipitate transition-metal-based semiconductor nanoparticles (NPs) in an organic matrix. In this work, we examine the structure and composition of bacterially precipitated (BAC) cadmium sulfide (CdS) NPs using electron microscopy, and we determine their PEC properties and the energy band structure by electrochemical measurements. In addition, by taking advantage of the organic matrix, which is residual from the biosynthesis process, we fabricate a prototype photocharged capacitor electrode by incorporating the bacterially precipitated CdS with a reduced graphene oxide (RGO) sheet. Our results show that the hydrophilic groups associated with the organic matrix make BAC CdS NPs a potentially useful component of PEC devices with applications for energy conversion and storage.
Impact-Benefit Agreements in Critical Mineral Mining: A Typology and Analysis
Savannah Carr-Wilson (Duke University)
Global demand for the critical minerals used in renewable technologies is expected to soar as countries work to realize a clean energy transition. The world will need new mines to adequately scale up production, which will have environmental, social, and governance (ESG) impacts. Academics and policymakers have expressed concern that ESG risks and an associated lack of social license for projects could disrupt mining, leading to shortages of critical minerals that bottlenecks the energy transition. Impact-benefit agreements (IBAs) – agreements mining companies negotiate with local communities in the area they wish to mine and other stakeholders – deserve our attention as an emerging governance solution. IBAs have the potential to be an effective tool for mitigating project impacts, sharing benefits with communities, and fostering social license. While prior work viewed IBAs as confidential and difficult to study, there is a growing trend towards transparency, as more parties choose to make these agreements public. In this article we collect a novel dataset of 32 public critical mineral mining IBAs from Global North and South countries, pertaining to a range of critical minerals. Building on this dataset and the literature on public and private governance, we propose a typology of mining IBAs, which shows that critical mineral mining IBAs can be characterized as private governance mechanisms, or quasi-public. We apply this typology to characterize the critical mineral IBAs in our dataset, and describe their features. Overall, our article offers researchers and policymakers a conceptual roadmap to understand the different types of IBAs used in critical mineral mining and their features, supporting further empirical investigation into the role these agreements could play in addressing the environmental and human security impacts and building out benefits of critical mineral mining.
Minerva Gen 4 Technology for Climate-Smart Lithium Recovery from Spodumene
Shawn Adams (UNC-Greensboro)
The United States’ vision for a resilient critical materials ecosystem requires a strategic prioritization of energy independence, technological leadership, and economic growth. Sustainability of domestic sources of battery critical materials reduces reliance on foreign supplies and enhances national security, American competitiveness, and economic standing. However, U.S. manufacturing competitiveness is constrained by the lack of robust extraction and processing domestically. There is a bottleneck in the domestic supply chain between raw material production and refining and component manufacturing. In the upstream lithium supply chain, the U.S. has limited domestic production of lithium carbonate equivalent (LCE). Focusing on the upstream and midstream supply chains for lithium, we propose a climate-smart lithium extraction and conversion technology, Minerva Gen 4 technology, to manufacture high-purity LCE from spodumene feedstocks. This innovative approach overcomes the energy-intensive acid roasting step in upstream lithium extraction by employing a green chemistry-based deep eutectic solvent (NDES) approach. Additionally, it eliminates the need for lime-based neutralization and subsequent chemical precipitation in midstream processing.
Mitigating Critical Mineral Dependency through Carbon Nanomaterials: Insights from Carbon Nitride
Andrey E. Rubin, Yash Shah, Leanne M. Gilbertson
Department of Civil and Environmental Engineering, Duke University
The demand for and availability of critical minerals presents an urgent challenge for nations like the United States, which relies heavily on imports from other countries. Using catalyst minerals as an example, 2023 annual production in China (compared with the United States ) is 4,000 metric tonnes of zinc (versus 750 in the U.S.), 3,400 metric tonnes of silver (versus 1,000 in the U.S.), and gold reserves of 12,000 metric tonnes in Australia (versus 3,000 in the U.S.).1 This highlights the potential for alternative materials to aid in reducing dependency on critical minerals.
Our group synthesizes graphitic carbon nitride (g-C₃N₄), a polymeric carbon-based nanomaterial and demonstrates its use for environmental catalysis. Energy related applications include water splitting (substituting minerals like platinum, Pt), carbon dioxide conversion (replacing, transition metals such as zinc, Zn), as well as H2 production (replacing gold, Au, and silver, Ag). One of the key benefits of g-C₃N₄ is its low-cost, facile synthesis from abundant precursors like urea and melamine, making it suitable for large-scale applications. Further, g-C3N4 possesses an optical band gap that allows for visible light absorption, enabling activation from lower energy, lower cost incident light compared with high energy, higher-cost ultraviolet light sources. However, pristine carbon nitride faces intrinsic limitations, including rapid electron-hole recombination, low electronic conductivity, and limited visible light absorption, which restricts its photocatalytic efficiency. To overcome these challenges, our lab has developed advanced strategies, including in situ, non-metal doping with elements like carbon, boron, and oxygen, to improve these physical and chemical properties.
Additionally, we integrate life cycle impact assessment (LCIA) to quantify the environmental impact of g-C3N4 production, benchmarked to the metal alternatives it replaces (e.g., platinum, silver, gold). For mineral-based materials, the impacts of mining and refining processes are immense, even when small quantities (≤ micrograms) are used to obtain the desired function. Using multiple functional units, we “normalize” embodied impacts of g-C3N4 to its performance when comparing to alternatives of interest (e.g., global warming potential per unit hydrogen produced or per unit CO2 converted). Incorporating LCIA during our material development allows us to uncover high impact contributors and inform decision making toward modifying our synthesis to further reduce impacts per unit function gained.
1 Statista database (November 2024), https://www.statista.com/
Rare Earth Elements in Acid Mine Drainage and Treatment Byproducts
Anna Altmann (Duke University)
Acid mine drainage (AMD) is the acidic waste produced from the oxidation of exposed rock during and after the mining process. This waste is harmful to watershed health and wildlife but is costly to clean up. Research suggests AMD wastes can be high in rare earth elements (REE), which are elements that are heavily used in magnets, computers, batteries, and many other industries. The goal of this research was to understand the levels and extractability of REE in AMD to help understand whether cleanup of these wastes can be incentivized by REE extraction. Seven AMD treatment sites in Western Pa with a variety of solution chemistries and treatment types were sampled in June 2024. Influent AMD was analyzed via ICP-MS for REEs and other elements and via IC for major anions. Treatment solids were analyzed via XRD for mineralogy. They were also analyzed for major element composition via ICP-MS after sodium peroxide sintering. Treatment solids were found to be largely amorphous, but typically had distinct quartz and calcite phases. The sites averaged 513.4 ppb influent REE, with a maximum of 1547 and a minimum of 186.7 ppb. The solids were found to be enriched in critical REE, and some had over 1600 mg/kg total REE. Based on these findings, AMD and AMD treatment solids from Western Pa could be a source for REE mining.
Revealing the Coupling Between Anion Redox Reactions and Structure Evolution in Layered Oxide by STEM
Hanyu Fu (Duke University)
The growing demand for rechargeable batteries in electric vehicles and portable devices has triggered extensive efforts on next-gen energy storage materials. Sodium-ion batteries (SIBs) are advantageous for such purposes due to the wide distribution of sodium resources and low cost. Especially, the SIBs loaded with O3-type layered transition metal oxide cathodes (TMOs) are one of the most promising systems due to their excellent rate performance and cycle stability1,2. However, low energy density is the main challenge in applying O3-type SIB for much broader applications. Several strategies can be employed to improve the energy density of SIBs, including applying the anode-free design3, using solid-state electrolytes4, and introducing the anion redox reaction (ARR) on cathodes5, etc. Among them, introducing ARR by increasing charging voltage is one of the most effective approaches. However, high voltage could lead to poor capacity retention and short cycling life5, making it challenging for practical use. Understanding the structural and chemical evolutions and increasing the reversibility of ARR is therefore significant for better SIB design. In previous research, elemental evolution and ARR reversibility have been widely studied through spectroscopy and theoretical methods. For example, TM-ion transitions and oxygen loss are found to be related to irreversible oxygen redox and the subsequent voltage and capacity decay6,7. On the other hand, cathodes with more reversible oxygen redox pathways are designed by structure modulation8, choosing heavier transition metals9 and alkali-ion doping10, etc. In these materials, oxygen anions have multiple pathways with different reversibility to stabilize after oxidation. The oxygen electron holes could be stabilized by forming π-type bonds with TM t2g orbitals8, being localized11 or delocalized12, and forming trapped molecular O213, etc. Interlayer interactions among oxygen anions after sodium deintercalation are also predicted to be related to ARR reversibility14. However, there is little experimental research on how these bonds rearrange spatiotemporally and how the rearrangement is coupled to the lattice structure evolution15. Further, it has been recently found that Li-doping could increase the ARR reversibility of TMOs and suppress performance attenuations16,17. The exact role of Li-ions on the coupling between ARR and structure evolution, is still not clear. We hypothesize that the grain surface atomic arrangements and chemical bonding differ from those in the bulk after electrochemical cycling, and that the influence of Li-doping on the atomic structure and chemistry of the surface and bulk may vary as well. We propose to use scanning transmission electron microscopy (STEM) to test this hypothesis, which allows high-resolution structure and chemical information mapping of cathode materials6,7,18. STEM will be used to investigate the reversibility of ARR at surface and bulk of NLNMT, focusing on understanding how Li-ion doping affects the reversibility of oxygen redox, revealing the coupling mechanism ARR pathways and structural evolution. Results obtained from this work may provide insights into the design of more reversible ARR strategies with improved voltage and capacity retention.
Searching for Alternative Critical Mineral Sources
Gordon Williams, Robert Hill, Zhen Wang, Avner Vengosh
Division of Earth and Climate Sciences, Nicholas School of the Environment, Duke University
The transition from fossil fuels to green energy requires the acquisition of large quantities of critical raw materials (CRMs) such as lithium and rare earth elements to be used in energy infrastructure, batteries, electric cars, and solar panels. Traditional mining of CRMs has largely been limited to specific geological domains in a limited number of countries, thus creating supply shortages and geopolitical constraints for future large-scale production and utilization. Expanding the mining and production of CRMs will inevitably pose environmental, economic, and social justice impacts. Research in Vengosh Lab explores the potential of alternative sources of CRMs through the following projects (1) evaluating the potential of lithium resources in underlying sediments of salt pans (salars) where currently lithium is exclusively extracted from brines; (2) exploring the occurrence and extraction potential of rubidium in worldwide lithium-rich resources (brines from salars, geothermal waters, oilfield brines) and delineating the chemical properties of the different resources for optimizing extraction and separation methods; (3) exploring the potential of rare earth element extraction from phosphate rocks and phosphogypsum waste byproducts. Phosphogypsum is a large-scale waste byproduct generated during phosphate fertilizer production and poses environmental hazards due to the high levels of radium, a radioactive element. Rare earth elements are, however, accumulated in phosphogypsum and given its relatively high of solubility, phosphogypsum could be a potential resource of REE worthy of exploration.
