Li Sources Research Articles

Li–Na-based hybrid battery

Li battery has been widely used in mobile electronic devices such as mobile phones and laptop computers and is currently expected as a power source for electric vehicles. Due to high cost and limited supply of Li sources, post-Li batteries like Na, K, Mg and Zn batteries have been researched intensively. However, the post-Li batteries face issues of low-energy density in monovalent ion (Na, K) batteries and slow ion diffusion in multivalent ion (Mg, Zn) batteries. The hybrid metal ion battery (HMIB) contains two different cations which can combine the benefits of fast ion diffusion of monovalent ions and high capacity of multivalent ions. Various types of HMIBs such as Na–Mg, Li–Mg, Li–Zn and so on have been studied. Among them, Li–Na HMIBs composed of Li-based cathodes and Na metal anode are the most promising as the post-Li battery owing to the application of matured Li technology and electrochemical/chemical similarity of Li to Na. In addition, dendric deposition of Na metal is suppressed by the shielding effect, allowing to employ Na metal anode in the Li–Na HMIB system. Na metal anode can provide higher capacity and reduce the material cost. Additionally, commercial Li cathode does not require further investment for manufacturing cathode materials, resulting in a significant reduction of development cost and rapid commercialization of the Li–Na HMIBs. Thus, in this review article, studies on the Li–Na HMIBs are summarized and analyzed, then future challenges for the development of Li–Na HMIBs are suggested.

Lithium and strontium isotopic systematics in the Nalenggele River catchment of Qaidam basin, China: Quantifying contributions to lithium brines and deciphering lithium behavior in hydrological processes

The salt lakes fed by the Nalenggele River in the Qaidam Basin, located on the northeastern Qinghai Tibetan Plateau (QTP), are major brine lithium reservoirs in China. The quantitative identifications of the Li sources and their dynamic behavior shed light on the formation mechanism of the brine Li deposits in closed-basin of arid regions. This study presents Li and Sr isotope ratios (δ7Li, 87Sr/86Sr) and other hydrogeochemical parameters for river waters, springs, spring river waters, shallow groundwaters, surface brines, and intercrystalline brines around the Nalenggele River Basin (NRB) and its adjacent small watersheds. The results indicate that the Nalenggele River water is a mixing product of hot springs and regional surface meltwater, and the source of dissolved Li in the NRB is mainly supplied by the hot springs. With multi-tracer models, it is confirmed that around 84.9 %−93.4 % of dissolved Li is provided by the Li-rich hot spring waters, which account for only 3–5 % of the total water input. Furthermore, the dissolved Li in the streams of different hydrological regions shows various isotopic fractionation behavior. In general, the lower average δ7Li values (average of +5.6 ‰) with more enriched Li with respect to Na in the waters of the piedmont Gobi region indicates a significant additional input of dissolved Li from bedrock and sediments. The second-stage alluvial fan of the NRB produces 7Li enrichments and Li-depleted waters (compared with Na), which can be explained by the adsorption of clay or Fe (Mn) oxide phases that fractionate Li isotopes. The highest average δ7Li values (+12.76 ‰) are observed when Li is not adsorbed by the scarce fine clastic sediments in the hypersaline environment of the salt lake region. It can be concluded that the continuous halite precipitation during the brine evolution not only causes the abnormal enrichment of Li in the brine (compared with Na) but also continuously sequesters the 6Li from the brines, resulting in a significant 7Li enrichment. Overall, these findings advance the understanding of the lithium sources of Li-rich brines and its enrichment and metallogenic process during water migration in hyper-arid regions and have crucial indicative significance for lithium cycling under a strong evaporation environment.

Understanding the Fluorination of Disordered Rocksalt Cathodes through Rational Exploration of Synthesis Pathways

We have designed and tested several synthesis routes targeting a highly fluorinated disordered rocksalt (DRX) cathode, Li1.2Mn0.4Ti0.4O1.6F0.4, with each route rationalized by thermochemical analysis. Precursor combinations were screened to raise the F chemical potential and avoid the formation of LiF, which inhibits fluorination of the targeted DRX phase. MnF2 was used as a reactive source of F, and Li6MnO4, LiMnO2, and Li2Mn0.33Ti0.66O3 were tested as alternative Li sources. Each synthesis procedure was monitored using a multi-modal suite of characterization techniques including X-ray diffraction, nuclear magnetic resonance, thermogravimetric analysis, and differential scanning calorimetry. From the resulting data, we advance the understanding of oxyfluoride synthesis by outlining the key factors limiting F solubility. At low temperatures, MnF2 consistently reacts with the Li source to form LiF as an intermediate phase, thereby trapping F in strong Li–F bonds. LiF can react with Li2TiO3 to form a highly lithiated and fluorinated DRX (Li3TiO3F); however, MnO is not easily incorporated into this DRX phase. Although higher temperatures typically increase solubility, the volatility of LiF above its melting point (848 °C) inhibits fluorination of the DRX phase. Based on these findings, metastable synthesis techniques are suggested for future work on DRX fluorination.

Boron and lithium behaviour in river waters under semiarid climatic conditions

Boron (B) and Lithium (Li) concentrations were studied in the Platani river, one of the most important catchments of South-Central Sicily which is under semiarid climatic conditions for roughly eight months to a year. In this area, evaporites result in potential B and Li sources for surface waters. Results from river waters have measured ionic strength values between 0.1 and 4.54 M. B and Li distributions in these waters were studied in colloidal (CF, extracted by ultrafiltration from the 0.45 μm filtrate) and total dissolved (TDF) fractions and in fractions extracted from corresponding riverbed sediments, according to changes of the B/Li ratio.In river waters, CF and TDF showed very similar B/Li values, suggesting that only negligible fractionation occurs between Li and B in the aqueous phase. Similar evidence was observed between B/Li values in TDF and the labile sediment fraction, whereas an inverse relationship arose between B/Li values in TDF and in the easily reducible sediment fraction. This relationship indicates that Mn oxy-hydroxides preferentially react with aqueous B species relative to Li at the riverbed sediment interface.The extent of the B–Mn oxy-hydroxide reactions is influenced by the ionic strength, so that only B/Li values below 4 are measured in river waters with ionic strength values above 0.5 M. Comparing B/Li and ionic strength values measured in the Platani river with those from oxic brines worldwide, the same preferential B removal relative to Li is observed. This evidence suggests that B is removed as positively-charged borate ion-pairs, formed in the aqueous phase under higher ionic strength conditions, reacting with negatively charged surfaces of Mn oxy-hydroxides. The observed B reactivity relative to Li could be exploited to bring down the B excess from natural or waste waters, allowing the natural reactions with Mn oxy-hydroxides to take place under natural conditions.

Weathering intensity and lithium isotopes: A reactive transport perspective

Lithium isotopes have emerged as a powerful tool to probe the response of global weathering to changes in climate. Due to the preferential incorporation of ^6^Li into clay minerals during chemical weathering, the isotope ratio δ^7^Li may be used to interrogate the balance of primary mineral dissolution and clay precipitation. This balance has been linked to relative rates of chemical and physical denudation, such that dissolved δ^7^Li (δ^7^Li~diss~) is highest at moderate weathering intensities when chemical and physical denudation are comparable. However, we argue that current theory linking δ^7^Li to weathering regimes through fluid travel times are unable to explain observations of low δ^7^Li and high Li concentrations in rapidly eroding settings. In this study, we re-examine the relationships between δ^7^Li, Li concentration, and weathering regime by incorporating Li isotopes into simulations of weathering profiles using a reactive transport model (CrunchFlow) that includes advective fluxes of regolith to simulate variable erosion rates in response to uplift. In these simulations, fractionation is implemented through a kinetic fractionation factor during clay precipitation, which allows the δ^7^Li of dissolved and suspended loads in the model to vary as a function of Li/Al ratios in primary and secondary minerals. When the model is run over a range of infiltration and erosion rates, simulations reproduce observed global patterns of δ^7^Li~diss~ and suspended load δ^7^Li as a function of weathering intensity, controlled primarily by water travel times and mineral residence times in weathered bedrock. We find that reduced water travel times at low weathering intensity, however, are inconsistent with observations of high Li concentrations. As an alternative, we demonstrate how the rapid weathering of soluble, Li-rich minerals such as chlorite under low weathering intensities may resolve this apparent discrepancy between data and theory. We also suggest that observed patterns are consistent with geothermal Li sources under low weathering intensities. This work offers a foundation guiding future studies in testing potential mechanisms underlying global riverine δ*^7^*Li~diss~.

A facile approach for the selective recovery of lithium from spent lithium-ion batteries

The excessive use of lithium-ion batteries (LIBs) poses a potential severe environmental problem. Spent LIBs are prospective lithium (Li) sources. This study aims to recover Li from LIBs and regenerate cathode from the recovered and residual Li. The spent cathode was mixed with a spent anode and heated at a given temperature and time for its reduction. The reduced cathode was leached using carbonated water and was analyzed before and after its leaching. The leachate was examined to determine the Li content, and it was evaporated to obtain solid high purity Li2CO3. At a 6% solid/liquid (S/L) ratio and a 2-L/min CO2 flowrate, the leaching efficiency was 94%, which decreased as the S/L ratio increased. The Li2CO3 purity was close to that of pure Li2CO3 and superior to that of commercial Li2CO3. Regenerated lithium nickel–cobalt–aluminum oxide (RNCA) cathode material was obtained via a reaction of Li2CO3 and the leaching residue. RNCA achieved a discharge capacity of 128 mA h/g at 0.1C (102 mA h/g at 1C) and 79% capacity retention after 50 cycles at 1C. The discharge capacities of a commercial NCA cathode and spent cathode were 133 mA h/g at 0.1C (115 mA h/g at 1C) with 82.6% capacity retention after 50 cycles at 1C and 38 mA h/g at 0.1C with 52% capacity retention after 50 cycles at 0.1C, respectively. The obtained Li2CO3 met the requirements of LIB cathode manufacturing, and the spent NCA cathode could be regenerated to form cathode materials with good characteristics via a simple technique.

Environmental assessment of an innovative lithium production process

The recent development towards a battery-powered electric vehicle industry has led to a significant rise in the demand for high-grade Lithium (Li). Global Li is predominately produced from brines (salar or geothermal) and from hard-rocks, while the amount of Li produced from recycling (e.g. from waste batteries) is still negligible, although it is expected to increase in the near future. Li extraction from hard rocks and brines is also associated with environmental issues, such as (i) consumption of a large quantity of reagents, (ii) high water footprint (especially in the case of brines). Therefore, ensuring a clean, stable and sustainable supply of Li is a key point in the European agenda to reach its ambitious climate targets by 2050.Building on this need, a LiOH production process is under development at KU Leuven (C3 SOLVOLi+ project). This process concentrates technical grade LiCl from the roasting of low-content Li sources. Subsequently, it converts the concentrated technical grade LiCl into aqueous LiOH by mean of a series of processes. The presented environmental analysis, based on a ex-ante Life Cycle Assessment, highlights the potential environmental hotspots that can potentially hinder the breakthrough of the technology, providing useful insights on unit processes requiring optimizations during future upscaling. In particular, at this early stage of development, the optimization and the recycling of the chemicals used in the process seems to be the most efficient strategy to reduce the overall environmental impact of the process. Future studies foresee to enlarge the current analysis to the comparison with other processes for LiOH production. A lower environmental footprint can indeed help to strength the position of the proposed process into the future market for LiOH production.

Stabilizing the nanostructure of Pre-lithiated LiF nanoparticles modified SnO2@graphite nanosheets as a high performance anode material for lithium ions batteries

Graphite nanosheets coated by LiF/SnO2 composites are designed to obtain a lithium ion anode material with excellent performance. LiF nanoparticles play a significant role in improving the electrochemical performance by inhibiting electrolyte decomposition and providing excess Li sources during cycling. The obtained LiF@SnO2@C electrode shows an outstanding capacity of 951.9 mAhg−1 at 0.2 Ag-1 after 370 cycles and excellent long cycling performance of 650.0 mAhg−1 at 1.0 Ag-1 after 930 cycles. First-principles calculations demonstrate that F-doped SnO2 (−2211.8 eV) has a lower free energy compared to SnO2 (−1937.4 eV), resulting in a robust composite architecture that gives rise to high cycling stability.

Pre-Lithiation Strategies for Next-Generation Practical Lithium-Ion Batteries.

Next‐generation Li‐ion batteries (LIBs) with higher energy density adopt some novel anode materials, which generally have the potential to exhibit higher capacity, superior rate performance as well as better cycling durability than conventional graphite anode, while on the other hand always suffer from larger active lithium loss (ALL) in the first several cycles. During the last two decades, various pre‐lithiation strategies are developed to mitigate the initial ALL by presetting the extra Li sources to effectively improve the first Coulombic efficiency and thus achieve higher energy density as well as better cyclability. In this progress report, the origin of the huge initial ALL of the anode and its effect on the performance of full cells are first illustrated in theory. Then, various pre‐lithiation strategies to resolve these issues are summarized, classified, and compared in detail. Moreover, the research progress of pre‐lithiation strategies for the representative electrochemical systems are carefully reviewed. Finally, the current challenges and future perspectives are particularly analyzed and outlooked. This progress report aims to bring up new insights to reassess the significance of pre‐lithiation strategies and offer a guideline for the research directions tailored for different applications based on the proposed pre‐lithiation strategies summaries and comparisons.

Layer spacing gradient (NaLi)1−xCoO2 for electrochemical Li extraction

Layer spacing gradient (NaLi)1−xCoO2 for electrochemical Li extraction

Recent progress of ceramic electrolytes for post Li and Na batteries

Recently, post Li batteries have been intensively researched due to high cost and localization of Li sources, especially for large-scale applications. Concurrently, ceramic electrolytes for post Li batteries also gain much attention to develop all-solid-state post Li batteries. The most intensively researched post Li battery is Na battery because of chemical and electrochemical similarities between Li and Na elements. Many good review papers about Na battery have been published including Na-ion conductive ceramic electrolytes. Contrary, ceramic electrolytes for other post Li batteries like K, Mg, Ca, Zn and Al batteries are hardly summarized. In this review, research on ceramic electrolytes for K, Mg, Ca, Zn and Al batteries is analyzed based on latest papers published since 2019 and suggested future research direction of ceramic electrolytes for post-Li batteries.

Thermo-osmosis-Coupled Thermally Regenerative Electrochemical Cycle for Efficient Lithium Extraction.

Lithium (Li) production based on the soda evaporation process is time-consuming and unsustainable. The emerging electrochemical Li extraction is time-efficient but requires high-concentration Li sources and significant electrical energy input. Here, we demonstrate a fast, energy-saving, and environment-friendly Li production process by coupling a thermally regenerative electrochemical cycle (TREC) using lithium manganese oxide (LMO) and nickel hexacyanoferrate (NiHCF) electrodes with poly(vinylidene fluoride) membrane-based thermo-osmosis (denoted as TO-TREC). The characterization of LMO and NiHCF electrodes confirmed that the relatively high temperature of TO-TREC has negligible adverse effects on the ion intercalation in LMO and NiHCF electrodes. The LMO/NiHCF pair has a positive temperature coefficient of 0.843 mV K-1. In the TO-TREC process, Li ions are selectively extracted from a Li-containing brine warmed by low-grade heat and then released into a room-temperature recovery solution such as LiCl with a production rate of 50-60 mmol Li+ m-2 h-1. Li source solutions are concentrated by thermo-osmosis simultaneously, making it possible to utilize previously unusable Li-containing sources, such as concentrated brines from desalination plants and industrial effluents. Besides, the TREC harvests thermal energy from the heated brine, saving >20% of electrical energy compared to conventional electrochemical methods. The new process shows the potential to meet the growing global Li demands for many applications.

Theoretically Quantifying the Effect of Pre-Lithiation on Energy Density of Li-Ion Batteries

Pre-lithiation plays an increasingly significant role for high-energy Li-ion batteries (LIBs) since it can improve the energy density by compensating the Li loss during the initial cycle. The pre-lithiation related research so far has been focused on the development of materials and methods of pre-lithiation but has lacked theoretical and mathematical descriptions to illustrate the relationship between pre-lithiation and energy density. In this contribution, a series of mathematical formulas are derived to describe the gravimetric and volumetric energy densities of LIBs with pre-lithiation, by which the effects of the important parameters, e.g. the Coulombic efficiencies (CEs) of anode, the capacities of Li sources, etc., on the energy densities are well demonstrated. Then, the developed theory and mathematical formulas are applied to practical LIB systems, i.e. the cell using Li nickel manganese cobalt oxide (NMC) as a cathode and silicon-carbon (Si–C) composite as an anode, to identify possible energy density improvement after pre-lithiation. These systematic formulas with great universality have the potential to give significant guidelines for future studies on the pre-lithiation methods and be useful tools for the design of high energy LIBs with imperfect CEs from fundamental and practical perspectives.

Li-ion conductivity and stability of hot-pressed LiTa2PO8 solid electrolyte for all-solid-state batteries

Solid-state electrolyte as a crucial component in all-solid-state batteries should have high Li-ion conductivity and good stability in air. Recently, a new solid Li-ion conductor LiTa2PO8 (LTPO) with theoretical and experimental Li-ion conductivities of 35.3 and 0.25 mS/cm has been reported. Herein, we systematically investigate the ionic conductivity and chemical stability of the LTPO electrolytes sintered by conventional sintering (CS) and hot-pressing sintering (HP) methods. The effects of Li sources, sintering temperature, and the dwelling time are concerned. LTPO pellets using CH3COOLi·2H2O as the Li source sintered by CS method have a room-temperature Li-ion conductivity of 1.86 × 10–4 S/cm with an activation energy of 0.36 eV. A conductivity of 3.12 × 10–4 S/cm with an activation energy of 0.32 eV is achieved by further HP sintering. Moreover, LTPO shows excellent chemical stabilities in air, aqueous solution, and organic solvent and shows a stable cycling performance in the symmetric Li/Li cells and the all-solid-state Li/LiFePO4 batteries with the separation of a thin PEO membrane.

Hierarchically Nanoporous 3D Assembly Composed of Functionalized Onion-Like Graphitic Carbon Nanospheres for Anode-Minimized Li Metal Batteries.

Despite the recent attention for Li metal anode (LMA) with high theoretical specific capacity of ≈3860 mA h g-1 , it suffers from not enough practical energy densities and safety concerns originating from the excessive metal load, which is essential to compensate for the loss of Li sources resulting from their poor coulombic efficiencies (CEs). Therefore, the development of high-performance LMA is needed to realize anode-minimized Li metal batteries (LMBs). In this study, high-performance LMAs are produced by introducing a hierarchically nanoporous assembly (HNA) composed of functionalized onion-like graphitic carbon building blocks, several nanometers in diameter, as a catalytic scaffold for Li-metal storage. The HNA-based electrodes lead to a high Li ion concentration in the nanoporous structure, showing a high CE of ≈99.1%, high rate capability of 12 mA cm-2 , and a stable cycling behavior of more than 750 cycles. In addition, anode-minimized LMBs are achieved using a HNA that has limited Li content (≈0.13 mg cm-2 ), corresponding to 6.5% of the cathode material (commercial NCM622 (≈2 mg cm-2 )). The LMBs demonstrate a feasible electrochemical performance with high energy and power densities of ≈510 Wh kgelectrode -1 and ≈2760 W kgelectrode -1 , respectively, for more than 100 cycles.

Lithium dilution in Li-Sn alloys

Liquid lithium-tin (Li-Sn) alloys are being considered in alternative concepts of plasma facing components for nuclear fusion applications. Nevertheless, the high Li content and high melting temperature of Li-rich intermetallics may hinder their use due to a possible excessive evaporation of Li to the vessel with evident issues in fuel retention. Their formation was inhibited in this study in homogeneous alloys with Li contents as higher as 5 at.% via a mechanical alloying route of pure Li and Sn sources. A 50 at.% Li-Sn master powder was initially prepared and diluted afterwards with pure Sn to achieve the final compositions. The structure, elemental composition and homogeneity of the alloys were assessed by scanning electron microscopy, ion beam analysis and X-ray diffraction. 5 at.% Li and 1 at.% Li alloys composed by phases with low melting temperatures, LiSn, Li2Sn5 and β-Sn, mainly, were produced with reduced oxygen and metallic impurity contents.

High‐temperature CO2 adsorption over Li4SiO4 sorbents derived from different lithium sources

AbstractLi4SiO4 is a promising sorbent for high temperature CO2 capture. It could be synthesized from three different Li sources (LiNO3, LiOH, and Li2CO3) by using the solid state reaction method. The effects of Li sources on the structure and CO2 adsorption/desorption properties of Li4SiO4 sorbents were analyzed in this work. The results showed that Li4SiO4 sorbents could be synthesized at a lower temperature by using LiNO3 and LiOH as the starting materials, which could reduce the sintering during the synthesis process and increase the surface area of synthesized Li4SiO4. During the CO2 adsorption/desorption cycles, Li4SiO4 sorbents derived from LiNO3 and LiOH presented higher initial CO2 adsorption capacities than those from Li2CO3. After 15 cycles, the adsorption efficiency of Li4SiO4 derived from LiNO3 showed no or slight decrease, while that from LiOH rapidly decreased to 20% of the initial value. This was because Li4SiO4 derived from LiNO3 had high surface area and porosity before CO2 adsorption/desorption cycles, and its surface area even increased after cycles. However, the surface area of Li4SiO4 derived from LiOH decreased greatly due to serious sintering. For Li4SiO4 derived from Li2CO3, its morphology and surface area were almost unchanged before and after CO2 adsorption/desorption cycles.

Simple and Eco-Friendly Fabrication of Electrode Materials and Their Performance in High-Voltage Lithium-Ion Batteries.

The huge consumption of rechargeable Li-ion batteries (LIBs) make it necessary to recover and reuse the different components of spent batteries, thus favoring sustainable development. Graphite is a critical material in the manufacture of the current LIBs so recycling it should be prioritized in the management of spent batteries. In this work, graphite is manually recovered from spent batteries used in smartphones. The impurities from the different components of the batteries are drastically reduced by simple leaching with HCl. This treatment significantly improves the delivered specific capacity, with average values of 300 and 390 mAh g-1 without and with leaching, respectively. To test recycled graphite as an anode material in real cells, it is paired with LiNi0.5 Mn1.5 O4 , the most promising cathode material for high-voltage batteries. LiCl, produced directly by chlorination of spodumene, is used as the Li source to obtain the spinel sample. The real cell gives satisfactory values for both initial specific capacity (100 mAh g-1 ) and capacity retention after 100 cycles. These results are comparable to and in some cases even better than those for cells that use commercial graphite and conventional Li sources as primary raw materials. Moreover, the cell shows good performance during the rate capability test; the delivered capacity values decrease smoothly from 73 to 62 mAh g-1 while the rate increases from 0.1 to 1 C.

High electrochemical stability Al-doped spinel LiMn2O4 cathode material for Li-ion batteries

Abstract High electrochemical stability Al-doped LiMn2O4 (LMO) cathode materials for Li-ion batteries were synthesized using a simple combustion method with degreased cotton fiber as the carrier. The precursors of Mn, Li, and Al sources with different stoichiometric ratios were dissolved into alcohol, then a rapid combustion process was conducted to produce the Al-doped LiMn2-xAlxO4 (x = 0.05, 0.10, and 0.16). The morphology and properties of the Al-doped LMOs were characterized by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Results indicated that both the particle size and lattice parameters of the Al-doped LMOs decreased with an increase in the Al doping ratio, as theoretically supported by the ab initio calculation. This phenomenon is conducive to full contact between the electrolyte and cathode materials, and so can shorten the diffusion distance between of Li+ ions in solid phase. Electrochemical characterization showed that Al doping can improve the cycle performance of LMO. A doping content of 16 at.% to LMO showed excellent electrochemical performance, with a first-charge specific capacity of 100.7mAh/g and a capacity retention rate of 93.9% after 400 cycles at a current rate of 0.5 C.

Biofortification of soybean grains with foliar application of Li sources

Biofortification of soybean grains with lithium (Li) is a strategy to improve a food with high social acceptance, in order to promote health benefits. The aim of this work was to evaluate the development of plants and the production of biofortified soybeans with two Li sources. The experiment was conducted in a completely randomized design with five replicates. Ten treatments were obtained in a 2x5 factorial scheme, comprising two sources of Li (LiOH - Li hydroxide and Li2SO4 - Li sulfate) and five doses (0, 30, 60, 90 and 120 mg kg−1) in stages V4 and R1. The supply of Li promoted significant effects (p ≤ 0.05) on the morphology, yield components and nutritional status of soybean plants. The highest grain yield was obtained with the use of Li2SO4 at the estimated dose of 45.7 mg kg−1. The plants accumulated Li between 8.00 and 11.20 mg kg −1, respectively, with the use of Li2SO4 and LiOH. In the grains, the highest concentrations of Li were obtained with the application of 120 mg kg−1. Li2SO4 and LiOH are good sources for biofortification of soybean grains.