Lithium-rich Brines Research Articles

Boron extraction using selective ion exchange resins enables effective magnesium recovery from lithium rich brines with minimal lithium loss

• Li + loss decreases from 13.7 to 1.4% during Mg(OH) 2 precipitation in the absence of boron. • Chemical-grade Mg(OH) 2 precipitation was possible from brines free of B. • Amberlite IRA743 resin selectivity extract boron from raw Li reach brines. • Resin saturated with boron can be regenerated and reused with the same efficiency. • The high water intake in the presence of B is associated with hydroboracite formation. Magnesium hydroxide is a commodity chemical, produced in almost pure form from seawater through precipitation. Even though Li brines contain high concentrations of Mg 2+ cations, the precipitation of Mg(OH) 2 from them is not common. Rather it is typically coprecipitated with other salts and becomes a waste. The crystallization of chemical-grade Mg(OH) 2 from a Li + rich brine that contained 3.1 g/L Mg 2+ and 1.3 g/L Li + , was investigated by means of NaOH and CaO addition. Direct precipitation of Mg(OH) 2 leads to considerable Li loss and impure crystals due to the brine uptake into the crystal cake. In order to increase the sedimentation rate and decrease the brine loss, a boron extraction step was introduced, which consisted of initial polishing using Amberlite IRA743. It was possible to extract B to below the ICP detection limit from native salt lake brines selectively and regenerate the ion exchangers for repetitive cycles. Upon the extraction of boron, the Mg(OH) 2 sedimentation rate, increased while the loss of Li + from the brine decreased from 13.7 ± 1.2 to 1.5 ± 0.4%. Precipitation with CaO as an alkalizing agent generated a mixture of crystals and a Li + loss between 6.7 ± 0.8 and 3.8 ± 0.7%. When the boron-free brine was alkalized by NaOH, an increase in the degree of crystallinity of Mg(OH) 2 crystal structure was verified by XRD and a purity of 95 ± 2% for the solid was obtained. The high water intake in the presence of B was associated with the presence of hydroboracite in intercalation within the brucite. It was expected that, if the hydroboracite was present as an intercalation, this structure would be disrupted more easily by the ultrasound, potentially resulting in a loss of the hydroboracite d-spacings. Concluding, subsequent B and Mg removal steps from Li + rich brines result in the production of 95% pure Mg(OH) 2 leaving a brine for high purity lithium salt precipitation, thereby bringing a second attractive product from brine processing.

Performance of a double-slope solar still for the concentration of lithium rich brines with concomitant fresh water recovery

Lithium recovery from brines has become a hot topic. The current evaporitic technology is slow, and serious environmental concern has been raised regarding the large volumes of water used, relating both to brine concentration through evaporation, and intensive pumping of fresh water needed in the fine chemical processing to produce high purity lithium carbonate.In this work, an experimental and theoretical analysis of brine desalination using a double-slope Solar Still was carried out. The Solar Still was installed right next to an existing lithium mining facility in northwest Argentina, and was tested with native high salinity lithium rich brine for a continuous year under the typical weather conditions of lithium deposits: high altitude, large thermal amplitude between day and night, strong winds, and high solar radiation. The performance of the solar still as an evaporator was compared with that of a PAN evaporimeter class A, and correlated to experimentally determined weather parameters. While the performance of the Solar Still for brine concentration was below that of open air evaporation, the Solar Still allowed for the production of an average of 2 L day−1 m−2 of distilled water, in marked contrast with current practice. Numerical simulations allowed us to quantify heat exchanges in both the Solar Still and the open air system.

Recovering water from lithium-rich brines by a fractionation process based on membrane distillation-crystallization

In recent years, lithium production has been increasing as a result of the growing market demand. Salt-lake brines are one of the main sources of raw lithium, which can be concentrated and purified by natural evaporation. This time-consuming production causes a loss of around 85–95 % of the water contained in the extracted brine. In this context, new technologies could replace the current process with the aim to improve the water management by recognizing the evaporated water as a critical resource.This study proposes a novel fractionation method, based on a membrane distillation-crystallization process, for concentrating and purifying the lithium brine while recovering fresh water. Synthetic brines containing the major components present in Li-rich brines were assessed at different temperatures, reaching a water flux higher than 3.0 kg/m2h at 50 °C. The process was continuously protracted achieving the fractionation of Na and K salts by controlling the supersaturation of the brine and crystallization. Subsequently, the observed water flux for Mg brine was 0.22 kg/m2h as a result of the water activity decline at high brine concentration (>7.0 mol/kgH2O).Moreover, thermodynamic speciation simulation supported the potentialities of this process, showing the capacity to recover around 95 % of the water contained in real brines from salt-lakes after three stages of separation.Overall, a conceptual flow-sheet of a new membrane-based fractional crystallization method was proposed for: i) the intensification of the brine concentration; ii) the recovery of water (up to 95 %); iii) the brine purification from in presence of major ions (i.e. Li, Na, K and Mg).

Development of a co-precipitation process for the preparation of magnesium hydroxide containing lithium carbonate from Li-enriched brines

Ongoing research to develop a new generation of materials to achieve a more reliable and higher energy density lithium-ion batteries has attracted working groups attention worldwide in academia and industry. Products like lithium carbonate or lithium hydroxide are fundamental as the main feedstock for future materials. Recently, metal-atom substituted cathode materials with various metals has proved to improve the life-time, stability and performance of cathodes and consequently of the batteries. In this regard, this publication describes an approach to remove calcium impurities from industrial Lithium-rich brines with oxalic acid. Moreover, the present magnesium is reduced by the precipitation of magnesium hydroxide in a controlled manner in order to obtain a Lithium-enriched brine with a well-defined magnesium concentration in the absence of calcium. Finally, a process is presented to produce high purity lithium carbonate with controlled concentrations of magnesium between 1% to 3% as magnesium hydroxide. The magnesium hydroxide containing lithium carbonate is produced in a co-precipitation step, where initially the magnesium hydroxide is precipitated and subsequently the lithium carbonate is precipitated in a one-pot process.

Boron extraction from lithium-rich brine using mixed alcohols

Boron removal from lithium-rich brine was systematically investigated by solvent extraction using 2,2,4-trimethyl-1,3-pentanediol (TMPD) dissolved in 2-ethylhexanol and sulfonated kerosene. The extraction parameters were determined, including the concentration of mixed alcohols, lithium and solvents loss. During the extraction, a single TMPD molecule reacted with a single boric acid molecule to form a complex with two C–O–B ester bonds. The mechanism was also verified using density functional theory (DFT). The overall extraction efficiency reached 99.95% by a two-stage countercurrent extraction. NaOH (0.2 mol/L) with an O/A phase ratio of 1:2 was used to strip the loaded organic phase with 99.99% stripping efficiency. The feasible industrial application of this boron extraction method was validated.

Lithium carbonate recovery from brines using membrane electrolysis

The increased demand for lithium salts puts pressure on the available production capacity. The current technology for lithium extraction is highly time consuming and has raised great concern because of the evaporation, on average, of 500 m3 of water per ton of lithium carbonate. We propose a new technology based on membrane electrolysis to crystallize lithium carbonate from lithium-rich brines. Brine that has been previously deprived from divalent cations and reduced in Na+ concentration, is introduced in the middle compartment of a three-compartment electrochemical reactor. This compartment is separated from the anolyte and catholyte by an anion and a cation exchange membrane, respectively. When a current is applied, anions and cations selectively migrate into the anionic and cathodic compartments, respectively. Water reduction increases the pH of the catholyte, which is recirculated in a crystallizer where CO2 is bubbled and converted to carbonate, precipitating Li2CO3 with a purity of at least 93.8 wt %. Current values ranging from 10 to 100 A m−2 were applied, producing cell voltages from 2.5 to 30 V (highest values correspond to end of batch experiments). The method allows to recover as much as 90% of the volume of the lithium containing solution as low salinity water, with up to 99.7% less total dissolved solids than the processed brine, in marked contrast with current practice. In a non-optimized electrochemical reactor, designed for proof-of-concept experiments, the energy consumption for the electrolysis was calculated at 70.6 kWh m−3 of treated brine.

Chemical and isotopic features of Li-rich brines from the Salar de Olaroz, Central Andes of NW Argentina

The lithium-rich brines of the Salar de Olaroz in the Central Andes of NW Argentina are considered to be of great economic and strategic interest. This study focused on the fluid source(s) and geochemical processes governing the chemical and isotopic characteristics of the surficial waters of Olaroz (residual brines, ephemeral lakes, rivers and tributary streams), aiming to define the mechanisms leading to such a huge Li reservoir. The chemistry of the Rosario River, which is one of the main sources of recharge of the Salar de Olaroz, is mostly controlled by fluid inputs from hydrothermal systems located north of the salar (in the volcanic areas of Rosario de Coyaguayma, Pairique, and Cono Panizo). The hydrothermal fluids are characterized by relatively high Li concentrations, as they interact with Li-rich rocks pertaining to Miocene – Pliocene volcanic formations, Ordovician sedimentary deposits, and, possibly, pre-Ordovician crystalline basement. In the salar, the hyperarid climate regulates the relative proportion between supplied waters and evaporation, inducing deposition/dissolution of salts, which controls the concentrations of main ions in brines and ephemeral lakes. Hence, the peculiar combination of a Li-rich primary source, the hydrothermal scavenging by geothermal fluids that feed the Rosario River, and secondary concentration processes affecting the surficial water within the salar leads to the formation of the huge Li reservoir characterizing this area.

Potential water recovery during lithium mining from high salinity brines

Lithium extraction from continental brines involves the evaporation of large amounts of water in open air ponds, in order to concentrate the brine. The evaporitic technology implies the evaporation of large water volumes, raising environmental concerns. If we envision the use of desalination processes for the concentration of lithium-rich brines, then fresh water production/recovery becomes a process well integrated with lithium extraction. Here we apply the Pitzer thermodynamic model with effective molality to estimate activity coefficients for 8 different native brines, and for the resulting concentrated solutions produced by a hypothetical advanced desalinization technique. In all cases, rational activity coefficients deviate considerably from unity. We calculate next the least work of separation for a hypothetical desalination process for the 8 different brines. Because of the large total salinity, the calculation shows that the least work of separation ranges from 18 until 42 kJ kg−1 at nil recovery ratio, and escalating from those numbers as more water is recovered. We can also predict the boiling point elevation, the vapour pressure lowering, and the osmotic pressure. Our calculations show that results are not strictly proportional to the total dissolved solids. Results are strongly dependent with the specific chemical composition of each brine, with the amount of divalent ions (Mg-Ca-SO42−) in particular strongly influencing calculations. Fresh water and lithium minerals production could be part of a single integrated production system.

Hydrochemistry, Distribution and Formation of Lithium-Rich Brines in Salt Lakes on the Qinghai-Tibetan Plateau

Salt lakes on the Qinghai-Tibetan Plateau (QTP) are remarkable for Li-rich brines. Along with the surging demand of Li, the Li-rich brines in salt lakes on the QTP are of great importance for China’s Li supply. Previous studies reported the geological, geographical, geochemical signatures of numerous salt lakes on the QTP; however, conclusive work and the internal relationships among the hydrochemistry, distribution and geological setting of Li-rich salt lakes are still inadequate. In this study, major and trace (Li, B) ionic compositions of 74 Li-rich salt lakes on the QTP were reviewed. The Li-rich brines cover various hydrochemical types (carbonate, sodium sulfate, magnesium sulfate, and chloride types) and present horizontal zoning from the southwest to the northeast along with the stronger aridity. The Li concentrations and Mg/Li ratios in these salt lakes range from 23 to 2895 mg/L, 0.0 to 1549.4, respectively. The distribution of these salt lakes is close to the major suture zones. Geothermal water is proposed to be the dominant source of Li in the investigated salt lakes, while weathering of Li-bearing sediments and igneous rocks, and brine migration provide a minor part of Li. Four factors (sufficient Li sources, arid climate, endorheic basin and time) should be considered for the formation of Li-rich brines in salt lakes on the QTP.

Feasibility and cost minimisation for a lithium extraction problem

In this paper we address the problem of allocating extraction pumps to wells, when exploiting lithium rich brines, as part of the production of lithium salts. The problem of choosing the location of extraction wells is defined using a transportation network structure. Based on the transportation network, the lithium rich brines are pumped out from each well and then mixed into evaporation pools. The quality of the blend will be based on the chemical concentrations of the different brines, originating from different wells. The objective of the problem is then to determine a pumping plan such that the final products have predefined concentrations, and the process is operated in the cheapest possible way. The problem is modelled as a combinatorial optimisation problem and a potential solution to it is sought using a genetic algorithm. The evaluation function of the genetic algorithm needs a method to determine feasible minimum cost flows for the proposed pumping allocation, thus requiring the formulation of a blending model in a flow network for which a new iterative non-convex local optimisation algorithm is proposed. The model was implemented and tested to measure the algorithm’s efficiency.

Membrane electrolysis for the removal of Mg2+ and Ca2+ from lithium rich brines

Lithium is today an essential raw material for renewable energy technologies and electric mobility. Continental brines as present in the Lithium Triangle are the most abundant and the easiest to exploit lithium sources. Lithium is present in diluted concentrations together with different ions, and it is imperative to fully remove both magnesium and calcium before lithium carbonate can be precipitated. Here we use membrane electrolysis as a novel method to generate hydroxyl groups in situ in a two-chamber electrochemical cell with a side crystallizer, omitting the need for chemical addition and not leading to substantial loss of lithium rich brine. Batch electrolysis experiments fully removed more than 99.99% of both Mg2+ and Ca2+ for three different native South-American brines treated at current densities ranging from 27 to 350 A m−2 (final concentrations were below ICP detection limit: < 0.05 mg L−1). For a brine containing 3090 mg L−1 of Mg2+ and 685 mg L−1 of Ca2+, 62 kWh m−3 are needed for the full removal of both cations when a current density of 223 A m−2 is employed. Most importantly, the Li+ concentration in the brine is not affected. The removed cations are precipitated as Mg(OH)2 and Ca(OH)2. Our process has the potential to simultaneously recover lithium, magnesium, and calcium compounds, minimizing waste production.

The effect of brine pumping on the natural hydrodynamics of the Salar de Atacama: The damping capacity of salt flats

The Salar de Atacama is used as a case study to analyse and quantify coupled natural (evaporation and recharge) and anthropogenic processes (pumping of lithium-rich brine) to abstract their patterns to other salt flats using a three-dimensional groundwater flow model. Important changes in the dynamics of the water table between the pre-operational period (1986–1994) and operational period (1994–2015) are observed. The water table exhibited a gradual drawdown during the pre-operational period because the evaporation was greater than the recharge for most of these periods. This negative balance was counteracted by some sharp rises that were produced by direct rainfall events on the salt flat. The deep lateral recharge that arrived from the mountains did not produce abrupt changes in the water table because the rainfall events in the mountains were damped by the distance of the recharge zone and great thickness of the unsaturated zone.The natural evolution of the water table was modified by the intensive brine pumping that was performed in the south-western Salar de Atacama during the operational period. As evaporation depends on the water table depth, the pumping caused a drawdown of the water table, resulting in an evaporation rate reduction that partially compensated for the pumped brine in the water balance of the basin. This effect is defined as the damping capacity of salt flats. Thus, salt flats have a high capacity for dampening oscillations in their water table in response to both natural and anthropogenic disturbances which is of great importance for the management of lake and wetland ecosystems and brine exploitation. The limit of the dampening capacity of salt flats is defined by the evaporation extinction depth, which is in the range of 0.5–2 m.

Lithium recovery by means of electrochemical ion pumping: a comparison between salt capturing and selective exchange

Currently, lithium carbonate is mainly produced through evaporation of lithium-rich brines, which are located in South American countries such as Bolivia, Chile, and Argentina. The most commonly used process, the lime–soda evaporation, requires a long time and several purification steps, which produces a considerable amount of chemical waste. Recently, several alternative electrochemical methods, based on LiFePO4 as a selective lithium capturing electrode and differing for the reaction at the counter electrode, have been proposed. In this work a comparison between the salt capturing method, based on silver / silver chloride reaction, and the selective exchange method, based on ion intercalation reaction in a Prussian Blue derivative, is performed in terms of energy consumption. In particular, the energy consumption is divided in thermodynamic and kinetic contribution, and the theoretical calculations are compared with the experimental results. The experimental results show a good agreement with the theoretical calculation. The selective exchange method shows superior performances to the salt exchange in terms of purity and efficiency, however the energy consumption is higher.

3-Phase Modeling for the Origin of Chinese Lithium-Rich Brines

There are significantly different origins and mineralizations among various lithium-rich brines of the world.As for Clayton Valley,Nevada,the data and interpretations recently presented suggest that the model

Lithium and strontium isotopic systematics in playas in Nevada, USA: constraints on the origin of lithium

Lithium-rich brine in playas is a major raw material for lithium production. Recently, lithium isotopic ratios (δ7Li) have been identified as a tool for investigating water–rock interactions. Thus, to constrain the origin of lithium in playas by the use of its isotopes, we conducted leaching experiments on various lacustrine sediment and evaporite deposit samples collected from playas in Nevada, USA. We determined lithium and strontium isotopic ratios and contents and trace element contents of the leachate, estimated the initial δ7Li values in the water flowing into the playas, and examined the origin of lithium in playas by comparison with δ7Li values of the possible sources. In samples from the playas, δ7Li values show some variation, reflecting differences both in isotopic fractionation during mineral formation and in initial δ7Li value in water flowing into each playa. However, all δ7Li values in this study are much lower than those in river water and groundwater samples from around the world, but they are close to those of volcanic rocks. Considering the temperature dependence of lithium isotopic fractionation between solid and fluid, these results indicate that the lithium concentrated in playas in Nevada was supplied mainly through high-temperature water–rock interaction associated with local hydrothermal activity and not directly by low-temperature weathering of surface materials. This study, which is the first to report lithium isotopic compositions in playas, demonstrates that δ7Li may be a useful tracer for determining the origin of lithium and evaluating its accumulation processes in playas.

Silicate Melt Inclusion Evidence for Extreme Pre-eruptive Enrichment and Post-eruptive Depletion of Lithium in Silicic Volcanic Rocks of the Western United States: Implications for the Origin of Lithium-Rich Brines

To evaluate whether anatectic and/or highly fractionated lithophile element-enriched rhyolite tuffs deposited in arid lacustrine basins lose enough lithium during eruption, lithification, and weathering to generate significant Li brine resources, pre-eruptive melt compositions, preserved in inclusions, and the magnitude of post-eruptive Li depletions, evident in host rhyolites, were documented at six sites in the western United States. Each rhyolite is a member of the bimodal basalt-rhyolite assemblage associated with extensional tectonics that produced the Basin and Range province and Rio Grande rift, an evolving pattern of closed drainage basins, and geothermal energy or mineral resources. Results from the 0.8 Ma Bishop tuff (geothermal) in California, 1.3 to 1.6 Ma Cerro Toledo and Upper Bandelier tephra (geothermal) and 27.9 Ma Taylor Creek rhyolite (Sn) in New Mexico, 21.7 Ma Spor Mountain tuff (Be, U, F) and 24.6 Ma Pine Grove tuff (Mo) in Utah, and 27.6 Ma Hideaway Park tuff (Mo) in Colorado support the following conclusions. Melt inclusions in quartz phenocrysts from rhyolite tuffs associated with hydrothermal deposits of Sn, Mo, and Be are extremely enriched in Li (1,000s of ppm); those from Spor Mountain have the highest Li abundance yet recorded (max 5,200 ppm, median 3,750 ppm). Forty-five to 98% of the Li present in pre-eruptive magma was lost to the environment from these rhyolite tuffs. The amount of Li lost from the small volumes (1–10 km3) of Li-enriched rhyolite deposited in closed basins is sufficient to produce world-class Li brine resources. After each eruption, meteoric water leaches Li from tuff, which drains into playas, where it is concentrated by evaporation. The localized occurrence of Li-enriched rhyolites may explain why brines in arid lacustrine basins seldom have economic concentrations of Li. Considering that hydrothermal deposits of Sn, Mo, Be, U, and F may indicate potential for Li brines in nearby basins, we surmise that the world’s largest Li brine resource in the Salar de Uyuni (10 Mt) received Li from nearby rhyolite tuffs in the Bolivian tin belt.

The role of climate in the accumulation of lithium-rich brine in the Central Andes

Lithium-rich brine within the sub-surface of the Salar del Hombre Muerto (SHM) salt pan in the Andes of northwestern Argentina has a chemical and isotopic composition which is consistent with Li derived from several sources: the modern halite saturated lagoon, Li-rich salts and brines formed recently, and dissolution of halite which precipitated from ancient saline lakes. SHM lies in the closed basin that includes part of the massive Cerro Galán caldera which is drained by the Río los Patos, which is responsible for 90% of surface runoff into the salar. The low Li isotope composition, +3.4‰, of this river is consistent with significant contributions of geothermal spring water. As water drains through the volcaniclastic deposits which cover a large proportion of the basin, Li removal, as indicated by decreasing Li/Na, occurs but without significant isotope fractionation. This indicates a mechanism of surface sorption onto smectite or ferrihydrite rather than Li incorporation into octahedral structural sites of clays. These observations suggest that conditions in this high altitude desert have limited the dilution of hydrothermal spring water as well as the formation of clay minerals, which jointly have allowed the Li resource to accumulate rapidly. Changes in climate on a multi-millennial time scale, specifically in the hydrologic budget, have resulted in solute accumulation rates that have been variable through time, and decoupled Li and Na fluxes. Inflow to the salar under modern conditions has high Li/Na (7.9×10−3 by wt) with δ7Li indistinguishable from basement rocks (−0.3‰ to +6.4‰), while under pluvial climate conditions the Li/Na of the saline lake was 40 times lower than the modern lagoon (0.1–0.3×10−3 compared to 10.6–13.4×10−3) with slightly higher δ7Li, +6.9‰ to +12.3‰, reflecting the uptake of 6Li into secondary minerals which formed under a wetter climate.

Toxicity of lithium to humans and the environment—A literature review

Lithium concentrations in the surface and underground waters may be higher than general environment in places where lithium-rich brines and minerals occur, and in places where lithium batteries are disposed of. This review has indicated that lithium is not expected to bioaccumulate and its human and environmental toxicity are low. Lithium is not a dietary mineral for plants but it does stimulate plant growth. Large doses of lithium (up to 10 mg/L in serum) are given to patients with bipolar disorder. At 10 mg/L of blood, a person is mildly lithium poisoned. At 15 mg/L they experience confusion and speech impairment, and at 20 mg/L Li there is a risk of death. A provisional recommended daily intake of 14.3 μg/kg body weight lithium for an adult has been suggested.

Chemical composition and distribution of lithium-rich brines in salar de Uyuni and nearby salars in southwestern Bolivia

Preliminary investigations at Salar de Uyuni and the nearby salars (salt pans) of Coipasa and Empexa in the southern part of the Bolivian Altiplano show the presence of widespread lithium-rich brines. Widely scattered brine samples from Salar de Uyuni, which has an area of about 9000 km2 and is the largest salt pan on earth, show lithium values ranging from 80 to 1500 ppm. High values of 300–700 ppm are most prevalent in an area of about 2500 km2 in the east-central and southeastern part of the salar. A few brine samples in small areas in Coipasa and Empexa Salars have values ranging from 170 to 580 ppm Li. All the brines are essentially saturated with halite and are moderately high in sulfate (5000–15,000 ppm SO4) but low in carbonate (<500 ppm HCO3). Potassium and magnesium values are relatively high, chiefly in the range of 2000–20,000 ppm, and the KMg ratio is about 1:1. The LiK and LiMg ratios are relatively constant at about 1:20.The crystalline saline material and brines in these salars are residual from a former large lake, Lago Minchin, that occupied much of the southern Bolivian Altiplano during late Pleistocene time, augmented by saline material carried to the salars by streams since final drying of this lake. Thermal springs associated with rhyolitic volcanic rocks of Quaternary age may have been a major source of the lithium.

Welding by friction. (in Polish) : Jerzy Orlowski. Przeglad techniczny, v. 78, no. 17, Sept. 1957, p. 668–669

Full depletion of magnesium cations from lithium rich brines is vital for the successful crystallization of battery grade lithium salts in subsequent production steps. In a three compartment water electrolyser, we demonstrate the full abatement of Mg2+, with concomitant recovery of magnesium hydroxide. We have studied the influence of three operational variables, current density, temperature and forced mass transport in the coulombic efficiency, cell voltage between the electrodes, solid purity and lithium ions loss. Response surface methodology was used to model the system. Our results show that both in terms of energy efficiency, product purity and minimal Li+ loss it is best to work at very low current density, high flow rate, and high temperature (32 A m−2, 60 °C, and 18 L h−1). Working at higher current density, low temperature, and high flow rate (100 A m−2, 26.5 °C, and 18 L h−1) still guarantees a product of acceptable quality while keeping a moderate electrical consumption. The current density is the factor that affects results the most. High current densities are correlated with a faster nucleation, and smaller particle size, resulting in higher adsorption from other ions and co-precipitation of CaB by-products.