13. Life Cycle Assessment of Emerging Battery Systems

An emerging development in lithium-based battery chemistries is the use of solid-state electrolytes instead of the typical liquid- or gel-based electrolytes used in incumbent lithium-ion batteries.

A recent LCA of a solid-state lithium-ion battery performed by Zhang et al. [45] focused on characterizing the environmental impacts of producing a small-scale coin cell with a solid-state lithium-aluminum-titanium-phosphate (LATP) chemistry and comparing its impacts to a cell with a conventional liquid-based electrolyte for lithium-ion batteries. That study demonstrated that production of one solid-state LATP cell in the CR2032 form factor required higher primary energy inputs than a conventional lithium-ion cell of the same form factor (2.6 MJ vs. 1.1 MJ) and produced roughly double the greenhouse gas emissions (0.1 kg CO₂e vs. 0.05 kg CO₂e). This was primarily driven by the energy intensity of producing the inorganic solid electrolyte. Efforts to reduce the required thickness of the electrolyte layer were found to reduce all the environmental impact indicators considered in the study significantly, highlighting the need for manufacturing improvements for this technology. A previous LCA for a solid-state lithium battery performed by Troy et al. [32] focused on the production of a pouch cell based on a lithium-lanthanum-zirconium-oxide (LLZO) chemistry. Troy et al. did not compare the environmental impact results with incumbent battery technologies due to the relative immaturity of the solid-state cell with commercial technologies at the time, but their results show that on-site electricity use for cell production is the largest contributor to impacts. Depending on where manufacturing occurs, the environmental impacts from electricity use can vary dramatically.

Focusing on the pack level, Keshavarzmohammadian et al. [18] conducted an LCA for a solid-state lithium-ion battery pack with a pyrite cathode (iron sulfide) for application in electric vehicles. The study scope more closely mimics the production processes that would be used to produce real-world battery systems. The study found that cumulative energy demand and contributions to greenhouse gas emissions from the pyrite-based solid-state pack are on the same order of magnitude as that of conventional lithium-ion batteries. The largest contribution toward these impacts was again the energy use for cell production, more specifically the operation of clean dry rooms and the production of cathode paste.

In perhaps the earliest LCA study of solid-state batteries, Lastoskie and Dai [19] performed a comparative LCA to assess the environmental impacts of producing a solid-state cell relative to that of a laminated cell with a gel electrolyte for electric vehicle applications. They examined various cell chemistries for each type and scaled the results into battery packs and vehicle assemblies. The study demonstrated that, compared to laminated cell chemistries, solid-state batteries had lower environmental impacts across multiple indicators, depending on the chemistry chosen. Specifically, solid-state lithium vanadium oxide electrolytes exhibited the lowest environmental impacts across all the environmental impact indicators considered. The solid-state batteries specifically provided benefits during the use phase of the electric vehicles due to higher energy density that reduced energy consumption during vehicle operation. Cell chemistry variations had a significant effect on production phase impacts.

Overall, present literature on LCAs of solid-state battery technology shows that there is still much uncertainty regarding the existence or extent of environmental benefits from using solid-state batteries compared to conventional lithium-ion batteries. The environmental impacts of these systems are generally found to be similar to that of conventional lithium-ion batteries but, depending on the scope of the assessment and the specific chemistries used, can be higher or lower than conventional batteries. In designing future solid-state battery systems, care must be taken to identify and avoid unintended consequences that contribute to high environmental impacts.

Another emerging development for batteries based on lithium is the use of lithium metal anodes instead of traditional graphite-based anodes. Lithium metal anodes potentially provide the benefit of increased energy and power densities compared to batteries with conventional anodes but are presently subject to multiple material stability issues during use [37]. Nonetheless, prospective LCAs of battery systems or components containing lithium metal anodes have been conducted. Berg and Zackrisson [8] conducted a cradle-to-grave LCA of metal anodes for lithium battery packs used in electric vehicles using computer simulations of the battery cells as opposed to physical fabrication, focusing on greenhouse gas emissions from a life cycle perspective. They showed that lithium iron phosphate (LFP) and nickel manganese cobalt (NMC) batteries based on lithium metal anodes exhibit lower life cycle greenhouse gas emissions compared to their conventional counterparts used in Nissan Leaf and Tesla Model S vehicles. Emissions reductions for the Nissan Leaf ranged from 50% to 58% of the original pack, while that for the Tesla Model S ranged from 20% to 39% of that of the original pack. This study shows the potential environmental benefits of batteries with lithium metal anodes, but these results require validation by assessment of physically produced cells.

Vandepaer et al. [34] performed a cradle-to-grave LCA of LFP batteries comparing the use of lithium metal anodes (lithium metal polymer or LMP) versus traditional graphite anodes in a stationary grid-connected application, differentiating between systems deployed at the distributed vs. centralized scale. This study showed that LMP batteries exhibited lower contributions to detrimental human health impacts (~18% reduction) and climate change (~23% reduction) but similar contributions to ecosystem damage and resource use compared to conventional graphite anode batteries, for both the centralized and distributed systems. These results are strongly driven by the assumptions for the sourcing and production of battery materials – aluminum from China produced using coal power in the graphite anodes versus aluminum sourced from Canada using hydropower in the metal anodes. Therefore, the study highlights the key factor of emissions generated from metal production and their sensitivity to the energy source used for production.

Wu and Kong [40] also performed a comparative cradle-to-gate LCA of lithium-ion battery production with three different anode materials: lithium metal, silicon nanowire, and traditional graphite anodes, all used in batteries with a common chemistry (NCM). When focusing on the production of a given mass of anode material alone, this study found that the conventional anode material exhibited the lowest contributions toward six of eight midpoint environmental indicators examined, with lithium metal anodes exhibiting the lowest contributions toward metal depletion potential and marine eutrophication potential. The silicon nanowire anode exhibited the highest impacts across all categories. In translating these results to the production of full battery systems of the same energy capacity (1 kWh), however, the batteries made with lithium metal anodes exhibited the lowest contributions toward all eight environmental impact indicators considered in the study, with the most significant benefits occurring for marine eutrophication potential. This results from differences in the specific energy of the different anodes: anodes with higher specific energy will require a lower mass of anode to be produced to enable a battery with a given energy capacity. Lithium metal anodes have specific capacities of roughly ten times that of conventional graphite anodes but do not have ten times the environmental impacts; therefore, full battery systems produced with lithium metal anodes exhibited the lowest environmental impacts. The study demonstrated, however, that these benefits occur when the cycle life of the lithium metal-based battery is similar to that of batteries with conventional anodes; lower cycle life will reduce or eliminate the cradle-to-gate environmental benefits of lithium metal batteries.

Padashbarmchi et al. [23] performed a comparative, cradle-to-grave LCA of the lithium-ion batteries produced using three different metal oxide nanoparticles as the anode active material, iron oxide, cobalt oxide, and copper oxide, and compared these against a battery with a traditional graphite anode. The study presented environmental impacts using an aggregated metric of Eco-indicator points from the Eco-indicator99 framework. Based on this metric, batteries produced with two of the metal oxide-based anode materials (iron oxide and cobalt oxide) exhibited lower environmental impact scores than batteries with traditional graphite anodes, with batteries based on copper oxide obtaining higher environmental impact scores. For individual endpoint indicators, all three metal oxide anodes showed lower resource depletion impacts than the traditional graphite anode, while copper oxide exhibited a very high contribution to human health impacts that drove its total indicator score. This study shows that metal anodes have the potential to have a lower impact than conventional anode materials depending on the materials chosen.

The present literature on LCAs of metal anode technology for lithium-ion batteries shows that wider use of this technology have the potential to reduce environmental impacts compared to conventional anode batteries in both mobile and stationary applications.

Concerns regarding the criticality and geopolitics of access to lithium resources have also driven interest in developing and scaling battery chemistries that depend on elements other than lithium for their active anode element. Specifically, other alkali metals (sodium, potassium), alkaline earth metals (magnesium, calcium), and metals such as aluminum are of interest for lithium alternatives, described in Part V, as well as organic materials.

Peters et al. [24] performed the first-of-its-kind LCA of the production (cradle-to-gate) of a sodium-ion battery pack and compared its impacts using six midpoint environmental indicators with those for different lithium-ion battery packs. They also explored the sensitivity of these impacts to cycle life, round-trip efficiency, and material substitution of anode hard carbon precursors. They found that with a cycle life of 2000 cycles, sodium-ion environmental impacts were lower than lithium-ion batteries on two indicators (freshwater eutrophication and human toxicity), within the range of lithium-ion batteries for three indicators (global warming, fossil depletion, and terrestrial acidification), and higher impacts than lithium-ion batteries for marine eutrophication potential. Battery cycle life was found to be a major factor in comparing sodium-ion battery environmental impacts versus lithium-ion batteries: a drop to a cycle life of 1000 caused sodium-ion batteries to generally perform worse than lithium-ion across indicators, while increases to 3000 or higher led to lower impacts than most lithium-ion battery types. This study also highlights the potential for improvement in these impacts from material selection for the anode and cathode as well as its precursors and production method.

Jasper et al. [16] included a sodium-ion battery in a comparative, cradle-to-grave life cycle assessment of a home battery system operated to increase the use of otherwise curtailed solar electricity generation, where it was compared against three lithium-ion chemistries based on a functional unit of 1 kWh of electricity delivered. A sodium nickel magnesium manganese titanium oxide cathode and a hard carbon anode were selected to represent the sodium-ion battery. For the full life cycle of these systems, sodium-ion batteries were found to have higher contributions to global warming potential, resource depletion, and freshwater toxicity than the three lithium-ion battery systems. These results were driven by the relatively lower energy density of the sodium-ion battery compared to the lithium-ion batteries at the time of publishing, which requires a larger material mass to be produced to deliver 1 kWh of electricity. Since this larger material mass increases the scale of all life cycle processes, their emissions also increased. It is important to note that between the time of the study [16] and that of the initial study by Peters et al. [24], the energy density of lithium-ion battery technology has improved, which explains the difference between the results of these studies. Another recent study by Carvalho et al. [10] that conducted a comparative cradle-to-gate LCA of lithium-ion and sodium-ion batteries also found that producing a sodium-ion battery contributed more to climate change and resource use than lithium-ion batteries on a per-unit energy capacity basis, also due to its lower energy density.

For mobile applications, Marmiroli et al. [20] performed a cradle-to-grave LCA of a sodium-nickel-chloride battery used in commercial light-duty vehicles, which was then compared on a consistent basis with the results of an LCA of an NMC lithium-ion battery and that for a diesel vehicle used in the same application by Accardo et al. [1]. These studies found that per kWh of battery capacity across their entire life cycle, the sodium battery contributed the most toward 7 of the 12 midpoint indicators with their assumed production location, increasing to 8 of 12 indicators when the batteries are assumed to be produced in Europe. Generally, the impacts from the sodium battery were higher than that of the NMC lithium-ion battery.

Present literature on sodium and sodium-ion batteries initially showed promise for this technology to offer a lower environmental impact option for meeting the battery capacity needs of the transition to a clean energy system. Improvements in the energy density of lithium-ion batteries, however, have reduced this prospect with many studies showing higher life cycle environmental impacts for sodium-ion batteries. Depending on the criticality of lithium as battery demand grows over time, sodium-ion batteries may still offer an important alternative in some applications.

Beyond sodium-based batteries, LCAs of closed system batteries based on other alternatives to lithium are relatively sparse. Potassium and calcium batteries have been discussed from materials performance standpoints [2, 5, 12, 25, 26] but have not yet been the subject of a formal life cycle assessment. Aluminum and magnesium batteries have been the subject of some initial assessments.

Delgado et al. [28] performed a comparative, cradle-to-grave LCA of an aluminum-ion and a lithium-ion battery (NMC chemistry) cell, focusing on their contributions to global warming potential on per-cell and per-energy capacity bases. This study found that on a per-cell basis, the aluminum-ion battery contributed 30% lower greenhouse gas emissions than lithium-ion but on a per-energy capacity basis contributed as much as 12 times the greenhouse gas emissions of the lithium-ion battery. These results were driven by the significantly lower energy density of the aluminum-ion battery, resulting in much more material mass required to achieve a given energy capacity.

Melzack et al. [21] conducted a cradle-to-gate LCA of an aqueous aluminum-ion battery and compared these results to those of supercapacitors on a per-power capacity basis. This application better suits the aluminum-ion battery which has high specific power but low energy density. This study found that the aluminum-ion battery exhibited lower or similar impacts than graphene and activated carbon-based supercapacitors on multiple environmental impact indicators, including but not limited to global warming potential, terrestrial eutrophication, and ozone formation. The relatively early development stage of the aluminum-ion battery implies the potential for improvements to its environmental performance. In applications requiring high specific power, it is more competitive with incumbent technologies.

Montenegro et al. [22] conducted a cradle-to-gate LCA of a magnesium-sulfur (MgS) battery cell with three different cell construction designs and compared it to those for lithium-ion batteries (LFP, NMC, and lithium-sulfur or LiS). The cell construction design for the MgS battery was found to be a major driving factor in its environmental impact profile, with designs that optimize the cell separator thickness and pouch housing reducing contributions to global warming potential and fossil fuel depletion to be similar to or lower than that of the lithium-ion batteries. The optimized cell design for the MgS battery did exhibit higher material depletion and ozone depletion potential than the initial design, but these impacts fell within the range of values spanned by lithium-ion batteries. This study highlights the importance of fundamental cell design in driving larger-scale environmental impacts and competitiveness of the MgS battery. This work was expanded in a study by Bautista et al. [7], which takes the optimized cell design from Montenegro et al. [22] and expands the scope of the LCA to a full modeled battery pack, including the use phase of different battery applications on the electric grid, and compares the results against three lithium-ion battery chemistries. This study found that the modeled MgS battery still contributed environmental impacts that were similar to or lower than the range spanned by lithium-ion batteries across all of the environmental impact indicators included and across the different grid applications. The environmental impacts of the MgS battery were found to be most sensitive to the assumption for the round-trip efficiency of the system in all applications.

The literature on magnesium-based batteries shows promise for this technology in competing against lithium-ion batteries from an environmental impact standpoint, but this potential needs to be verified by LCAs based on physically produced packs and tracked as production methods for this technology scales up to maturity.

Organic alternatives for battery materials are also of interest due to their potential benefits for reduced environmental impact and resource depletion potential. A study by Zhang et al. [46] performed a cradle-to-gate LCA of a fully organic closed system battery based on organic polymers. This study did not perform a direct comparison to other battery technologies but rather focused on identifying hotspots and major contributors to environmental impacts to inform future needs for changes in production processes and material selection. This study found that the dominant contributor to environmental impacts was the production of the organic cathode backbone due to the large number of steps involved requiring significant quantities of solvents. For future improvements, optimizing the cathode backbone production processes to reduce or eliminate the need for solvents will be important for reducing the environmental impacts of this battery at scale.

Many flow battery chemistries exist at different stages of technological and commercial maturity; therefore, relatively few of them have been the subject of LCA studies. The earliest flow battery to reach commercial scale and presently the most mature is the vanadium redox flow battery (VRFB), which has been the subject of multiple LCAs. The first LCA including a vanadium redox flow battery was conducted by Rydh [27] in 1999, which compared the life cycle environmental impact of the VRFB with a lead-acid battery and found that the VRFB exhibited lower environmental impact (using an aggregated environmental impact score) than lead-acid batteries.

A more recent LCA was conducted by Weber et al. [38], which conducted a cradle-to-cradle LCA of a VRFB based on a more detailed, up-to-date dataset of this technology compared to the original inventory from Rydh [27] that was used in multiple studies and compared the results to a lithium titanate-based LFP battery. This study demonstrated that for the VRFB, components related to the electrolyte were the strongest drivers of multiple environmental impacts including contributions to global warming potential, due to the large weight fraction of the electrolyte and related components and the environmental impact of vanadium production. When compared to the lithium-ion battery, the VRFB exhibited lower or similar environmental impacts for three of the four environmental impact indicators (global warming, human toxicity, abiotic depletion) when electricity inputs to battery life cycle processes were assumed to come from clean sources such as wind and solar. When electricity inputs are fossil-based, VRFB impacts are higher than lithium-ion due to its lower round-trip efficiency, requiring more fossil-based generation (and subsequent environmental impacts) for each unit of electricity delivered by the battery.

Additional LCA studies have also focused on or included the VRFB. A study by AlShafi and Bicer [4] conducted a comparative LCA between the VRFB, compressed air energy storage, and molten salt thermal storage based on per kWh of electricity delivered from solar energy. Of these systems, the VRFB was found to contribute the most toward all five of the environmental impact indicators considered, driven by the dominance of copper in the system and the environmental impacts of solar PV. A study by da Silva Lima et al. [30] conducted a comparative, cradle-to-grave LCA of a VRFB and an NMC-based lithium-ion battery on a per kWh of renewable electricity delivered basis. Across their whole life cycle, the environmental impacts of the VRFB were found to be similar or lower than that of the lithium-ion battery when both were constructed with virgin materials but generally lower than that of lithium-ion batteries when 50% of the VRFB electrolyte is recycled. This study also highlights the prominence of the VRFB electrolyte in driving environmental impacts due to its large mass fraction in the overall system and energy-intensive production processes.

Recent LCAs have also started to assess new flow battery chemistries that have only recently reached commercial scale. A study by He et al. [13] conducted a comparative cradle-to-gate LCA of three flow battery chemistries: the VRFB, the zinc-bromide flow battery (ZBFB), and the iron flow battery (IFB), based on up-to-date manufacturer data for commercial systems. This was the first study to conduct LCAs of the ZBFB and IFB systems, despite these systems already being deployed at a small commercial scale. This study found that of these three systems, the IFB generally exhibited the lowest environmental impacts in six of eight midpoint impact indicators due to its use of relatively benign materials, the exception being freshwater ecotoxicity and ozone depletion potential due to materials used in the cell membranes. The ZBFB generally exhibited the second largest contribution to environmental impacts but contributed the most to abiotic resource depletion. The VRFB exhibited the highest environmental impacts on seven of the eight impact indicators included in the study, strongly driven in five of those impact categories by the production of the VRFB electrolyte based on vanadium pentoxide. The VRFB results, however, were shown to be highly sensitive to the assumed production process of the vanadium pentoxide electrolyte, with lower emissions processes potentially reducing environmental impacts in four of the eight categories to be competitive with the IFB. This study highlights the importance of not only material selection but also reducing the emissions intensity of production processes for key materials that are required for flow battery operation. The results of this study were used in a further study by Tian et al. [31] that assessed how the emissions saved from the deployment of the three different flow batteries on a renewable electric grid scale versus the emissions contributed from producing these batteries as the installed capacity of these batteries on the grid increases. Extending the themes from the study by He et al. [13], the IFB enabled the largest capacity of batteries to be installed while ensuring that the emissions benefit outweighed battery production emissions due to the low greenhouse gas emissions intensity of IFB production. Conversely, the VRFB had a much lower ceiling on how much capacity can be installed before battery production emissions overtook the emissions saved on the grid. Selecting lower emissions intensity production methods for vanadium pentoxide increased this capacity ceiling, however.

Flow battery systems with organic electrolytes are also an emerging technology with the possibility to reduce the potential environmental impacts and resource depletion effects associated with inorganic electrolytes [9, 39]. Organic flow batteries are relatively new and as of this writing (mid-2022) are just starting to be commercialized. Therefore, LCAs of this class of technologies are relatively sparse in the research literature, but one very recent (published 2022) study focused on performing LCAs of flow batteries with organic electrolytes.

A study by Di Florio et al. [11] performed a comparative, cradle-to-gate LCA of a semi-organic flow battery using anthraquinone disulfonic acid and hydrobromic acid as electrolyte materials and compared the impact results against a VRFB on a per 1 MWh of electricity delivered basis for renewable energy shifting. This study found that the semi-organic flow battery exhibited lower environmental impacts on 8 of the 11 categories of environmental impacts considered. The three exceptions were stratospheric ozone depletion, mineral resource scarcity, and cumulative energy demand; however, the semi-organic flow battery and the VRFB exhibited similar contributions in these cases, and their differences were found to be within the band of uncertainty for the analysis. These results were largely driven by the lower contributions to environmental impacts from electrolyte production, highlighting the benefit of the semi-organic electrolyte. However, the semi-organic electrolyte was assessed for two different production pathways, air oxidation and dichromate oxidation, and the beneficial results apply to the air oxidation pathway, with the dichromate oxidation pathway exhibiting higher environmental impacts for the electrolyte production.

Metal-air batteries are an emerging technology of interest due to their advantages over conventional lithium-ion batteries in energy density. By using ambient air as the external cathode for the system, these systems can weigh significantly less than closed system batteries. From an LCA standpoint, lithium-air batteries have been the primary focus of study due to their energy density.

Iturrondobeitia et al. [15] performed a cradle-to-gate LCA of seven different chemistries of lithium-oxygen batteries. The study results were compared against lithium-ion, lithium-sulfur, and sodium-ion batteries when used in electric vehicles on a per-unit energy capacity basis. This study found that compared to the lowest emission closed system battery (lithium-ion), five of the seven lithium-air chemistries produced lower greenhouse gas emissions. The two exceptions were the cobalt carbonate-based and gold/nickel-based lithium-air batteries, which produced 208% and 175% of the greenhouse gas emissions produced by the lithium-ion battery, respectively, largely driven by emissions from the production of the battery cathode. For the average of the seven lithium-air chemistries across all the 18 environmental impact indicators considered, lithium-air batteries exhibited improved environmental impacts compared to any of the closed system batteries in 10 out of 18 environmental impact indicators. Notably, lithium-air batteries required significantly larger land use than the closed system batteries, 17 times more than the lithium-sulfur and 7.6 times more than the lithium-ion battery, but the study did not explicitly elaborate on the driver of this result. Certain lithium-ion chemistries, such as the battery based on porous carbon, exhibited lower environmental impacts than the lowest impact closed system battery on 16 of the 18 environmental impact indicators. This study highlights how, depending on the chemistry, lithium-air batteries may or may not provide environmental benefits over closed system batteries even with their higher energy density.

Uludag and Yay [33] conducted an LCA of a lithium-air battery based on a tetraethylene glycol dimethyl ether and lithium hexaphosphate electrolyte, produced with and without electrolyte stabilizers. The study results were compared with closed system batteries for contributions to greenhouse gas emissions. This study found that the lithium-air batteries on average exhibited similar greenhouse gas emissions when produced without stabilizers or when produced with aluminum oxide stabilizers, but markedly lower greenhouse gas emissions when produced with silicon dioxide stabilizers. The configuration with silicon dioxide stabilizers enabled a higher energy density, almost twice that of the configuration when produced with aluminum oxide stabilizers and 43% more than the configuration without stabilizers. This caused the silicon dioxide configuration to exhibit the lowest environmental impacts across all four of the environmental impact indicators considered. When compared to closed system lithium-ion batteries, the silicon dioxide configuration exhibited only 61% of the greenhouse gas emissions of the lowest emission lithium-ion battery (lithium manganese oxide in this study). This study further highlights the importance of optimizing battery production pathways to realize the environmental benefits of lithium-air batteries over incumbent technologies.

Wang et al. [36] performed a comparative, cradle-to-grave LCA of a lithium-oxygen battery and a closed system NMC lithium-ion battery when used in electric vehicle applications. Production of the negative electrode was found to be a major or driving contributor to 11 of the 13 environmental impact indicators in the production phase of the system, with the exceptions being global warming potential and fossil depletion potential, where cell assembly is the major contributor. The impacts from the negative electrode are driven by the impacts associated with the production and use of copper, whereas impacts from cell assembly are driven by the production and use of carbon nanotubes. From the cradle-to-grave perspective, the lithium-oxygen battery exhibits lower environmental impacts in 9 of the 13 environmental impact indicators, with the exceptions being terrestrial ecotoxicity, ozone depletion, human toxicity, and fossil depletion.

Zackrisson et al. [44] conducted the initial LCA of lithium-air batteries, applying a cradle-to-grave approach to assessing a prototype lithium-air battery intended for use in an electric vehicle. At the time of this study [44], environmental impacts contributed by the lithium-air battery were dominated by the production phase of the system. Impacts from the use of copper dominated impacts on ecotoxicity, human toxicity (cancer and non-cancer), and abiotic depletion, while emissions from electricity use dominated contributions to global warming potential. This initial study projected that as lithium-air battery technology develops, the use phase will come to represent the majority of environmental impacts.

Metal-air batteries based on metals other than lithium have not been investigated extensively with LCA tools. Yang and Knickle [42] conducted a preliminary analysis of an aluminum-air battery in 2002, well before the large-scale commercialization of electric vehicles, and focused on life cycle cost instead of environmental impacts. From an environmental standpoint, Santos et al. [29] performed a cradle-to-gate LCA of a zinc-air battery based on the laboratory-scale fabrication of the cell. A comparison of the zinc-air environmental impacts to incumbent technologies was not provided due to the use of a laboratory-scale production process; this study highlighted major contributors to the environmental impacts of this technology. This study found that cathode production was the largest contributor to 12 out of 14 environmental impact indicators, the two exceptions being non-cancer human toxicity and mineral/fossil/renewable resource depletion – where the zinc anode was the largest or dominant contributor. From a cost standpoint, this study also found that the zinc-air battery exhibited the lowest costs compared to incumbent battery technologies on a per-power capacity basis (kW) but one of the higher costs on a per-energy capacity basis.

Lithium-air technologies potentially offer promising environmental impact reduction benefits compared to incumbent battery technologies, but the careful configuration of material selection and production pathways is required to realize these benefits. Due to the relatively immature state of metal-air technologies, repeating LCAs for these batteries if they achieve scale will be required. Knowledge of the environmental impacts of metal-air batteries using metals other than lithium is presently too sparse in the literature to estimate their potential for providing reduced environmental impacts. Additionally, in real-world operation, certain metal-air batteries are sensitive to air purity; substances such as water vapor in the air, for example, can degrade and damage such systems [3].