Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Performance and cost of materials for lithium-based rechargeable automotive batteries


It is widely accepted that for electric vehicles to be accepted by consumers and to achieve wide market penetration, ranges of at least 500 km at an affordable cost are required. Therefore, significant improvements to lithium-ion batteries (LIBs) in terms of energy density and cost along the battery value chain are required, while other key performance indicators, such as lifetime, safety, fast-charging ability and low-temperature performance, need to be enhanced or at least sustained. Here, we review advances and challenges in LIB materials for automotive applications, in particular with respect to cost and performance parameters. The production processes of anode and cathode materials are discussed, focusing on material abundance and cost. Advantages and challenges of different types of electrolyte for automotive batteries are examined. Finally, energy densities and costs of promising battery chemistries are critically evaluated along with an assessment of the potential to fulfil the ambitious targets of electric vehicle propulsion.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Battery value chain and lithium ion versus Li-metal cell chemistries.
Fig. 2: Production processes for negative electrode materials for LIB and Li-metal cells.
Fig. 3: Energy densities and energy efficiencies of electrode materials at the material level.
Fig. 4: Production processes for positive electrode materials for LIB cells.
Fig. 5: Production processes for separators and electrolytes.
Fig. 6: Energy density versus specific energy diagram of different cell chemistries at electrode stack level.
Fig. 7: Cost estimations for different cell chemistries at electrode stack level.


  1. 1.

    Westbrook, M. H. The Electric Car: Development & Future of Battery, Hybrid & Fuel-Cell Cars (Institution of Engineering and Technology, 2001).

  2. 2.

    Reddy, T. Linden’s Handbook of Batteries, 4th Edition (McGraw-Hill Education, New York, 2010).

  3. 3.

    Winter, M. & Besenhard, J. O. Wiederaufladbare Batterien. Teil 1: Akkumulatoren mit wäβriger Elektrolytlösung. Chemie Unserer Zeit 33, 252–266 (1999).

    Article  Google Scholar 

  4. 4.

    Scrosati, B., Garche, J. & Tillmetz, W. Advances in Battery Technologies for Electric Vehicles (Elsevier, 2015).

  5. 5.

    2017 Annual Merit Review, Vehicle Technologies Office (US Department of Energy, 2017);

  6. 6.

    Placke, T., Kloepsch, R., Dühnen, S. & Winter, M. Lithium-ion, lithium metal and alternative rechargeable battery technologies: the odyssey for high energy density. J. Solid State Electrochem. 21, 1939–1964 (2017). This article comprehensively reviews the history of battery technologies and offers perspectives of lithium-ion and post lithium ion batteries.

    Article  Google Scholar 

  7. 7.

    Meister, P. et al. Best practice: performance and cost evaluation of lithium ion battery active materials with special emphasis on energy efficiency. Chem. Mater. 28, 7203–7217 (2016).

    Article  Google Scholar 

  8. 8.

    Andre, D. et al. Future generations of cathode materials: an automotive industry perspective. J. Mater. Chem. A 3, 6709–6732 (2015). This Review describes the requirements for positive active materials (energy density, rate capability, capacity retention, cost and safety) for automotive LIBs from an OEM erspective.

    Article  Google Scholar 

  9. 9.

    Hagen, M. et al. Lithium–sulfur cells: the gap between the state-of-the-art and the requirements for high energy battery cells. Adv. Energy Mater. 5, 1401986 (2015).

    Article  Google Scholar 

  10. 10.

    Gröger, O., Gasteiger, H. A. & Suchsland, J.-P. Review—Electromobility: Batteries or fuel cells? J. Electrochem. Soc. 162, A2605–A2622 (2015).

    Article  Google Scholar 

  11. 11.

    Blomgren, G. E. The development and future of lithium ion batteries. J. Electrochem. Soc. 164, A5019–A5025 (2017).

    Article  Google Scholar 

  12. 12.

    Pillot, C. The Rechargeable Battery Market and Main Trends 2016–2025 (Avicenne Energy, 2017).

  13. 13.

    Winter, M. & Besenhard, J. O. in Handbook of Battery Materials 2nd edn (eds Daniel, C. & Besenhard, J. O.) 433–478 (Wiley VCH, Weinheim, 2011).

  14. 14.

    Korthauer, R. Handbuch Lithium–Ionen–Batterien (Springer Vieweg, Heidelberg, 2013).

  15. 15.

    Juri, G., Wilhelm, H. A. & L’Heureux, J. High-purity graphite powders for high performance. Cfi-Ceramic Forum Int. 84, E22–E25 (2007).

    Google Scholar 

  16. 16.

    Liang, G. & MacNeil, D. D. in Lithium-Ion Batteries: Advanced Materials and Technologies Green Chemistry and Chemical Engineering (eds Yuan, X., Liu, H. & Zhang, J.) 327–394 (CRC Press, Boca Raton, 2011).

  17. 17.

    Dunn, J. B. et al. Material and Energy Flows in the Production of Cathode and Anode Materials for Lithium Ion Batteries (ANL/ESD-14/10 Rev.) (Argonne National Laboratory, 2015). This report gives a comprehensive overview of material flows in the production of anode and cathode materials for lithium ion batteries.

  18. 18.

    Chehreh Chelgani, S., Rudolph, M., Kratzsch, R., Sandmann, D. & Gutzmer, J. A review of graphite beneficiation techniques. Mineral Proc. Extractive Metallurgy Rev. 37, 58–68 (2016).

    Article  Google Scholar 

  19. 19.

    Lämmerer, W. & Flachberger, H. Wissenswertes zur Charakterisierung und Aufbereitung von Rohgrafiten. BHM Berg Hüttenmännische Monatshefte 162, 336–344 (2017).

    Article  Google Scholar 

  20. 20.

    Wiggers, H., Starke, R. & Roth, P. Silicon particle formation by pyrolysis of silane in a hot wall gasphase reactor. Chem. Engineering Technol. 24, 261–264 (2001).

    Article  Google Scholar 

  21. 21.

    Doh, C.-H. et al. A new SiO/C anode composition for lithium-ion battery. J. Power Sources 179, 367–370 (2008).

    Article  Google Scholar 

  22. 22.

    Chen, T., Wu, J., Zhang, Q. & Su, X. Recent advancement of SiOx based anodes for lithium-ion batteries. J. Power Sources 363, 126–144 (2017).

    Article  Google Scholar 

  23. 23.

    Takeda, O. et al. Electrowinning of lithium from LiOH in molten chloride. J. Electrochem. Soc. 161, D820–D823 (2014).

    Article  Google Scholar 

  24. 24.

    Tran, T. & Luong, V. T. in Lithium Process Chemistry: Resources, Extraction, Batteries, and Recycling (eds Chagnes, A. & Swiatowska, J.) 81–124 (Elsevier, 2015).

  25. 25.

    Jónsson, E. Ö. & Larsson, F. Securing Lithium Foil Supply in a Future Imbalanced Market: A Strategy Suggestion for a Prospective Battery Cell Manufacturer (Chalmers University of Technology, 2016).

  26. 26.

    Wietelmann, U. Surface-passivated lithium metal and method for the production thereof. US patent 13,515,579 (2012).

  27. 27.

    Ciez, R. E. & Whitacre, J. F. The cost of lithium is unlikely to upend the price of Li-ion storage systems. J. Power Sources 320, 310–313 (2016).

    Article  Google Scholar 

  28. 28.

    Facada, M. A 21st century lithium rush. Industrial Minerals (4 December 2017).

  29. 29.

    Global Lithium Report (Macquarie Research, 2016).

  30. 30.

    Ryou, M.-H., Lee, Y. M., Lee, Y., Winter, M. & Bieker, P. Mechanical surface modification of lithium metal: towards improved Li metal anode performance by directed Li plating. Adv. Funct. Mater. 25, 825 (2014).

    Article  Google Scholar 

  31. 31.

    Becking, J. et al. Lithium-metal foil surface modification: an effective method to improve the cycling performance of lithium-metal batteries. Adv. Mater. Interfaces 4, 1700166 (2017).

    Article  Google Scholar 

  32. 32.

    Heine, J. et al. Coated lithium powder (CLiP) electrodes for lithium-metal batteries. Adv. Energy Mater. 4, 1300815–1300821 (2013).

    Article  Google Scholar 

  33. 33.

    Obrovac, M. N. & Chevrier, V. L. Alloy negative electrodes for Li-ion batteries. Chem. Rev. 114, 11444–11502 (2014). An in-depth overview of the fundamentals of alloy-based anode materials is reported and comprehensively discussed in view of their practical application in lithium ion full cells.

    Article  Google Scholar 

  34. 34.

    Nitta, N. & Yushin, G. High-capacity anode materials for lithium-ion batteries: choice of elements and structures for active particles. Particle Particle Syst. Characterization 31, 317–336 (2014).

    Article  Google Scholar 

  35. 35.

    Ryu, J., Hong, D., Lee, H.-W. & Park, S. Practical considerations of Si-based anodes for lithium-ion battery applications. Nano Res. 10, 3970–4002 (2017).

    Article  Google Scholar 

  36. 36.

    Holtstiege, F., Wilken, A., Winter, M. & Placke, T. Running out of lithium? A route to differentiate between capacity losses and active lithium losses in lithium-ion batteries. Phys. Chem. Chem. Phys. 19, 25905–25918 (2017).

    Article  Google Scholar 

  37. 37.

    Cheng, X.-B., Zhang, R., Zhao, C.-Z. & Zhang, Q. Toward safe lithium metal anode in rechargeable batteries: A review. Chem. Rev. 117, 10403–10473 (2017).

    Article  Google Scholar 

  38. 38.

    Tikekar, M. D., Choudhury, S., Tu, Z. & Archer, L. A. Design principles for electrolytes and interfaces for stable lithium-metal batteries. Nat. Energy 1, 16114 (2016).

    Article  Google Scholar 

  39. 39.

    Aravindan, V., Lee, Y.-S. & Madhavi, S. Best practices for mitigating irreversible capacity loss of negative electrodes in Li-ion batteries. Adv. Energy Mater. 7, 1602607–1602623 (2017).

    Article  Google Scholar 

  40. 40.

    Janek, J. & Zeier, W. G. A solid future for battery development. Nat. Energy 1, 16141–16144 (2016). This Perspective gives a critical view on the future developments, challenges and limitations of all-solid-state batteries.

    Article  Google Scholar 

  41. 41.

    Myung, S.-T. et al. Nickel-rich layered cathode materials for automotive lithium-ion batteries: achievements and perspectives. ACS Energy Lett. 2, 196–223 (2017).

    Article  Google Scholar 

  42. 42.

    Noh, H.-J., Youn, S., Yoon, C. S. & Sun, Y.-K. Comparison of the structural and electrochemical properties of layered Li[NixCoyMnz]O2 (x = 1/3, 0.5, 0.6, 0.7, 0.8 and 0.85) cathode material for lithium-ion batteries. J. Power Sources 233, 121–130 (2013).

    Article  Google Scholar 

  43. 43.

    Sun, Y.-K., Myung, S.-T., Kim, M.-H., Prakash, J. & Amine, K. Synthesis and characterization of Li[(Ni0.8Co0.1Mn0.1)0.8(Ni0.5Mn0.5)0.2]O2 with the microscale core−shell structure as the positive electrode material for lithium batteries. J. Am. Chem. Soc. 127, 13411–13418 (2005).

    Article  Google Scholar 

  44. 44.

    Lim, B.-B., Myung, S.-T., Yoon, C. S. & Sun, Y.-K. Comparative study of Ni-rich layered cathodes for rechargeable lithium batteries: Li[Ni0.85Co0.11Al0.04]O2 and Li[Ni0.84Co0.06Mn0.09Al0.01]O2 with two-step full concentration gradients. ACS Energy Lett. 1, 283–289 (2016).

    Article  Google Scholar 

  45. 45.

    Whittingham, M. S. Ultimate limits to intercalation reactions for lithium batteries. Chem. Rev. 114, 11414–11443 (2014).This Article discusses various alternative cathode chemistries beyond layered oxides with emphasis on lithium metal phosphates, as well as the ultimate limits of intercalation chemistry with regard to their maximum energy content (Wh kg –1 and Wh l –1 ).

    Article  Google Scholar 

  46. 46.

    Thackeray, M. M., Wolverton, C. & Isaacs, E. D. Electrical energy storage for transportation-approaching the limits of, and going beyond, lithium-ion batteries. Energy Environ. Sci. 5, 7854–7863 (2012).

    Article  Google Scholar 

  47. 47.

    Qiu, B. et al. Gas–solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries. Nat. Commun. 7, 12108 (2016).

    Article  Google Scholar 

  48. 48.

    Schipper, F. et al. Study of cathode materials for lithium-ion batteries: recent progress and new challenges. Inorganics 5, 32 (2017).

    Article  Google Scholar 

  49. 49.

    Bettge, M. et al. Voltage fade of layered oxides: its measurement and impact on energy density. J. Electrochem. Soc. 160, A2046–A2055 (2013).

    Article  Google Scholar 

  50. 50.

    Saubanere, M., McCalla, E., Tarascon, J.-M. & Doublet, M.-L. The intriguing question of anionic redox in high-energy density cathodes for Li-ion batteries. Energy Environ. Sci. 9, 984–991 (2015).

    Article  Google Scholar 

  51. 51.

    Ahmed, S., Nelson, P. A., Gallagher, K. G., Susarla, N. & Dees, D. W. Cost and energy demand of producing nickel manganese cobalt cathode material for lithium ion batteries. J. Power Sources 342, 733–740 (2017).

    Article  Google Scholar 

  52. 52.

    Jugović, D. & Uskoković, D. A review of recent developments in the synthesis procedures of lithium iron phosphate powders. J. Power Sources 190, 538–544 (2009).

    Article  Google Scholar 

  53. 53.

    Yakovleva, M. From Raw Material to Next Generation Advanced Batteries (FMC Corporation, 2017).

  54. 54.

    Chen, Z. H., Qin, Y., Amine, K. & Sun, Y. K. Role of surface coating on cathode materials for lithium-ion batteries. J. Mater. Chem. 20, 7606–7612 (2010).

    Article  Google Scholar 

  55. 55.

    Ewald, B., Krkljus, I. & Lampert, J. K. Method for Producing Electrode Materials. Patent WO2013171059 A1 (2013).

  56. 56.

    Thackeray, M. Lithium-ion batteries: An unexpected conductor. Nat. Mater. 1, 81–82 (2002).

    Article  Google Scholar 

  57. 57.

    Commodity and Metal Prices (Infomine, 2017);

  58. 58.

    Nelson, P., Gallagher, K., Bloom, I. & Dees, D. Modeling the Performance and Cost of Lithium-Ion Batteries for Electric-Drive Vehicles ANL-11/32 (Chemical Sciences and Engineering Division of Argonne National Laboratory, 2011).

  59. 59.

    Simon, B., Ziemann, S. & Weil, M. Potential metal requirement of active materials in lithium-ion battery cells of electric vehicles and its impact on reserves: Focus on Europe. Resour. Conservation Recycling 104, 300–310 (2015).

    Article  Google Scholar 

  60. 60.

    Mineral Commodity Summaries 2017 (US Department of the Interior, US Geological Survey, 2017).

  61. 61.

    Study on the Review of the List of Critical Raw Materials: Non-Critical Raw Materials Factsheets (European Commission, 2017);

  62. 62.

    Xu, K. Electrolytes and interphases in Li-ion batteries and beyond. Chem. Rev. 114, 11503–11618 (2014). This Review provides a still up-to-date summary of liquid electrolytes used in past and current lithium-based batteries including the basic electrolyte and electrode/electrolyte interface theory, for both beginners and experts.

    Article  Google Scholar 

  63. 63.

    Schmitz, R. W. et al. Investigations on novel electrolytes, solvents and SEI additives for use in lithium-ion batteries: Systematic electrochemical characterization and detailed analysis by spectroscopic methods. Prog. Solid State Chem. 42, 65–84 (2014).

    Article  Google Scholar 

  64. 64.

    Zhang, S. S. A review on electrolyte additives for lithium-ion batteries. J. Power Sources 162, 1379–1394 (2006).

    Article  Google Scholar 

  65. 65.

    Xu, K. Nonaqueous liquid electrolytes for lithium-based rechargeable batteries. Chem. Rev. 104, 4303–4417 (2004).

    Article  Google Scholar 

  66. 66.

    Pacheco, M. A. & Marshall, C. L. Review of dimethyl carbonate (DMC) manufacture and its characteristics as a fuel additive. Energy Fuels 11, 2–29 (1997).

    Article  Google Scholar 

  67. 67.

    Raines, D. A. & Ainsworth, O. C. Ethylene carbonate process. US patent 4233,221 (1979).

  68. 68.

    Garcia-Herrero, I. et al. Environmental assessment of dimethyl carbonate production: Comparison of a novel electrosynthesis route utilizing CO2 with a commercial oxidative carbonylation process. ACS Sustain. Chem. Engineer 4, 2088–2097 (2016).

    Article  Google Scholar 

  69. 69.

    Naitou, T. et al. Method of manufacturing diethyl carbonate. US patent 20,150,291,504 A1 (2015).

  70. 70.

    Inaba, M. et al. Process for producing unsymmetrical chain carbonic acid ester. US patent 5,760,273 A (1998).

  71. 71.

    Na, D. C., Woo, B. W., Park, S. H. & Lee, J. H. Manufacturing method for lithium hexafluoro phosphate. US patent 6,387,340 B1 (2002).

  72. 72.

    Lu, H. L. Present Technology and Market Development Trends of Electrolyte and Separator for LIB (Second International Forum on Electrolyte & Separator for Advanced Batteries, 2015).

  73. 73.

    Kasnatscheew, J. et al. Determining oxidative stability of battery electrolytes: validity of common electrochemical stability window (ESW) data and alternative strategies. Phys. Chem. Chem. Phys. 19, 16078–16086 (2017).

    Article  Google Scholar 

  74. 74.

    Lebedeva, N. P. & Boon-Brett, L. Considerations on the chemical toxicity of contemporary Li-ion battery electrolytes and their components. J. Electrochem. Soc. 163, A821–A830 (2016).

    Article  Google Scholar 

  75. 75.

    Nowak, S. & Winter, M. Review—chemical analysis for a better understanding of aging and degradation mechanisms of non-aqueous electrolytes for lithium ion batteries: method development, application and lessons learned. J. Electrochem. Soc. 162, A2500–A2508 (2015).

    Article  Google Scholar 

  76. 76.

    Lee, H., Yanilmaz, M., Toprakci, O., Fu, K. & Zhang, X. A review of recent developments in membrane separators for rechargeable lithium-ion batteries. Energy Environ. Sci. 7, 3857–3886 (2014). This Article gives an in-depth overview of the recent developments, characteristics and production processes of membrane separators for lithium ion batteries, in addition to covering the field of solid electrolytes.

    Article  Google Scholar 

  77. 77.

    Arora, P. & Zhang, Z. M. Battery separators. Chem. Rev. 104, 4419–4462 (2004).

    Article  Google Scholar 

  78. 78.

    Bachman, J. C. et al. Inorganic solid-state electrolytes for lithium batteries: mechanisms and properties governing ion conduction. Chem. Rev. 116, 140–162 (2016).

    Article  Google Scholar 

  79. 79.

    Motavalli, J. Technology: a solid future. Nature 526, S96–S97 (2015).

    Article  Google Scholar 

  80. 80.

    Rodrigues, M.-T. F. et al. A materials perspective on Li-ion batteries at extreme temperatures. Nat. Energy 2, 17108 (2017).

    Article  Google Scholar 

  81. 81.

    Manthiram, A., Yu, X. & Wang, S. Lithium battery chemistries enabled by solid-state electrolytes. Nat. Rev. Mater. 2, 16103 (2017).

    Article  Google Scholar 

  82. 82.

    Anderman, M. xEV Expansion, Key Technology, and Market Development (Total Battery Consulting, 2017).

  83. 83.

    Cekic-Laskovic, I. et al. Synergistic effect of blended components in nonaqueous electrolytes for lithium ion batteries. Topics Current Chem. 375, 37 (2017).

    Article  Google Scholar 

  84. 84.

    Gambe, Y., Sun, Y. & Honma, I. Development of bipolar all-solid-state lithium battery based on quasi-solid-state electrolyte containing tetraglyme-LiTFSA equimolar complex. Sci. Rep. 5, 8869 (2015).

    Article  Google Scholar 

  85. 85.

    Kim, C. R., Tajitsu, N. & Nussey, S. Toyota set to sell long-range, fast-charging electric cars in 2022: paper. Reuters (25 July 2017).

  86. 86.

    Manthiram, A., Fu, Y., Chung, S.-H., Zu, C. & Su, Y.-S. Rechargeable lithium–sulfur batteries. Chem. Rev. 114, 11751–11787 (2014).

    Article  Google Scholar 

  87. 87.

    Bruce, P. G., Freunberger, S. A., Hardwick, L. J. & Tarascon, J. M. Li–O2 and Li–S batteries with high energy storage. Nat. Mater. 11, 19–29 (2012).

    Article  Google Scholar 

  88. 88.

    Judez, X. et al. Review—Solid electrolytes for safe and high energy density lithium–sulfur batteries: promises and challenges. J. Electrochem. Soc. 165, A6008–A6016 (2018).

    Article  Google Scholar 

  89. 89.

    Freunberger, S. A. True performance metrics in beyond-intercalation batteries. Nat. Energy 2, 17091 (2017). This Comment highlights the importance of reporting complete experimental data sets and objectifies the comparison between intercalation and post-intercalation chemistries.

    Article  Google Scholar 

  90. 90.

    Gallagher, K. G. et al. Quantifying the promise of lithium-air batteries for electric vehicles. Energy Environ. Sci. 7, 1555–1563 (2014).

    Article  Google Scholar 

  91. 91.

    Nykvist, B. & Nilsson, M. Rapidly falling costs of battery packs for electric vehicles. Nat. Clim. Change 5, 329–332 (2015).

    Article  Google Scholar 

  92. 92.

    Sauer, D. U. Don’t wait for the next battery-cell generation. ATZelektronik Worldwide 11, 72–72 (2016).

    Article  Google Scholar 

  93. 93.

    Copper (Eco3e, 2016);

  94. 94.

    Helbig, C., Bradshaw, A. M., Wietschel, L., Thorenz, A. & Tuma, A. Supply risks associated with lithium-ion battery materials. J. Cleaner Prod. 172, 274–286 (2018).

    Article  Google Scholar 

  95. 95.

    Reuter, B. Assessment of sustainability issues for the selection of materials and technologies during product design: a case study of lithium-ion batteries for electric vehicles. Int. J. Interactive Design Manufactur 10, 217–227 (2016).

    Article  Google Scholar 

  96. 96.

    Berg, E. J., Villevieille, C., Streich, D., Trabesinger, S. & Novák, P. Rechargeable batteries: grasping for the limits of chemistry. J. Electrochem. Soc. 162, A2468–A2475 (2015).

    Article  Google Scholar 

  97. 97.

    Patry, G., Romagny, A., Martinet, S. & Froelich, D. Cost modeling of lithium-ion battery cells for automotive applications. Energy Sci. Engineer 3, 71–82 (2014).

    Article  Google Scholar 

  98. 98.

    Nelson, P., Gallagher, K. & Bloom, I. BatPaC (Battery Performance and Cost) Software (Argonne National Lab, accessed 10 August 2017); This Article offers an in-depth, spreadsheet-based, regularly updated calculation tool to estimate cost and energy density of various battery designs following a bottom-up approach.

Download references


The authors thank the German Federal Ministry of Education and Research (BMBF) for funding this work in the project, BenchBatt (03XP0047A). We thank A. Bar for the preparation of various figures in this manuscript. We further want to thank the Treofan Germany & Co KG (F. J. Kruger) for support with regard to the separator production processes.

Author information



Corresponding authors

Correspondence to Tobias Placke or Martin Winter.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Schmuch, R., Wagner, R., Hörpel, G. et al. Performance and cost of materials for lithium-based rechargeable automotive batteries. Nat Energy 3, 267–278 (2018).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing