10.0: Introduction

Keeping Energy in Check: The Thermodynamics Behind Safer Batteries

                                           

Figure \(\PageIndex{1}\): A graphic with basic facts about Shirley Meng, materials chemist who has made amazing discoveries regarding solid-state batteries. Dr. Meng is a professor at the University of Chicago Pritzker School of Molecular Engineering and chief scientist at the Argonne Collaborative Center for Energy Storage Science (ACCESS) at the Argonne National Laboratory. Image from University of Chicago Pritzker School of Molecular Engineering; copyright 2025 University of Chicago.

Thermodynamics is the study of energy and its transformations. These principles help us understand whether a reaction will proceed and, if so, under what conditions. Although thermodynamics was originally developed to improve the efficiency of steam engines, its applications extend far beyond engines to include chemical reactions, biological processes, phase changes, refrigeration, and batteries.

Batteries are central to sustainable energy strategies, but current technologies are not yet capable of meeting global energy demands. Dr. Shirley Meng, a leading scientist in energy storage materials, is applying thermodynamic principles to help design next-generation solid-state, anode-free batteries. These batteries offer the promise of higher energy density, fewer safety risks, and faster charging compared to the traditional lithium-ion models used in today’s electronics. Achieving that promise, however, requires mastering the thermodynamics of solid-solid interfaces, phase transitions, and ion mobility. 

In conventional batteries, liquid electrolytes make good contact with the current collector (the part of the battery that conducts electrons to the external circuit), which helps the battery function efficiently. Over time, however, the liquid can break down and react with other materials in the battery. This creates unwanted buildup at the interface (where different battery components meet) which slowly consumes the active materials and reduces the battery's capacity. Solid-state batteries avoid this problem by using a solid electrolyte instead of a liquid one, but it is more difficult for the solid to maintain good contact with the current collector, creating a new challenge for battery design.

 

Figure \(\PageIndex{2}\): A schematic diagram of the difference between a standard battery and an anode-free battery. A standard battery consists of a cathode (a negatively charged electrode) and an anode (a positively charged electrode) separated by an electrolyte (a material containing ions), with a current collector (to connect to the external circuit) at each end. An anode-free battery has the same components except for the anode, because the anode is actually formed during the first charge cycle. This reduces material costs and allows batteries to be made smaller. Reprinted from with permission from Zhu et al. 2021, Nano Letters 21(3). Copyright 2025 American Chemical Society.

Dr. Meng and her research team use advanced computational tools to predict the structure of materials that are dense, make effective contact with the current collector, and are thermodynamically stable. In 2024, her group published design principles for these materials and demonstrated a sodium-containing solid-state battery material that can withstand over 400 charge cycles without significantly diminishing capacity. Her research shows how exploring new materials and characterizing their thermodynamic properties can improve battery lifespan, power, and safety, helping to prevent short circuits, fires and explosions.

By replacing scarce lithium with abundant sodium and improving performance through thermodynamic insight, Meng’s work is paving the way for safer, more sustainable energy storage. Her research shows how thermodynamic properties like entropy and enthalpy, which describe the behaviour of materials at the atomic level, influence the performance and stability of real-world batteries.  In this chapter, we will explore these same fundamental laws of thermodynamics.

Sources:

1. Banerjee, A.; Wang, X.; Fang, C.; Wu, E. A.; Meng, Y. S. Interfaces and Interphases in All-Solid-State Batteries with Inorganic Solid Electrolytes. Chem. Rev. 2020, 120 (14), 6878–6933. https://doi.org/10.1021/acs.chemrev.0c00101.
2. Cronk, A.; Chen, Y.-T.; Deysher, G.; Ham, S.-Y.; Yang, H.; Ridley, P.; Sayahpour, B.; Nguyen, L. H. B.; Oh, J. A. S.; Jang, J.; Tan, D. H. S.; Meng, Y. S. Overcoming the Interfacial Challenges of LiFePO4 in Inorganic All-Solid-State Batteries. ACS Energy Lett. 2023, 8 (1), 827–835. https://doi.org/10.1021/acsenergylett.2c02138.
3. Deysher, G.; Oh, J. A. S.; Chen, Y.-T.; Sayahpour, B.; Ham, S.-Y.; Cheng, D.; Ridley, P.; Cronk, A.; Lin, S. W.-H.; Qian, K.; Nguyen, L. H. B.; Jang, J.; Meng, Y. S. Design Principles for Enabling an Anode-Free Sodium All-Solid-State Battery. Nat Energy 2024, 9 (9), 1161–1172. https://doi.org/10.1038/s41560-024-01569-9.
4. Meng, S. Laboratory for Energy Storage and Conversion. LESC. https://lescmeng.ai/.
5. Wilke, C. Zinc-ion batteries could reach higher energy densities by avoiding a traditional anode. Chemical & Engineering News. https://cen.acs.org/materials/energy-storage/Zinc-ion-batteries-reach-higher/99/i5.
6. Zhu, Y.; Cui, Y.; Alshareef, H. N. An Anode-Free Zn–MnO2 Battery. Nano Lett. 2021, 21 (3), 1446–1453. https://doi.org/10.1021/acs.nanolett.0c04519.
7.  A Look Inside Your Battery: Watching the Dendrites Grow – Battery Power Online. https://www.batterypoweronline.com/news/a-look-inside-your-battery-watching-the-dendrites-grow/.
8.  Y. Shirley Meng | Pritzker School of Molecular Engineering | The University of Chicago. https://pme.uchicago.edu/faculty/y-shirley-meng.
9.  UChicago Prof. Shirley Meng’s Laboratory for Energy Storage and Conversion creates world’s first anode-free sodium solid-state battery – a breakthrough in inexpensive, clean, fast-charging batteries | Pritzker School of Molecular Engineering | The University of Chicago. https://pme.uchicago.edu/news/uchicago-prof-shirley-mengs-laboratory-energy-storage-and-conversion-creates-worlds-first.