Summary The effects of solvent absorption on the electrochemical and mechanical properties of polymer electrolytes for use in solid-state batteries have been measured by researchers since the 1980s. These studies have shown that small amounts of absorbed solvent may increase ion mobility and decrease crystallinity in these materials. Even though many polymers and lithium salts are hygroscopic, the solvent content of these materials is rarely reported. As ppm-level solvent content may have important consequences for the lithium conductivity and crystallinity of these electrolytes, more widespread reporting is recommended. Here we illustrate that ppm-level solvent content can significantly increase ion mobility, and therefore the reported performance, in solid polymer electrolytes. Additionally, the impact of absorbed solvents on other battery components has not been widely investigated in all-solid-state battery systems. Therefore, comparisons will be made with systems that use liquid electrolytes to better understand the consequences of absorbed solvents on electrode performance.

We reproducibly quantify water content in different SPE systems through the various processing/drying conditions and we tie the residual amounts of water to heightened ionic conductivities. Moreover, we emphasise on...

For the first time, a one-pot synthesis of LiAlO2-coated LiNi0.6Mn0.2Co0.2O2 particles using a continuous stirred-tank reactor is reported. Two methods of surface coating were compared with the pristine sample. The...

In the modern world, the rapid advancement of new technologies is accompanied by an increasing energetic demand. Following today`s trend, energy consumption will undoubtedly increase in the following years. Over the last 50 years, lithium-metal batteries have been considered as potential candidates for long-term high-performance electrochemical storage. (1) Although their operation is effective, they still present limitations mainly due to lithium dendrite growth associated with electrodeposited Li+ from the electrolyte on the anode material. This phenomenon causes internal short-circuits resulting in premature battery failure. (2) Various solid-state battery systems are being developed in hope to resolve the said issue. Amongst others, solid polymer electrolytes (SPE) have been investigated since Armand`s work in the 80`. (3) Even though these systems have non-flammable properties and successfully suppress dendrite growth, most SPEs do not reach ionic conductivities values higher than 10-3 S/cm at room temperature and offer lower energy densities and cycle number compared to the standard liquid electrolyte counterpart. (4) As a result of that, an increasing number of published literature shows off new engaging SPE systems. However, oftentimes, the presented performances are hardly reproducible due to the lack of precise and detailed experimental conditions. It is believed that some overlooked factors during processing may affect the aforementioned performances. (5-7) Certain parameters that affect ionic conductivities of SPEs have been investigated by techniques including but not limited to electrochemical impedance spectroscopy (EIS) and solid-state 7Li-NMR. It will be demonstrated that these parameters must be precisely controlled to ensure the reproducibility and the validity of measurements. Finally, it will be shown that this study can be applied to several types of polymers. 1: Hall P. J., Bain E. J., Energy Policy, 36, 4352 (2008). 2: Lisbona D., Snee T., Process. Saf. Environ., 89, 434 (2011). 3: Armand M. B., Ann. Rev. Mater. Sci. 16, 245 (1986). 4: Penghui Y., Haobin Y., Zhiyu D., Yanchen L., Juan L., Marino L., Junwei W., Xingjun L., Front. Chem., 7, 522 (2019). 5: Fullerton-Shirey S. K., Maranas J.K, Macromolecules, 42, 2142 (2009). 6: Devaux D., Bouchet R., Glé D., Denoyel R., Solid State Ion., 227, 119 (2012). 7: Wang X., Zhang L., Li G., Zhang G., Shao Z.G., Yi B., Electrochim. Acta, 158, 253 (2015)

In the context of the urgent modern energy challenges, lithium-metal (LMB) and lithium-ion batteries (LIB) are conceivable candidates for long term electrochemical storage of renewable energies. As such, while many possible electrolytes are being investigated, solid polymer electrolytes (SPE) are potential replacements for the classic liquid electrolytes that are used in today’s commercial LIB developed and patented by Sony Energitech in 1991. Despite offering non-flammable properties, eliminating the need for heavy casings and allowing the use of higher-energy density lithium at the anode, these electrolytes still suffer from low ionic conductivities. Therefore, plenty of novel SPE systems are being developed and proposed for their captivating properties. Oftentimes, these systems seem appealing but are hardly reproducible in laboratory settings, basing oneself solely upon the published experimental conditions. An interesting inter-laboratory study was published, in which the same thiophosphate ceramic-based solid electrolyte samples were distributed across 11 different research groups. The relative standard deviation calculated from reported conductivities reached a value of 50%. (1) Recently, it has been shown that different post-drying procedures influenced the water content of electrodes which in turn affected the electrochemical properties of LIBs. (2) In SPEs, amongst different factors that could affect ionic conductivities, we believe that water plays a non-neglectable role. Knowing that relative humidity is strongly affected by the local climate, conditions can vary from laboratory to laboratory from a day to another. Being a factor that isn’t controlled effortlessly, samples’ water content can easily be overlooked. However, only a few recent papers mention that matter.(3) The issue is that on one hand, even though some authors reported enhanced ionic conductivities with an increased water content of SPEs, others claim the opposite to be true, which makes the subject ambiguous.(4) On the other hand, very few SPE systems have been studied, which makes the effect of water unclear. In this study, three different types of polymers, poly(ethylene oxide) (PEO), poly(acrylonitrile) (PAN), and acrylonitrile methyl acrylate copolymer latex (AMAC), two different lithium salts (LiTFSI and LiClO4), and two different processing methods (Wet solution casting and solvent-free dry mixing) have been used to prepare different SPE samples. Samples of PEO-LiTFSI, PAN-LiClO4, and AMAC-LiTFSI with different water contents have been prepared and analysed following a strict reproducible drying/doping protocol. Different electrochemical parameters such as the ionic conductivity, the activation barrier and the electrochemical stability window have been assessed in different samples and correlated to their respective water contents. It has been shown that water does indeed influence SPEs and that it’s a factor that needs to be taken into consideration for reproducibility purposes. 1: S.Ohno, T. Bernges, J. Buchheim, M. Duchardt, A. K. Hatz, M. A. Kraft, H. Kwak, A. L. Santhosha, Z. Liu, N. Minafra, F. Tsuji, A. Sakuda, R. Schlem, S. Xiong, Z. Zhang, P. Adelhelm, H. Chen, A. Hayashi, Y. S. Jung, B. V. Lotsch, B. Roling, N. M. Vargas-Barbosa, W. G. Zeier, ACS Energy Lett., 5, 910-915 (2020). 2: F. Huttner, W. Haselrieder, A. Kwade, Energy Technol., 8, 1900245 (2020). 3: B. Commarieu, A. Paolella, S. Collin-Martin, C. Gagnon, A. Vijh, A. Guerfi, K. Zaghib, J. Power Sources, 436, 226852 (2019). 4: M. Z. Munshi, B. B. Owens, Appl. Phys. Commun., 8 (1987). TOTAL Classification: Restricted Distribution TOTAL - All rights reserved

The chemistry of lithium-ion batteries (LIBs) is an active area of research, notably through the increasing demand for high energy and power density in LIBs, especially for application in electric vehicles (EVs) and hybrid electric vehicles (HEVs). Among the various cathode materials, LiNixCoyMn1-x-yO2 (NMC) intercalation compounds are the best candidates for applications in high performance LIBs. However, Ni-rich NMC suffers mainly from parasitic side reactions at the interface with the electrolyte, which leads to a lower thermal and electrochemical stability. Surface modification via coating is an effective concept to counter the capacity degradation of NMC and to improve the particles’ structural stability for enhancing their cycle-life [1], [2]. Different processing techniques that usually requires several steps are presented in the literature. However, to facilitate the integration of a new product in the current battery market, it is preferable to reduce the number of steps during the synthesis process. In this work, we propose a one-pot synthesis of LiAlO2-coated LiNi0.6Mn0.2Co0.2O2 particles, by using a continuous stirred-tank reactor (CSTR). Firstly, the composition and morphology of the coated and uncoated cathode materials are characterized by SEM, TEM, EDX and XPS. Then, the structural characterization of our materials is validated by XRD analysis. Consequently, we will compare the electrochemical performance and thermal stability of coated and uncoated NMC particles. We will demonstrate that our approach provides an easy way to apply surface treatment onto Ni-rich NMC particles and simplifies the synthesis process at large scale production. KEYWORDS: Lithium-ion battery, Ni-rich NMC cathode, LiAlO2 coating, surface protection. Negi, R.S., et al., Enhancing the Electrochemical Performance of LiNi0.70Co0.15Mn0.15O2 Cathodes Using a Practical Solution-Based Al2O3 Coating. ACS Applied Materials & Interfaces, 2020. 12(28): p. 31392-31400. Kim, H.-S., et al., Enhanced electrochemical properties of LiNi1/3Co1/3Mn1/3O2 cathode material by coating with LiAlO2 nanoparticles. Journal of Power Sources, 2006. 161(1): p. 623-627.