Bio-based Polymers for Lithium Polymer Batteries

As fossil fuel sources diminish and the harm they cause to the environment increases, the storage and effective utilization of energy obtained from alternative energy sources (solar, wind, water, etc.) has become critically important.

Batteries store energy and enable the conversion of chemical energy into electrical energy, particularly in mobile devices. Due to the growing use of electrically powered mobile devices (mobile phones, electric vehicles, etc.), the battery market continues to expand, with a projected size of USD 92 billion as a 2025 target. Batteries are divided into non-rechargeable primary cells and rechargeable secondary cells. Due to the increase in portable devices, batteries used in these devices are expected to be flexible, lightweight, energy-dense, high-capacity, long-lasting, and highly safe. Although many battery types have been developed for this reason, lithium-ion batteries stand out because they offer these properties and are economical. Lithium-ion batteries consist of organic solvents (ethylene carbonate, propylene carbonate, diethyl carbonate, etc.) in which lithium salts are dissolved, and a separator that separates the positive and negative electrodes from each other. Lithium ions migrate between the positive and negative electrodes during charging and discharging.

In recent years, interest in lithium-ion polymer batteries has increased due to safety problems (heating, short circuits, explosions, combustion, etc.) caused by the solvents that dissolve lithium salts in lithium-ion batteries.

[caption id="attachment_104832" align="alignnone"] Figure 1. Examples of solid polymer electrolytes [Ref 9.][/caption]In lithium-ion polymer batteries, lithium ions are located within the polymer matrix. The polymer matrix consists of polymers such as poly(ethylene oxide) (PEO), poly(acrylonitrile) (PAN), poly(methyl methacrylate) (PMMA), or poly(vinylidene fluoride) (PVdF). Polymer electrolytes can be classified into three types: solid, gel, and porous. In lithium-ion polymer batteries, ionic conductivity is provided by the polymer, and for high ionic conductivity, the polymer must have a low glass transition temperature (Tg). However, this reduces mechanical strength. For this reason, the use of cross-linked polymer network structures that enhance mechanical strength as the polymer matrix alongside polymers with high ionic conductivity and low Tg values has become critically important. Another method to increase mechanical strength is the use of clays and nanomaterials. Due to the recent depletion of petroleum derivatives and emerging environmental concerns, the use of bio-based chemicals as an alternative to petroleum-derived chemicals has become important. With the use of bio-based polymers in lithium-ion batteries, more environmentally friendly and healthier batteries can be developed. [caption id="attachment_104833" align="aligncenter"] Figure 2. Preparation of solid polymer electrolytes from bio-based polymers [Ref 10.][/caption]İzel Kimya produces polymers in which many bio-based chemicals are used as raw materials. In particular, our company, which manufactures single-component and two-component acrylic resins, is conducting studies aimed at developing acrylic resins with different properties. Our ongoing research focuses on obtaining polymer matrices from acrylic monomers modified with lithium salts for use as polymer electrolytes in lithium-ion batteries and determining the ionic conductivity capacities of polymer electrolytes.

References 1) https://tr.wikipedia.org/wiki/Lityum_polimer_pil 2) Arya, A., Sharma, A.L. Polymer electrolytes for lithium ion batteries: a critical study. Ionics 23, 497–540 (2017). 3) Shin, W., Cho, J., Kannan, A. et al. Cross-linked Composite Gel Polymer Electrolyte using Mesoporous MethacrylateFunctionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries. Sci Rep 6, 26332 (2016) 4) C.M. Costa, E. Lizundia, S. Lanceros-Méndez, Polymers for advanced lithium-ion batteries: State of the art and future needs on polymers for the different battery components, Progress in Energy and Combustion Science, Volume 79,2020.

5) Jimin Shim, Lucia Kim, Hee Joong Kim, Daun Jeong, Jin Hong Lee, Jong-Chan Lee, All-solid-state lithium metal battery with solid polymer electrolytes based on polysiloxane crosslinked by modified natural gallic acid, Polymer, Volume 122, 2017. 6) Xia, Shuixin et al. Practical Challenges and Future Perspectives of All-Solid-State Lithium-Metal Batteries, Chem, Volume 5, Issue 4, 753 - 785. 7) Qingfeng Zhai, Fuwei Xiang, Fang Cheng, Yongjiang Sun, Xiaoping Yang, Wen Lu, Liming Dai, Recent advances in flexible/stretchable batteries and integrated devices, Energy Storage Materials, Volume 33, 2020. 8) Schon, T.B., Tilley, A.J., Bridges, C.R., Miltenburg, M.B. and Seferos, D.S. (2016), Bio-Derived Polymers for Sustainable Lithium-Ion Batteries. Adv. Funct. Mater., 26: 6896-6903. 9) Zhao, Q., Stalin, S., Zhao, C. et al. Designing solid-state electrolytes for safe, energy-dense batteries. Nat Rev Mater 5, 229–252 (2020). 10) Tuan. Naiwi, T.S.R.; Aung, M.M.; Ahmad, A.; Rayung, M.; Su'ait, M.S.; Yusof, N.A.; Wynn Lae, K.Z. Enhancement of Plasticizing Effect on Bio-Based Polyurethane Acrylate Solid Polymer Electrolyte and Its Properties. Polymers 2018, 10, 1142.

Dr. Cemil Dızman Research and Development Director İzel Kimya Gökhan Yıldırım Research and Development Researcher İzel Kimya