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Titel:

CFP2022-926

Dual lithium salts mediated lithium transfer in viscous cellulose acetate gel-polymer electrolyte
Poster Exhibition
Electrolytes & separators
Performance

Lithium-ion Batteries (LIBs) have reached great importance in many markets and influence our daily life. Due to increase in demand for the batteries with high energy density and flexibility, aspects such as safety, reliability, costs and sustainability get in focus. Replacement of conventional carbonate-based liquid electrolytes towards more environmentally friendly, safe, and sustainable polymer electrolytes (PEs) is an effective strategy. Developments in the field of PEs were mainly focused on solvent-free solid polymer electrolyts (SPEs) and on improving the intrinsic low ionic conductivity, narrow electrochemical stability window (ESW) and high interfacial resistance to make Lithium solid polymer batteries (LSPB) into a practical reality. Beyond these challenges, higher mechanical and higher thermal stability along with reduced growth of dendrites are considered as the requirements for the application of polymer electrolytes. In this context cross-linked environmentally friendly gel-polymer electrolytes (GPE) with natural sustainable resources like cellulose derivatives can meet the requirements and thus, considered to be a suitable candidate for next generation LIBs. Instead of approaches such as synthezising SPEs, a cellulose acetate matrix is integrated as the basis of the electrolyte in a cyclic propylene carbonate (PC) environment with a multi salt approach, so that a GPE is formed. This swollen polymer matrix preserves the cohesion properties of a solid as well as the diffusion properties of a liquid. Thus, this GPE shows good mechanical, chemical, electrochemical and structural stability, as well as a sufficient ionic conductivity. Beyond the cellulose acetate based GPE eliminate safety concerns concerning the risk of leakage, due to its highly viscous properties. Although there is a much higher viscosity of the GPEs (50 – 80 Pa s) compared to liquid electrolytes like LP57 (0.71 mPa s), ionic conductivity of 3.6 mS cm-1 (LP57: 7.7 mS cm-1) is achieved at 20°C with dual lithium salts LiTFSI and LiBOB along with the cross-linked cellulose acetate. To evaluate the electrochemical performance, coin cells were assembled using NMC622 (LiNi0.6Mn0.2Co0.2O2) as cathode material and SG3 (synthetic graphite) as anode material.

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Co-Autoren

Mika Hellkuhl, Tobias Placke, Martin Winter