(Invited) Coordinatively Cross-Linked Binders for Silicon-Based Electrodes for Lithium Ion Batteries

Abstract

We have proposed a simple and versatile preparation of Cu(II)- or Zn(II)-poly(carboxylates) reticulated binders by the addition of Cu(II) or Zn(II) precursors into a pre-optimized carboxymethyl cellulose / citric acid binder solution. These binders lead systematically to a significantly improved electrochemical performance when used for the formulation of silicon-based negative electrodes [1,2]. Mechanical characterizations reveal that the coordinated binders offer a better electrode coating cohesion and adhesion to the current collector, as well as higher hardness and elastic modulus, which are even preserved in presence of a carbonate solvent (i.e. in battery operation conditions). Ultimately, as shown from operando dilatometry experiments, the electrode expansion during lithiation is reduced, mitigating electrode mechanical failure [2]. In complement, we used scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy to probe the nanoscale morphology of such electrodes. This technique reveals the homogeneous coordination of carboxylated binder with Zn cations and its layering on the silicon surface. The SEI formed after the first cycle is denser with Zn-coordinated binder and preferentially observed on binder-depleted zones [3]. In summary, the superiority of coordinated binders can be attributed to their capacity to better stabilize the electrode and the SEI layer due to improved mechanical properties. This resulted in a lower SEI impedance, a higher first cycle coulombic efficiency, and a 40% improvement of capacity retention after 60 cycles for highly loaded electrodes of over 6 mAh.cm-2. Noteworthy, this formulation principle allows for better reproducibility and manufacturing quality of the electrodes [4].[1] D. Mazouzi, R. Grissa, M. Paris, Z. Karkar, L. Huet, D. Guyomard, L. Roué, T. Devic, B. Lestriez, Electrochimica Acta, 304 (2019) 495-504[2] L. Huet, D. Mazouzi, P. Moreau, N. Dupré, M. Paris, S. Mittelette, D. Laurencin, T. Devic, L. Roué, B. Lestriez, ACS Applied Materials & Interfaces, 15 (2023) 15509-15524[3] L. Huet, P. Moreau, N. Dupré, T. Devic, L. Roué, B. Lestriez, Small Methods, 2022, 2200827[4] L. Huet, H. Houisse, N. Herkendaal, T. Devic, L. Roué, B. Lestriez, Energy Technology, 2023, 2201483 Figure 1