Graphite//LiNi_0.5Mn_1.5O₄ Cells Based on Environmentally Friendly Made-in-Water Electrodes

Graphical Abstract

Eco-friendly high-energy batteries: The stability of high-energy graphite// LiNi_0.5Mn_1.5O₄ (LNMO) cells featuring electrodes made through aqueous processing is demonstrated for the first time by long-term cycling in a carbonate-based electrolyte. The made-in-water LNMO cathode outperforms an LNMO with polyvinylidene fluoride binder, showing an enhanced cycling stability resulting from the beneficial effects of the sodium carboxymethyl cellulose (CMC) binder.

Abstract

The performance of graphite//LiNi_0.5Mn_1.5O₄ (LNMO) cells, both electrodes of which are made using water-soluble sodium carboxymethyl cellulose (CMC) binder, is reported for the first time. The full cell performed outstandingly over 400 cycles in the conventional electrolyte ethylene carbonate/dimethyl carbonate–1 m LiPF₆, and the delivered specific energy at the 100th, 200th, 300th, and 400th cycle corresponded to 82, 78, 73, and 66 %, respectively, of the initial energy value of 259 Wh kg⁻¹ (referring to the sum of the two electrode-composite weights). The good stability of high-voltage, LNMO–CMC-based electrodes upon long-term cycling is discussed and the results are compared to those of LNMO-composite electrodes with polyvinylidene fluoride (PVdF). LNMO–CMC electrodes outperformed those with PVdF binder, displaying a capacity retention of 83 % compared to 62 % for the PVdF-based electrodes after 400 cycles at 1 C. CMC promotes a more compact and stable electrode surface than PVdF; undesired interfacial reactions at high operating voltages are mitigated, and the thickness of the passivation layer on the LNMO surface is reduced, thereby enhancing its cycling stability.