Reversible sodiation of electrochemically deposited binder- and conducting additive-free Si-O-C composite layers

Affiliation
Institute for Sensor and Actuator Technology Hochschule für Angewandte Wissenschaften Coburg 96450 Coburg Germany
Link, Steffen;
Affiliation
Institute of Physics and Institute of Micro- and Nanotechnologies MacroNano Technische Universität Ilmenau 98693 Ilmenau Germany
Dimitrova, Anna;
Affiliation
Institute of Physics and Institute of Micro- and Nanotechnologies MacroNano Technische Universität Ilmenau 98693 Ilmenau Germany
Krischok, Stefan;
ORCID
0000-0003-0993-9412
Affiliation
Electrochemistry and Electroplating Group Technische Universität Ilmenau 98693 Ilmenau Germany
Ivanov, Svetlozar

Binder- and conducting additive-free Si-O-C composite layers are deposited electrochemically under potentiostatic conditions from sulfolane-based organic electrolyte. Quartz crystal microbalance with damping monitoring is used for evaluation of the layer growth and its physical properties. The sodiation-desodiation performance of the material is afterward explored in Na-ion electrolyte. In terms of specific capacity, rate capability, and long-term electrochemical stability, the experiments confirm the advantages of applying the electrochemically formed Si-O-C structure as anode for Na-ion batteries. The material displays high (722 mAh g^-1) initial reversible capacity at j = 70 mA g^-1 and preserves stable long-term capacity of 540 mAh g^-1 for at least 400 galvanostatic cycles, measured at j = 150 mA g^-1. The observed high performance can be attributed to its improved mechanical stability and accelerated Na-ion transport in the porous anode structure. The origin of the material electroactivity is revealed based on X-Ray photoelectron spectroscopic analysis of pristine (as deposited), sodiated, and desodiated Si-O-C layers. The evaluation of the spectroscopic data indicates reversible activity of the material due to the complex contribution of carbon and silicon redox centers.

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