Abstract
UDC 541.136
Balastless thin-layer MnO2/Al-electrodes without electronconducting carbon additive and those but in the combination with multi-walled carbon nanotubes (MWCNTs) MnO2/Al-MWCNTs, as well as the bulk-modified paste electrodes MnO2, MWCNTs, and stainless steel electrodes have been investigated in the redox reaction with lithium in a model accumulator оn the base of propylene carbonate (PC), dimetoxiethane (DME), 1M LiClO4 and of ethyl carbonate (EC), dimethyl carbonate (DMC), 1M LiClO4 electrolytes. The window of the electrochemical stability to the anode oxidation on MnO2, and MWCNTs electrodes in the work range of the potentials for the investigated electrolytes is equal to 2.0–4.1 and 2.0–4.2 V, respectively. Because of a high contact resistence of the particles of a thin-layer β/γ-MnO2/Al electrode its discharge capacity cannot be over 110–120 mAh/g, but it is stable during 180 cycles. The discharge capacity of MnO2, MWCNTs electrodes during the first cycle reaches 265–280 mАh/g, the reversible one – (185–250) mАh/g in the first 50 cycles. The role of the aluminum collector in the electrochemical transformation of MnO2 has been considered in thin-layer MnO2/Al electrodes obtained by the mechanical rubbing of the active component in the aluminum matrix. The assessment of the lithium chemical diffusion coefficient DLi established in the redox reaction of MnO2 with lithium (in the range of 10-12 сm2/s) has been made in thin-layer composite MnO2 MWNTs/Al-electrodes at the current peak values (around 10-12 sm2/s) by the slow cyclic voltammetry.
Keywords: MnO2, lithium accumulator, multi-walled carbon nanotubes, discharge capacity, lithium chemical diffusion coefficient, thin-layer electrode.