Studies of Lithium Intercalation into Carbons Using Nonaqueous Electrochemical Cells

Abstract

Li/graphite and Li/petroleum coke cells using a 1M LiAsF6 in a 50:50 mixture of propylene carbonate (PC) and ethylene carbonate (EC) electrolyte exhibit irreversible reactions only on the first discharge. These irreversible reactions are associated with electrolyte decomposition and cause the formation of a passivating film or solid electrolyte interphase on the surface of the carbon. The amount of electrolyte decomposition is proportional to the specific surface area of the carbon electrode. When all the available surface area is coated with the film of decomposition products, further decomposition reactions stop. In subsequent cycles, these cells exhibit excellent reversibility and can be cycled without capacity loss.

Characteristics of a Graphene Nanoplatelet Anode in Advanced Lithium‐Ion Batteries Using Ionic Liquid Added by a Carbonate Electrolyte

“…The signifi cant irreversible capacity observed during the fi rst cycle is commonly attributed to side reactions induced by functional groups, oxygen atoms, hydrogen atoms, and eventual impurities at the carbon electrode surface [37][38][39] and to electrolyte decomposition with consequent SEI formation. [ 40 ] We already demonstrated in previous papers that irreversible capacity of the graphene-based materials may be effi ciently reduced by direct treatment with lithium metal (see also Experimental Section), thus making the electrodes suitable for application in effi cient lithium-ion battery. [ 18,32 ] Despite the highly defective materials previously studied have greatly promoted the Li-uptake within the graphene, i.e., leading to a capacity approaching the theoretical value of 744 mAh g −1 , they were, however, characterized by a very large irreversible capacity during the fi rst cycles.…”

Design and Materialization of Ionic Liquids Based on an Understanding of Their Fundamental Properties

“…117 Electrochemical Li + intercalation into graphite electrodes is solvent-selective, and the formation of a favorable solid electrolyte interphase (SEI) that enables desolvation of Li + at the interface and conduction Li + in the layer is considered to be essential. 125 121 The success of the electrochemical intercalation/deintercalation can be correlated with the activity the Li + -solvating free solvent, and very low activity of such solvent makes electrochemical intercalation/deintercalation possible. 122 …”

Performance study of commercial LiCoO2 and spinel-based Li-ion cells

“…This capacity fade is caused by various mechanisms, which depend on the electrode materials and also on the protocol adopted to charge the cell. Capacity fade in Li-ion cells can be attributed to unwanted side reactions that occur during overcharge or discharge, which causes electrolyte decomposition, passive film formation, active material dissolution and other phenomena [1][2][3][4][5][6][7][8][9][10].…”

“…Li deposition will take place in cells with excess cyclable Li due to either higher than desired initial mass ratio or lower than expected Li losses during the formation period [1]. According to Dahn and co-workers [2] and Aurbach and co-workers [3], the Li metal which is deposited on the negative electrode reacts quickly with the solvent or salt molecules in the vicinity giving Li 2 CO 3 , LiF or other products. The products formed may block the pores, leading to a loss of rate capability as well as capacity losses.…”