Pyromellitic acid induced stable lithium ion batteries based on recycled silicon flakes

Abstract

State-of-the-art capacity and stability of the silicon (Si) anode already meet the requirments of lithium ion batteries (LIBs). However, the high-cost techniques hinder its practical applications. Herein, we developed a facile strategy to greatly enhance the electrochemical performance of the recycled Si material worked with commercial carboxymethyl cellulose : styrene butadiene rubber and conductive material. In that, small amount of pyromellitic acid (PA) with multi-carboxylic groups as the additive played a key role by passivating the Si surface, forming 3-dimensional crosslink network structure and anchoring the electrode onto Cu current collector. Thus, the side-reactions between Si-electrolyte and volume expansion during charge-discharge process were effectively suppressed. Moreover, the addition of PA also increased the porosity of the electrode by altering the compositions distribution, and the introduction of Ni2+ as the complexant can further enhance these effects. As a matter of fact, the Si-anode exhibited outstanding electrochemical performance with an initial charge capacity of 2325.0 mAh g−1 and a charge capacity retention of 1268.8 mAh g−1 after 500 cycles at a current density of 1000 mA g−1, corresponding to an average decay rate of 0.091% per cycle. Additionally, a capacity of 1079.7 mAh g−1 can be still achieved at a high current density up to 10,000 mA g−1. The performance surpassed that reported in the literatures using similar Si-flakes and are comparable to that using nanoSi and complicated technique. Overall, our work enabled a simple and cost-effective way for the practical application of Si materials.