Enhancement of electrochemical performance of tin-based anode in lithium ion batteries by polyimide containing amino benzoquinone

To study the effect of different polymer binders on the electrochemical performance of tin electrodes for rechargeable lithium-ion batteries, poly(vinylidene fluoride) (PVDF), conventional polyimide (PI-OB), and synthesized polyimide containing amino benzoquinone (PI-AQOB) were used as the polymer binders for electrodes consisting of commercial powdered Sn particles and Super P. PI-AQOB was converted from polyamic acid (PA-AQOB) synthesized from 2,5-bis(4,4'-oxydianiline)-1,4-benzoquinone (AQODA) and 4,4'-biphthalic dianhydride (BPDA) by condensation polymerization and characterized by Fourier-transform infrared analysis. Compared to the electrode employing the traditional PVDF binder, those with the PI-AQOB binder exhibited significantly enhanced electrochemical performance in terms of rate capability, specific capacity, and cycling behavior. PI-AQOB provided a high initial lithiation capacity of 1529 mAh/g at a current density of 50 mA/g. After 50 cycles, the PI-AQOB electrode maintained a higher specific capacity of 332 mAh/g than the Sn/PVDF electrode (only 65 mAh/g at a current density of 200 mA/g). Furthermore, the Sn/PI-AQOB electrode exhibited good volume restoration compared to the electrodes with Sn/PVDF and Sn/PI, as indicated by scanning electron microscopic analysis. The PI-AQOB binder increased the mechanical and adhesive strength of the electrode by suppressing pulverization of the Sn anode during expansion/contraction of Sn particles in the lithiation/delithiation process.