Oxidative Pyrolysis of Si/Polyacrylonitrile Composites as an Unconventional Approach to Fabricate High Performance Lithium Ion Battery Negative Electrodes

Abstract

High performance Si/polyacrylonitrile (PAN) composite negative electrodes are fabricated by a robust process of oxidative pyrolysis at a temperature between 250 and 400°C. Multiple techniques are employed to investigate the structural, chemical, and mechanical properties of the Si/PAN composite electrodes before and after oxidative pyrolysis. With increasing temperature, oxidation, dehydration, aromatization, and intermolecular crosslinking take place in PAN, resulting in a stable cyclized structure which functions as both a binder and a conductive agent in the Si/PAN composite electrodes. Meanwhile, PAN reacts with oxygen, forming volatile products and producing progressively porous Si/PAN composites with increasing temperature. With a Si mass loading of 1 mg/cm 2 , a discharge capacity of 1555 mAh/g at the 100 th cycle is observed from the 400°C treated Si/PAN composite electrode when cycled at a rate of C/3. This 400°C treated electrode also shows good rate capability. It exhibits a specific discharge capacity of ∼500 mAh/g at 3C compared to the nearly zero capacity for those treated at lower temperatures. This facile method of synthesizing Si-based composite negative electrodes can potentially be applied to other Si/polymer systems for further increasing the power/energy density of lithium ion batteries.

Multiscale Understanding of Covalently Fixed Sulfur–Polyacrylonitrile Composite as Advanced Cathode for Metal–Sulfur Batteries

“…Silicon (Si) or silicon (SiO 2 ) is a popular electrode material for LIBs due to its high theoretical capacity of 3579 mAh g −1[ 137 , 138 , 139 , 140 ] or 4200 mAh g −1 . [ 141 ] Further, safety performance and suitable operating potential make it promising candidate for practical batter application.…”

“…Furthermore, the pPAN/SeS 2 prepared by applying a high voltage (17 kV) exhibited a discharge capacity of 871 mAh g −1 at 4 A g −1 , which remained at 633 mAh g −1 after 2000 cycles maintaining a very low capacity decay rate (0.014% per cycle) (Figure 13g). [136] Silicon (Si) or silicon (SiO 2 ) is a popular electrode material for LIBs due to its high theoretical capacity of 3579 mAh g −1 [137][138][139][140] or 4200 mAh g −1 . [141] Further, safety performance and suitable operating potential make it promising candidate for practical batter application.…”

Magnetic Force Dilatometry of Silicon-NMC622 Lithium-Ion Coin Cells: The Effects of Binder, Capacity Ratio, and Electrolyte Selection

“…41 Another direction that has been explored is the use of carbonized binders, which have improved electrical conductivity and helped prolong cycle life in silicon electrodes. [42][43][44] There are few reports on the expansion of these electrodes, but Mukhan et al have reported that silicon electrodes containing pyrolyzed poly ether imide (PEI) binder showed significantly less expansion in the first two cycles than electrodes with a conventional polyvinylidene difluoride (PVDF) binder, which was attributed to the superior binder-silicon bonding between silicon and PEI than with PVDF. 45 In addition, electrode reversibility was improved with the pyrolyzed PEI binder, compared to electrodes made with PVDF or sodium-carboxymethyl cellulose binders.…”