Title：Ultra-efficient polymer binder for silicon anode in high-capacity lithium-ion batteries
Authors：Shilun Gao, Feiyuan Sun, Alexander Brady, Yiyang Pan, Andrew Erwin, Dandan Yang, Vladimir Tsukruk, Andrew G. Stack, Tomonori Saito, Huabin Yang*, Peng-Fei Cao**
Publication：Nano Energy 73 (2020) 104804
As a highly promising anode material for high-capacity lithium-ion batteries (LIBs),the low electronic conductivity and large volume variation of silicon (Si) make the slurry-coating Si based electrode requiring high content of “inert” materials and suffering rapid capacity fading. Herein, a polyimine, synthesized via one-step condensation reaction, has been demonstrated as an ultra-efficient polymer binder that can resolve the above issues. The polyimine binder containing Si electrode delivers superior electrochemical performance: a delithiation specific capacity of 804.4 mAh g-1 with capacity retention of 82.4% after 1000 cyclesat the current density of 2 A g-1. The high efficiency of polyimine binder for Si electrode has also been demonstrated with ultrahigh weight ratio of “active” material to “inert” material (RA/I). The electrode with 95 wt% of Si (95Si/Polyimine, RA/I=19) reveals a reversible delithiation capacity of 2114 mAh g-1(capacity retention ~ 80.4%) over 200 cycles at the current density of 400 mA g-1. Even at the high current density of 2 A g-1, a delithiation capacity of 1087.8 mAh g-1 after 500 cycles can be obtained. Molecular simulations and atomic force microscopy (AFM) indentation are utilized to investigate the ultra-efficiency of polyimine binder. With simple manufacturing process and ultra-efficient binder performance, the designed polyimine binder will be definitely meaningful in achieving low-cost and high-capacity LIBs with prolonged cycle life.