Volumetric Stress Managements on Silicon Anode of Lithium-Ion Batteries by a Self-Adaptable Binder

The intrinsic volume changes (about 300%) of Si anode during the lithiation/delithiation leads to the serious degradation of battery performance despite of theoretical capacity of 3579 mAh g-1 of Si. Herein, a three-dimensional (3D) conductive polymer binder with adjustable crosslinking density has been designed by employing citric acid (CA) as a crosslinker between the carboxymethyl cellulose (CMC) and the poly(3,4-ethylenedioxythiophene) poly-(styrene-4-sulfonate) (PEDOT:PSS) to stabilize Si anode. By adjusting the crosslinking density, the binder can achieve a balance between rigidity and flexibility to adapt the volume expansion upon lithiation and reversible volume recovery after delithiation of Si. Therefore, Si/CMC-CA-PEDOT:PSS (Si/CCP) electrode demonstrates an excellent performance with high capacities of 2792.3 mAh g-1 at 0.5 A g-1 and a high area capacity above 2.6 mAh cm-2 under Si loading of 1.38 mg cm-2. The full cell Si/CCP paired with Li(Ni0.8Co0.1Mn0.1)O2 cathode discharges a capacity of 199.0 mAh g-1 with 84.3% ICE at 0.1 C and the capacity retention of 95.6% after 100 cycles. This work validates the effectiveness of 3D polymer binder and provides new insights to boost the performance of Si anode.