Silicon (Si) is one of the most promising anode materials for high-capacity lithium-ion batteries. However, its drastic volume changes during cycling lead to fast capacity decay. Binders play an important role in maintaining the structural integrity of electrodes. This paper proposes a three-dimensional binder network, which synthesized by weaving Ni 2+ anchored soft gellan gum chains with linear rigid polyvinyl alcohol chains. Benefiting from the soft-rigid synergy and self-recovery ability of the obtained binder, the Si anode delivers over 1500 mAh g −1 after 500 cycles at 2.1 A g −1 , and post-analysis proofs that this binder can buffer the volume changes of Si particles and retain the overall stability of the electrode. In addition, the optimized Si anode still have a high capacity retention of ca. 50% even at 84 A g −1 , because the binder network can provide uniform Li + flux and more Li + transport channels for the electrode.
Xingyi Shi,Qingwei Sun,Bismark Boateng,Yinghua Niu,Yidong Han,Weiqiang Lv,Weidong He
The safety of lithium ion batteries is correlated closely to the mechanical property and thermal stability of separators. The polymer/ceramic particle composite separators are widely investigated for quasi-solid gel separators of lithium ion batteries, but the nonuniform dispersion of ceramic particles limits their performance. In this study, ball-milled Al-doped Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 suspension is incorporated into poly (vinylidene fluoride- co -hexafluoropropylene) gel to prepare a highly uniform quasi-solid composite separator. The results show that adding only 4.29 wt% Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 into PVDF-HFP increases ductility by three times and the mechanical strength by 38% as compared with pure PVDF-HFP separator. Batteries with the composite separator show significantly improved cyclic stability and rate performance at both room temperature and temperatures up to 80 °C. In particular, the composite separator promotes homogenous Li + flux through the separator and suppresses Li dendrite growth in Li-metal based batteries.
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