Flame‐Retardant Crosslinked Polymer Stabilizes Graphite–Silicon Composite Anode for Self‐Extinguishing Lithium‐Ion Batteries

The graphite-silicon composite (GSC) anode materials with high specific capacity and excellent conductivity hold intriguing promise for high-performance lithium-ion batteries (LIBs). However, commercializing GSC is hindered by its poor cyclability and safety issues. Here, a fire-resistant polymer crosslinked with ammonium polyphosphate (APP) and polyacrylic acid (PAA) to improve the electrochemical properties and enhance the safety of the GSC anode is designed. The crosslinked polymer not only forms a 3D network structure to strengthen the mechanical properties of the composite electrode but also uniformly covers the electrode surface to effectively minimize the side-reaction between electrodes and electrolyte, thereby improving its rate capacity and cycling stability. As a result, the GSC/PAA anode crosslinked with 10 wt% APP (GSC/10APP-PAA) delivers a high capacity of 315 mAh g(-1) at 0.5 C and stably operates for 1000 cycles with 0.03% capacity decay cycle(-1). More importantly, the peak heat release rate and the total heat release value of GSC/10APP-PAA anode are significantly depressed from 0.35 to 0.1 J s(-1), and from 1.6 to 0.6 J g(-1), respectively, thereby reducing the self-extinguishing time, which proves that the crosslinked polymer plays a fireproof role in the process of the thermal runaway of LIBs.