A Temperature-Controlled\nChemoswitching Aqueous Binder\nand In Situ Binding Strategy for Stabilizing SiO<sub><i>x</i></sub> Anodes of Lithium-Ion Batteries

Silicon oxide (SiO<sub><i>x</i></sub>), as\nan anode material\nof lithium-ion batteries (LIBs), can discharge higher specific energy\nthan graphite, but accommodating the structural damage caused by the\nstress change of lithiation/delithiation remains a challenge. In this\nwork, poly(acrylic acid) (PAA) and polyethylenimine (PEI) have been\nused as the main body, where PAA as the initiator triggers the cross-linking\nreaction with PEI (cross-linker). While ammonia as the chemical switching\nagent (NH<sub>3</sub>·H<sub>2</sub>O) and carboxymethyl cellulose\n(CMC, thickener) served as the chemical switch for the whole cross-linking\nprocess, a temperature-controlled chemical switching aqueous binder\nhas been developed for stabilizing SiO<sub><i>x</i></sub> anodes for lithium batteries. The SiO<sub><i>x</i></sub> anode with the temperature-controlled chemoswitching aqueous binder\ngives a reversible capacity of 1310 mAh g<sup>–1</sup> (81%\ncapacity retention) after 400 cycles at 0.5 C. After 300 cycles at\n2 C (25 °C) and 1 C (45 °C), the specific capacities are\n1060 and 1039 mAh g<sup>–1</sup>, respectively. This binding\nmethod can form strong intermolecular forces on the SiO<sub><i>x</i></sub> surface and reduce the energy of lithium-ion diffusion.\nQuantitative simulations show that the energy to be overcome for lithium\nion transfer trajectories is small in PEI@PAA. In addition, it avoids\nthe premature cross-linking of binder precursors, ultimately improves\nthe performance of the SiO<sub><i>x</i></sub> anode, indicating\npromising application prospects.