Additives Capable\nof Stably Supplying Anions/Cations\nfor Homogeneous Lithium Deposition/Stripping

One of the important factors leading to lithium dendrites\nis a\nslow lithium-ion mass transport and imbalanced distribution of the\nLi<sup>+</sup> concentration and nuclei sites on the anode surface.\nTo achieve uniform lithium deposition during the charge and discharge\nprocess, we introduce a homemade new copolymer (with the quaternary\nammonium group N<sub>3</sub>R<sup>+</sup>I<sup>–</sup> on its\nside chain as the main functional group), named P35, as a functional\nelectrolyte additive to regulate the lithium deposition. Theoretical\ncalculations show that under the strong coordinating interaction between\nI<sup>–</sup> and N<sub>3</sub>R<sup>+</sup>, P35 preferentially\nadsorbs onto the lithium foil surface, effectively countering the\nadsorption of lithium salt anions such as PF<sub>6</sub><sup>–</sup>. Moreover, the positive charge carried by the quaternary ammonium\nsalt group of P35 could interact with PF<sub>6</sub><sup>–</sup> to limit their mobility. Consequently, the dipole interaction on\nlithium ions is diminished, leading to an enhancement in the transport\nrate and a decrease in the concentration gradient of lithium ions.\nFurthermore, a more efficient SEI was formed due to the dual charges\nelectrostatic shield formed by N<sub>3</sub>R<sup>+</sup>I<sup>–</sup>. Li–Li symmetric cells and Li–LiFePO<sub>4</sub> full\ncells assembled with electrolytes with P35 exhibit better rate performance,\nsmaller polarization, and smoother deposition morphology in comparison\nto the cells without the P35 additive.