Sacrificial Co-solvent Electrolyte to Construct a Stable Solid Electrolyte Interphase in Lithium-Oxygen Batteries.

Lithium-oxygen batteries are vital devices for electrochemical energy storage. The electrolyte is a crucial factor for improving battery performance. The high reactivity of lithium metal induces side reactions with organic electrolytes, thus leading to an unstable interface between the anode and electrolyte and poor performance of batteries. In this work, to compensate for the above shortcomings, 1-methylimidazole (MeIm) is introduced to the tetraethylene glycol dimethyl ether (TEGDME) electrolyte to form the TEGDME/MeIm co-solvent electrolyte. Because of the high donor number value of MeIm, the solution-based pathway of discharge products can be triggered. Compared with the single TEGDME electrolyte, the discharge capacity with the TEGDME/MeIm co-solvent electrolyte is increased by more than 2 times. Moreover, the TEGDME/MeIm co-solvent electrolyte can promote the dissociation of Li salt due to the high dielectric constant of MeIm and thus make up for the shortcomings of TEGDME. In addition, due to the lower energy than the lowest unoccupied molecular orbital (LUMO) level of TEGDME, MeIm is decomposed preferentially, and a dense solid electrolyte interphase (SEI) layer is constructed. Then, the decomposition of TEGDME is suppressed. Therefore, the cycle performance of the battery with the TEGDME/MeIm co-solvent electrolyte is 18 times compared to that with the single TEGDME electrolyte.

A Surface Coordination Interphase Stabilizes a Solid-State Battery.

Solid-state electrolytes (SSEs) show potential in addressing the safety issues of liquid batteries, but the poor interface contact between them and the electrodes hinders practical applications. Here, coordination chemistry of nitrile groups based on succinonitrile (SCN) and polyacrylonitrile (PAN) is studied on the surface of Li6.4 La3 Zr1.4 Ta0.6 O12 (LLZTO) SSE to build the chemical bonded electrolyte/electrode interfaces. The coordination of the nitrile group and LLZTO is clarified. A deformable PAN-modifying SCN electrolyte (PSE) interphase with stable ionic conductivity (10-4  S cm-1 ) and high lithium-ion transference number (0.66) is fabricated on the surface of LLZTO electrolyte based on the coordination competition of nitrile groups. Once applied to SSBs, it endows low interface resistance and strong bonding for the electrolyte/electrode interfaces so that the initial Coulomb efficiency reaches 95.6 % and the capacity remains 99 % after 250 cycles at 25 °C.

Bifunctional 1-Boc-3-Iodoazetidine Enhancing Lithium Anode Stability and Rechargeability of Lithium-Oxygen Batteries.

Lithium anode protection is an effective strategy to prohibit the continuous loss of redox mediators (RMs) resulting from the unfavorable "shuttle effect" in lithium-oxygen batteries. In this work, an in situ Li anode protection method is designed by utilizing an organic compound, 1-Boc-3-iodoazetidine (BIA), as both a RM and an additive, to form a lithium anode protective layer. The reaction between Li metal and BIA can form lithium iodide (LiI) and lithium-based organometallic. LiI can effectively reduce the charging overpotential. Meanwhile, the in situ-formed anode protection layer (lithium-based organometallic) can not only effectively prevent RMs from being reduced by the lithium metal, but also inhibit the growth of lithium dendrites. As a result, the lithium-oxygen battery with BIA shows a long cycle life of 260 cycles with a notably reduced charging potential. In particular, the battery with BIA achieves an excellent lifespan of 160 cycles at a large current density of 2000 mA g-1.