Colloid Electrolyte Containing LiP Nanoparticles for Highly Stable 4.7 V Lithium Metal Batteries.

Lithium metal batteries (LMBs) with LiNiCoMnO (NCM811) cathodes have garnered significant interest as next-generation energy storage devices due to their high energy density. However, the instability of their electrode/electrolyte interfaces in regular carbonate electrolytes (RCEs) results in a rapid capacity decay. To address this, a colloid electrolyte consisting of LiP nanoparticles uniformly dispersed in the RCE is developed by a one-step synthesis. This design concurrently creates stable cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI) on both electrode surfaces. The cathode interface derived from this colloid electrolyte significantly facilitates the decomposition of Li salts (LiPF and LiDFOB) on the cathode surface by weakening the P-F and B-F bonds. This in situ formed P/LiF-rich CEI effectively protects the NCM811 cathode from side reactions. Furthermore, the LiP embedded in the SEI optimizes and homogenizes the Li-ion transport, enabling dendrite-free Li deposition. Compared to the RCE, the designed colloid electrolyte enables robust cathode and anode interfaces in NCM811||Li full cells, minimizing gas and dendrite formation, and delivering a superior capacity retention of 82% over 120 cycles at a 4.7 V cutoff voltage. This approach offers different insights into electrolyte regulation and explores alternative electrolyte shapes and formulations.