Universal strategy of capacity-compensation via electrolyte for Li-ion batteries

Abstract

The initial irreversible capacity loss (ICL) during the first charging process greatly reduces the affordable energy and power densities of commercial Li-ion batteries (LIBs). Though various solid-phase prelithiation additives have been developed, they can hardly be adapted to the existing electrode production lines. Herein, we elucidate that the root cause of ICL is electron loss, therefore, the most sustainable and economical capacity-compensation method is to compensate for electrons rather than conventional prelithiation. Accordingly, we propose a universal capacity-compensation strategy via electrolyte, and establish general guiding principles for developing soluble capacity-compensation reagents. As a proof of concept, lithium polyphosphides (LixPPs) was synthesized and evaluated. LixPPs feature desirable solubility in various commercial electrolytes and undergo preferential oxidation at the cathode side, thereby not only compensating for ICL but also contributing to the construction of a stable cathode-electrolyte interphase (CEI). The feasibility of this capacity-compensation electrolyte has been successfully validated in multiple mainstream battery systems, including NCM811||graphite, LiFePO4||graphite, and LiCoO2||graphite full cells, highlighting both its great adaptability to the existing battery manufacturing processes and its potential to enhance the energy density of LIBs and beyond.