Capacity degradation mechanism and improvement actions for 4 V-class all-solid-state lithium-metal polymer batteries

Owing to high safety and considerable energy density , rechargeable all-solid-state lithium-metal polymer batteries (ASSLPBs) with organic-inorganic composite solid-state electrolytes (CSSEs) have been recognized as one of the most promising battery systems. However, 4 V or above-class ASSLPBs still suffer serious capacity degradation arising from the complex interface issues between the electrode and electrolyte. Herein, for the first time, we find the oxidation decomposition of TFSI - anion and further interaction with PEO polymer matrix in the LiNi 0.8 Co 0.1 Mn 0.1 LiO 2 (NCM811)/CSSEs (PEO-LiTFSI-LAGP)/Li cell, which cause continuous damage to the interfacial stability and persistent capacity degradation. Increasing the ratio of LAGP filler in CSSEs membrane and employing PEO-LiBOB electrolyte in composite cathode were demonstrated effective. As a consequence, the ASSLPBs show high reversibility, and high capacity retention up to 88% (3.0–4.2 V) and 78% (3.0–4.3 V) after 100 cycles with the charge/discharge current density of 30 mA g −1 (35 °C). The understanding on capacity degradation mechanism, along with the positive improvement strategies validly boosts the development and promising application of 4 V-class ASSLPBs.