Ameliorating Interfacial Issues of LiNi 0.5 Co 0.2 Mn 0.3 O 2 /Poly(propylene carbonate) by Introducing Graphene Interlayer for All‐Solid‐State Lithium Batteries

Interfacial side reaction mechanism between poly(propylene carbonate) solid polymer electrolyte (PPC-SPE) and LiNi0.5Co0.2Mn0.3O2 cathode (c-NCM) is investigated. Ni3+ and Co4+ species generated by electrochemical oxidization process can decompose poly(propylene carbonate) to aldehyde. To address this interface issue, a graphene interlayer is introduced to the LiNi0.5Co0.2Mn0.3O2 cathode surface via a facile method to improve cycle stability, rate capability and interfacial resistance. After 50 cycles at 0.3 C, the capacity retention of G@c-NCM is 97.9 % and the resistance is less than 20 Ω, the improved electrochemical properties can be attributed to the graphene interlayer slows the side reaction, facilitates interfacial charge-transfer process and stabilizes the cathode structure. These results demonstrate that modifying LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode surface with graphene interlayer is conducive to enhance the electrochemical performance of all-solid-state lithium batteries.