Reuse of spent industrial graphite in batteries by green recycling and interphase functionalization

Abstract

With the widespread application of Li-ion batteries (LIBs) and the attendant appearance of large amounts of spent LIBs, recycling discarded graphite anodes is of great significance from the perspective of saving energy and resource sustainability. The conventional strategies for recycling graphite mainly include strong acid leaching and high-temperature calcination, which are environmentally hazardous or energy consuming. This work develops a green, economical and effective method to recover graphite from spent LIBs, which involves low-concentration organic citric acid leaching and a subsequent gravity separation process with a gelatin solution. This recycling route can increase the safety and operational feasibility of the industry, save energy, and thoroughly remove the metal-based and lightweight carbon-based impurities. Meanwhile, the graphite surface is functionalized with a gelatin layer, which works as an artificial interphase, suppresses electrolyte decomposition, and protects the graphite structure. The recycled graphite is further used as the cathode material in high-voltage (5.0 V) dual-ion batteries, exhibiting rapid charge/discharge capability and excellent cycling stability with a capacity retention of 87.9% after 4500 cycles. This work will be of great significance for the recycling of graphite and the sustainable development of energy storage technologies.