Ultra‐fast, low‐cost, and green regeneration of graphite anode using flash joule heating method

Abstract

Graphite is the state-of-the-art anode material for most commercial lithiumion batteries. Currently, graphite in the spent batteries is generally directly burned, which caused not only CO 2 emission but also a waste of precious carbon resources. In this study, we regenerate graphite in lithium-ion batteries at the end of life with excellent electrochemical properties using the fast, efficient, and green Flash Joule Heating method (FJH). Through our own developed equipment, under constant pressure and air atmosphere, graphite is rapidly regenerated in 0.1 s without pollutants emission. We perform a detailed analysis of graphite material before and after recovery by multiple means of characterization and find that the regenerated graphite displays electrochemical properties nearly the same as new graphite. FJH provides a large current for defect repair and crystal structure reconstruction in graphite, as well as allowing the SEI coating to be removed during ultra-fast annealing. The electric field guide the conductive agent and binder pyrolysis products to form conductive sheet graphene and curly graphene covering the graphite surface, making the recycled graphite even better than new commercial graphite in terms of electrical conductivity. Regenerated graphite has excellent multiplier performance and cycle performance (350 mAh g À1 at 1 C with a capacity retention of 99% after 500 cycles). At cost, we get recycled graphite that displays the same performance as new graphite, costing just 77 CNY per ton. This FJH method is not only universal for the regeneration of spent graphite generated by various devices but also enables multiple use-failure-regeneration steps of graphite, showing great potential for commercial applications.

Flash Recycling of Graphite Anodes

“…[ 22 ] Recent work has shown that the rapid electrothermal method can be applied to evaporate the impurities, including the binder and SEI, especially the lithium salts LiF and Li 2 CO 3 . [ 17 ] Their results were similar to the traditional high‐temperature treatment under inert atmosphere. The evaporation of the volatile compounds, and the expansion of the graphite structures were observed, leading to ≈40 times increasing of the surface area.…”

A recrystallization approach to repairing spent LiFePO4 black mass

“…As for the repaired LFP, the carbon residues were removed by LiNO 3 treatment (extra 1–2 wt%) and heavy liquid centrifuge separation 43 (>10 wt%), which can also be collected and recycled via other reported graphite recycling methods. 44–46 The carbon content in the final product was controlled within 5 wt%, as suggested by the TG curves in Fig. S1† (stoichiometrically, the added 8 wt% LiNO 3 can consume ∼2 wt% of zero-valent carbon in spent LFP at most).…”

Recycling of graphite anode from spent lithium‐ion batteries: Advances and perspectives

“…Some studies have revealed that recovered GA could be regenerated as anode materials for energy storage devices after some retreatments. [103][104][105][106] Low-cost regeneration of GA from spent LIBs is of great significance to solve the problem of waste graphite utilization and pollution. Comparing with the fresh graphite, the directly recycled GA (with coating, SEI layer and other Impurities) exhibits lower initial discharge capacity, which are 354.2 and 298.7 mAh/g respectively.…”

“…Some studies have revealed that recovered GA could be regenerated as anode materials for energy storage devices after some retreatments 103–106 . Low‐cost regeneration of GA from spent LIBs is of great significance to solve the problem of waste graphite utilization and pollution.…”