Effective regeneration of scrapped LiFePO4 material from spent lithium-ion batteries

A sustainable strategy for spent Li-ion battery regeneration: microwave-hydrothermal relithiation complemented with anode-revived graphene to construct a LiFePO4/MWrGO cathode material

“…After charging and discharging at different rates, the cathode is restored to its original state at 0.2C. A comparison of the rate performances of the LFP/MWrGO-5% cathode with previously reported hydrothermally regenerated LFP materials 26,27 shows that the former has a significantly better rate performance due to the improved conducting mode and unique hierarchical structure attributed to MWrGO, according to Raman spectroscopy and SEM.…”

“…Defect repair and replenishment of Li ions, through techniques, such as the electrochemical method, 21 solid-state calcination, [22][23][24][25] or the hydrothermal method, 26,27 are key to the direct regeneration of LFP. Of these techniques, the electrochemical method is unsuitable for real applications because it requires relithiation of the spent LFP by a Li anode in a half-cell, and therefore cannot be directly used.…”

“…The use of graphene to construct a hierarchical composite structure can help to ameliorate the electronic conductivity, Li-ion diffusion, and performance at high rates. Though recycling techniques for spent LFP cathodes including lithium salt extraction, 5,8,11,12,26,34 lithium replenishment, 14,22,24,27 and modication by carbon coating 22 have been reported in the literature, reports on directly regenerating LFP cathodes complemented with anode-revived graphene doping are scarce, which has motivated this study.…”

“…As shown in Fig. 8, compared with the conventional hydrothermal method, 26,27 owing to the novel microwave-material interaction (Fig. S2 †), MWHT treatment not only drastically reduces the processing time but also improves the electrochemical performance and cycle stability.…”

Direct Regeneration of Spent Lithium Iron Phosphate via a Low-Temperature Molten Salt Process Coupled with a Reductive Environment

“…The spent LFP cathode is typically featured with partial loss of active lithium and iron occupation at the lithium site over repeated cycles. − Solid-state roasting , and hydrothermal treatment , have been widely employed to compensate for the lost lithium in the LFP cathode and to restore the crystallographic structure. The solid-state roasting method is scalable and practically relevant, which requires high-temperature annealing of the spent LFP cathode assisted with the lithium source and reducing agent to regenerate the LFP structure .…”