Regeneration of LiFePO₄ from spent lithium-ion batteries via a facile process featuring acid leaching and hydrothermal synthesis

Abstract

LiFePO4 has been regenerated from spent lithium-ion batteries via a facile process involving acid leaching and hydrothermal synthesis.

Enabling the sustainable recycling of LiFePO4 from spent lithium-ion batteries

“…The FePO 4 phase occupies a portion of the stable region in an appropriate pH from −2.82 to 8.15, in which LiFePO 4 can be converted into Li + and FePO 4 in the presence of an oxidant. 34,35 Unexpectedly, the pH changes of the solution with the oxidation leaching time varies from 3.93 to 8.10, which occurs in this stable domain of FePO 4 , and also contributes to the oxidation reaction at 50 °C (Fig. 3b).…”

“…23 Through the optimum leaching parameters, the external diffusion controlled reaction, internal diffusion controlled reaction and chemical reaction controlled reaction are assumed as the typical ratecontrolling steps and analyzed by kinetics data fitting (Table 1). 33,34 At 50 °C, it was discovered that the correlation coefficient R 2 was as high as 0.98 when the internal diffusion and chemical reaction were considered the rate-controlling steps, while the value of R 2 was 0.96 for external diffusion (Fig. 2b).…”

“…When internal diffusion was the ratecontrol step, the activation energy of Li was determined to be 15.64 kJ mol −1 , less than 20 kJ mol −1 , from which the leaching reaction belonging to the ion diffusion control could be inferred. 34 Therefore, the oxidation extent of LiFePO 4 was affected by the hydrogen peroxide content.…”

“…8). 34,37 Impressively, hydrogen peroxide as a common oxidant is a green reagent. It decomposes to produce water and oxygen without introducing other impurities, which has been extensively applied for industrial processes.…”

A Review on Regenerating Materials from Spent Lithium-Ion Batteries

“…The discharge capacity of regenerated LiFePO 4 was 136 mAh/g at 0.1 C, and the retention ratio reached 98.6% at 1 C after 300 cycles ( Figure 5 b). It was implied that the material is comparable to the commercial LiFePO 4 cathode material [ 33 ]. Yang et al used H 2 SO 4 and H 2 O 2 to leach valuable metals from spent ternary LIBs and then adjusted the molar ratio of metal to regenerate the precursors Ni 1/3 Co 1/3 Mn1 /3 (OH) 2 by co-precipitation.…”