Comprehensive Technology for Recycling and Regenerating Materials from Spent Lithium Iron Phosphate Battery.

The lithium iron phosphate (LFP) battery has been widely used in electric vehicles and energy storage for its good cyclicity, high level of safety, and low cost. The massive application of LFP battery generates a large number of spent batteries. Recycling and regenerating materials from spent LFP batteries has been of great concern because it can significantly recover valuable metals and protect the environment. This paper aims to critically assess the latest technical information available on the echelon utilization and recycling of spent LFP batteries. First, it focuses on the progress of disassembly, evaluation and detection, regrouping, and application in echelon utilization. Then, the recycling technologies, including pretreatment, direct repair, and material regeneration, of spent LFPs are summarized. Finally, the paper proposes some challenges in the echelon utilization and recycling of spent LFP batteries, and concludes with recommendations for an intelligent, refined, and clean LFP battery circulation system that are required to ensure the sustainable development of spent LFP battery recycling.

Lithium recovery and solvent reuse from electrolyte of spent lithium-ion battery.

Great progresses have been made in recovering valuable metals or regenerating materials from spent lithium-ion batteries (LIBs), but how to treat the spent electrolyte and recover its valuable components economically are still a bottleneck. In this study, the volatile organic solvents (dimethyl carbonate (DMC) and diethyl carbonate (DEC)) in spent electrolyte were recycled through vacuum distillation based on thermodynamic analysis and reused for LIBs. The recovery efficiencies of DMC and DEC reach almost 100% and 79.40%, respectively, under the distillation temperature of 130 °C for 120 min. The prepared electrolyte by recovered DMC and DEC shows high discharge capacity and good cycle performance (discharge capacity retention is over 99% after 400 cycles at 1C) by Li/graphite battery. Moreover, lithium left in non-volatile components (ethylene carbonate (EC)) was recovered as lithium carbonate (purity is 92.45%) with a recovery efficiency of 86.93%. The proposed process sheds light on the comprehensive recycling of electrolyte from spent LIBs.

Solvent extraction for recycling of spent lithium-ion batteries.

Up to now, solvent extraction not only recycle valuable metals (i.e., Ni, Co, Mn and Li) from the leach liquor of spent cathode materials, but also apply to treat spent electrolyte. This paper summarizes the development of solvent extraction in the field of recycling spent lithium-ion batteries (LIBs) from the aspects of principle, technology and industrialization. Meanwhile, the paper also comments on the challenges and opportunities for the solvent extraction facing in the recycling of spent LIBs.

Stepwise recycling of valuable metals from Ni-rich cathode material of spent lithium-ion batteries.

A novel and efficient approach for stepwise recycling of valuable metals from Ni-rich cathode material is developed. First, the spent cathode materials are leached by H2SO4 + H2O2 solution. The leaching efficiencies of lithium, nickel, manganese and cobalt reach almost 100%, 100%, 94% and 100%, respectively, under the conditions of 2 M sulfuric acid, 0.97 M hydrogen peroxide, 10 ml·g-1 liquid-solid ratio, 30 min and 80 °C. Then, manganese and cobalt are co-extracted from the leaching liquor with PC88A, while almost 99% nickel and 100% lithium remain in the raffinate followed by being separated from each other by solvent extraction with neodecanoic acid (Versatic 10). The results show that 98% manganese and over 90% cobalt are co-extracted at pH = 5, 30 vol% PC88A and volume ratio of oil to water (O:A) = 2:1, while 100% nickel is separated from lithium under the optimum extraction conditions of initial pH = 4, O:A = 1:3 and 30 vol% Versatic 10. Finally, cobalt and manganese in the strip liquor of co-extraction are separated by selective precipitation method. Over 90% manganese is separated from cobalt under the conditions of pH = 0.5, 0.076 M KMnO4, 80 °C and 60 min.

A process for combination of recycling lithium and regenerating graphite from spent lithium-ion battery.

Recycling lithium and graphite from spent lithium-ion battery plays a significant role in mitigation of lithium resources shortage, comprehensive utilization of spent anode graphite and environmental protection. In this study, spent graphite was firstly collected by a two-stage calcination. Secondly, under the optimal conditions of 1.5 M HCI, 60 min and solid-liquid ratio (S/L) of 100 g·L-1, the collected graphite suffers simple acid leaching to make almost 100% lithium, copper and aluminum in it into leach liquor. Thirdly, 99.9% aluminum and 99.9% copper were removed from leach liquor by adjusting pH first to 7 and then to 9, and thenthe lithium was recovered by adding sodium carbonate in leach liquor to form lithium carbonate with high purity (>99%). The regenerated graphite is found to have high initial specific capacity at the rate of 37.2 mA·g-1 (591 mAh·g-1), 74.4 mA·g-1 (510 mAh·g-1) and 186 mA·g-1 (335 mAh·g-1), and with the high retention ratio of 97.9% after 100 cycles, it also displays excellent cycle performance at high rate of 372 mA·g-1. By this process, copper and lithium can be recovered and graphite can be regenerated, serving as a sustainable approach for the comprehensive utilization of anode material from spent lithium-ion battery.

Optimization and Evaluation of Ventilation Mode in Marine Data Center Based on AHP-Entropy Weight.

The ventilation mode affects the cooling efficiency of the air conditioners significantly in marine data centers. Three different ventilation modes, namely, underfloor ventilation, overhead ventilation, side ventilation, are numerically investigated for a typical marine data center. Four independent parameters, including temperature, velocity, air age, and uniformity index, are applied to evaluate the performances of the three ventilation modes. Further, the analytic hierarchy process (AHP) entropy weight model is established and further analysis is conducted to find the optimal ventilation mode of the marine data center. The results indicate that the underfloor ventilation mode has the best performance in the airflow patterns and temperature distribution evaluation projects, with the highest scores of 91.84 and 90.60. If low energy consumption is required, it is recommended to select the overhead ventilation mode with a maximum score of 93.50. The current evaluation results agree fairly well with the three dimensional simulation results, which further proves that the AHP entropy weight method is reasonable and has a high adaptability for the evaluation of air conditioning ventilation modes.