For environmental and sustainability reasons, spent Li-ion batteries must be recovered and recycled so that the full promise of an electrified future is realized. Li-ion battery recycling streams pose a serious challenge to all existing recycling technologies because of their unknown and diverse chemistry. In the work described in this paper, four representative recycling streams were used to demonstrate the flexibility of the recycling process developed at Worcester Polytechnic Institute (WPI) to accommodate a variable feed and to generate consistent quality cathode material, LiNi1/3Mn1/3Co1/3O2 (NMC111). Ni1/3Mn1/3CO1/3(OH)2 precursors derived from four recycling streams were produced by a hydroxide coprecipitation method in a continuous stirred tank reactor. It took 2 days for the coprecipitation reaction to reach steady state. A possible evolution of the precursor particles up to the steady state was proposed. Both the precursors and the cathodes from these four different recycling streams exhibit similar morphology, particle size distribution, and tap density. Moreover, these recovered cathode materials display similar electrochemical properties. Surprisingly, these recovered NMC111s have better rate capability than a commercial NMC111 prepared from virgin materials. The different chemical compositions of the incoming recycling streams were shown to have little observed effect on the recovered precursor and resultant cathode material generated by the WPI-developed recycling process with advantages including no sorting, low temperature, and high quality recovered battery materials. Therefore, the WPI-developed process applies to different spent Li-ion battery waste streams and is, therefore, general.

The occurrence of mental fatigue when users stare at stimuli is a critical problem in the implementation of steady-state visual evoked potential (SSVEP)-based visual acuity assessment, which may weaken the SSVEP amplitude and signal-to-noise ratio (SNR) and subsequently affect the results of visual acuity assessment. This study aimed to explore the anti-fatigue performance of six stimulus paradigms (reverse vertical sinusoidal gratings, reverse horizontal sinusoidal gratings, reverse vertical square-wave gratings, brief-onset vertical sinusoidal gratings, reversal checkerboards, and oscillating expansion-contraction concentric rings) in SSVEP acuity assessment. Methods: Based on four indices of α + θ index, pupil diameter, National Aeronautics and Space Administration Task Load Index (NASA-TLX), and amplitude and SNR of SSVEPs, this study quantitatively evaluated mental fatigue in six SSVEP visual attention runs corresponding to six paradigms with 12 subjects. Results: These indices of mental fatigue showed a good agreement. The results showed that the paradigm of motion expansion-contraction concentric rings had a superior anti-fatigue efficacy than the other five paradigms of conventional onset mode or pattern reversal mode during prolonged SSVEP experiment. The paradigm of briefonset mode showed the lowest anti-fatigue efficacy, and the other paradigms of pattern reversal SSVEP paradigms showed a similar anti-fatigue efficacy, which was between motion expansion-contraction mode and onset mode. Conclusion: This study recommended the paradigm of oscillating expansioncontraction concentric rings as the stimulation paradigm in SSVEP visual acuity because of its superior anti-fatigue efficacy.

The slip surface has a significant effect on the tribological performances of a slider bearing and a hydrodynamic journal bearing. Less attention has been paid to the influence of a boundary slip on a hybrid journal bearing. However, hybrid journal bearings are increasingly used due to their intrinsic advantages. The effects of slip surface on the performances of a hybrid journal bearing are studied in this work. The affecting rule of both the slip-region location and the size on the load-carrying capacity is obtained. Only a well-designed slip surface could improve the tribological performances of hybrid journal bearings. This work could provide a valuable guide for the design of a slip surface in high-speed hybrid journal bearings.

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