Purpose The purpose of this study was to analyze the environmental trade-offs of cascading reuse of electric vehicle (EV) lithium-ion batteries (LIBs) in stationary energy storage at automotive end-of-life. Methods Two systems were jointly analyzed to address the consideration of stakeholder groups corresponding to both first (EV) and second life (stationary energy storage) battery applications. The environmental feasibility criterion was defined by an equivalent-functionality lead-acid (PbA) battery. A critical methodological challenge addressed was the allocation of environmental impacts associated with producing LIBs across the EV and stationary use systems. The model also tested sensitivity to parameters such as the fraction of battery cells viable for reuse, service life of refurbished cells, and PbA battery efficiency. Results and discussion From the perspective of EV applications, cascading reuse of an LIB in stationary energy storage can reduce net cumulative energy demand and global warming potential by 15 % under conservative estimates and by as much as 70 % in ideal refurbishment and reuse conditions. When post-EV LIB cells were compared directly to a new PbA system for stationary energy storage, the reused cells generally had lower environmental impacts, except in scenarios where very few of the initial battery cells and modules could be reused and where reliability was low (e.g., life span of 1 year or less) in the secondary application. Conclusions These findings demonstrate that EV LIB reuse in stationary application has the potential for dual benefit-both from the perspective of offsetting initial manufacturing impacts by extending battery life span as well as avoiding production and use of a less-efficient PbA system. It is concluded that reuse decisions and diversion of EV LIBs toward suitable stationary applications can be based on life cycle centric studies. However, technical feasibility of these systems must still be evaluated, particularly with respect to the ability to rapidly analyze the reliability of EV LIB cells, modules, or packs for refurbishment and reuse in secondary applications.

Offering a consistent, systematic approach to capacitive, piezoelectric and magnetic MEMS, from basic electromechanical transducers to high-level models for sensors and actuators, this comprehensive textbook equips graduate and senior-level undergraduate students with all the resources necessary to design and develop practical, system-level MEMS models. The concise yet thorough treatment of the underlying principles of electromechanical transduction provides a solid theoretical framework for this development, with each new topic related back to the core concepts. Repeated references to the shared commonalities of all MEMS encourage students to develop a systems-based design perspective. Extensive use is made of easy-to-interpret electrical and mechanical analogs, such as electrical circuits, electromechanical two-port models and the cascade paradigm. Each chapter features worked examples and numerous problems, all designed to test and extend students' understanding of the key principles.

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To access ground truth degradation information, we simulatedcharge and discharge cycles of automotive lithium ion batteriesin their healthy and degrading states and used this informationto determine performance of an autoencoder-basedanomaly detector. The simulated degradation mechanism wasan abrupt increase in the battery’s rate of time-dependent capacityfade. The neural network topology was based on onedimensionalconvolutional layers. The decision-support system,based on the sequential probability ratio test, interpretedthe anomaly generated by the autoencoder. Detection timeand time to failure were the metrics used for performanceevaluation. Anomaly detection was evaluated on five differentsimulated progressions of damage to examine the effectsof driving profile randomness on performance of the anomalydetector.

Lithium ion battery modules have significant capacity left after their useful life in transportation applications. This empirical study successfully tested the used modules in secondary grid applications in laboratory conditions. The selection of the secondary application was based on the construction features of the modules and the growing need for storage in grid operations. Description of the laboratory setup is provided in the context of a critical practical constraint where the battery management system and the usage and health history are not available to the secondary battery integrator. Charge and discharge profiles were developed based upon applications for peak shaving and firming renewables. Techno-economic analysis was focused on peak shaving at the utility level, considering a growing need for an affordable and environmentally friendly replacement to the traditional solutions based on environmentally costly peaker plants. The analysis showed strong evidence that near-term and future storage markets will be characterized by a large mismatch between the demand and supply of reused batteries from automotive primary applications for peak-shaving purposes in the generation side. The paper includes a discussion on successful adoption of cascaded use of batteries and their potential to reduce both economic and environmental cost of peak shaving.

The economic value of high-capacity battery systems, being used in a wide variety of automotive and energy storage applications, is strongly affected by the duration of their service lifetime. Because many battery systems now feature a very large number of individual cells, it is necessary to understand how cell-to-cell interactions can affect durability, and how to best replace poorly performing cells to extend the lifetime of the entire battery pack. This paper first examines the baseline results of aging individual cells, then aging of cells in a representative 3S3P battery pack, and compares them to the results of repaired packs. The baseline results indicate nearly the same rate of capacity fade for single cells and those aged in a pack; however, the capacity variation due to a few degrees changes in room temperature (≃±3 ∘ C) is significant (≃±1.5% of capacity of new cell) compared to the percent change of capacity over the battery life cycle in primary applications (≃20–30%). The cell replacement strategies investigation considers two scenarios: early life failure, where one cell in a pack fails prematurely, and building a pack from used cells for less demanding applications. Early life failure replacement found that, despite mismatches in impedance and capacity, a new cell can perform adequately within a pack of moderately aged cells. The second scenario for reuse of lithium ion battery packs examines the problem of assembling a pack for less-demanding applications from a set of aged cells, which exhibit more variation in capacity and impedance than their new counterparts. The cells used in the aging comparison part of the study were deeply discharged, recovered, assembled in a new pack, and cycled. We discuss the criteria for selecting the aged cells for building a secondary pack and compare the performance and coulombic efficiency of the secondary pack to the pack built from new cells and the repaired pack. The pack that employed aged cells performed well, but its efficiency was reduced.

We describe an approach to estimate state-of-charge and faded capacity of cobalt-based lithium-ion cell based on timedomain analysis of a short-term transient. This approach requires a relatively short-duration test and is suitable for repurposing cells for less demanding applications. The successful estimation requires previous characterization of the cells for the given family because lithium ion chemistries differ significantly. Two algorithms were considered for estimation of unknown state-of-charge and capacity: Bayesian inference and boosted regression trees. The achieved accuracy was 95 % of capacity estimations; estimations were within 2 % of the nominal cell capacity from the true value.