About: Electric-vehicle battery is a(n) research topic. Over the lifetime, 1965 publication(s) have been published within this topic receiving 24522 citation(s).
Abstract: The electric vehicle (EV) battery systems are complex assemblies of dissimilar materials in which battery cells are connected using several thousand interconnect joints. Every single joint influences the functionality and efficiency of the whole battery system, making the joining process crucial. Laser welding is considered a desirable choice for EV battery manufacturing due to its non-contact nature, high energy density, precise control over the heat input, and ease of automation. However, incompatible thermos-physical properties of dissimilar materials used in battery tabs and interconnectors pose a significant challenge for achieving complete metallurgical bond. Furthermore, the formation of undesirable weld microstructures such as hard and brittle intermetallic compounds (IMCs) substantially undermines the structural, electrical, and thermal characteristics of battery joints. This paper reviews the fundamental difficulties and latest developments in dissimilar laser welding of steel-copper, steel-aluminum, aluminum-copper, and steel-nickel, some of the potential joint combinations in EV battery pack manufacturing. The weld microstructure and common metallurgical defects, as well as mechanical and electrical properties of joints are discussed. In addition, the effects of laser welding process parameters on the joint properties and the applicability of various interlayers and coatings in laser welding of battery materials are assessed.
TL;DR: An extended single particle model of a battery cell is constructed using the Pade approximation and the first-order Taylor expansion to simplify the conventional electrochemical mechanism model and indicates that the average standard deviation of the cell current in the NCM parallel-connected module can be reduced.
Abstract: Cell inconsistencies inevitably occur inside a battery module. Particularly, the inconsistencies in current distribution and heat generation in a parallel-connected battery module may lead to battery degradation and potential safety issues. Consequently, it is imperative to evaluate and reduce cell inconsistencies in a battery module. In this paper, an extended single particle model of a battery cell is constructed using the Pade approximation and the first-order Taylor expansion to simplify the conventional electrochemical mechanism model. On this basis, a multidomain electrochemical mechanism simulation model of a parallel-connected battery module is attained. Then, the influence of cell inconsistencies on the battery module voltage, internal current distribution and heat generation under different aging situation is assessed by a parameter sensitivity analysis method. Moreover, based on the contribution of each battery model parameter to the inconsistency of the parallel-connected battery module, a battery cell sorting method is proposed. Finally, this proposed sorting method for secondary applications of batteries is validated based on 15 aged batteries. Results indicate that the average standard deviation of the cell current in the NCM parallel-connected module can be reduced from 0.209 A to 0.060 A. The proposed approach is helpful to the fault analysis of electric vehicle battery modules, module level grading or the secondary applications of retired batteries.
Abstract: We design and fabricate a novel lithium-ion battery system based on direct contact liquid cooling to fulfill the application requirement for the high-safety and long-range of electric vehicles. By the immersion in the flowing silicone oil to achieve the highly efficient heat exchange, the NCM811 cells can be grouped without gap, and thereby the battery system achieves maximum volume efficiency. The mass and volume integration ratio of the battery system are 91% and 72%, respectively, which are 1.1 and 1.5 times that of the tube-based indirect liquid contact cooling system, respectively. Specifically, the temperature increment of the cells during 1C discharge does not exceed 13 ℃, and the dynamic temperature difference is less than 8.8 ℃. The results from simulation show that the maximum temperature rise and maximum temperature difference of the direct contact liquid cooling system are only 20%–30% of the indirect contact liquid cooling system. Particularly, the system can effectively prevent the thermal runaway propagation without any additional measures, owing to the high heat dissipation rate and oxygen isolation. The research has led to the successful construction of an oil-immersed battery system with high integration ratio and excellent safety, which provides a feasible solution for the demand of the high safety and high specific energy of the electric vehicle battery system.
01 Jan 2022
Abstract: Battery management implement cell balancing algorithms to equalize state of charge of series-connected cells in a battery pack. Balancing strategies range from passive, where a simple resistive circuit is used to drain current from the battery cell, to active, where sophisticated control schemes and advanced circuitry may be employed. Recent development of active balancing control strategies for a modular cell-balancing architecture utilize low-voltage bypass DC-DC converters and a shared low-voltage dc bus. Although these systems show promise in preliminary experiments, questions remain over the inherent stability properties of the architecture. This letter presents a stability analysis for an $N$ -cell battery module and provides insight for design of embedded controllers.
TL;DR: The results show that the HBP-ASS can obtain the exact solution to small-scale instances much more quickly than commercial branch-and-bound/cut solvers such as CPLEX and can find better solutions to large- scale instances within a shorter time than the existing heuristics – adaptive large neighborhood search.
Abstract: In this paper, a battery swap station location and routing problem with time windows and a mixed fleet of electric and conventional vehicles (BSS–MF–LRPTW) is proposed. This problem is motivated by a real-life logistics application by extending the existing electric vehicle battery swap stations location routing problem (BSS–EV–LRP). The BSS–MF–LRPTW aims to simultaneously determine the locations of battery swap stations (BSSs) and the routing plan of a mixed fleet under the driving range, the load capacity limitation, and time windows. An integer programming (IP) model is developed for the proposed BSS–MF–LRPTW. As there are a large number of variables and complicating constraints of the IP model, we break it up into the master problem and the subproblem, based on Danzig–Wolfe decomposition. To enhance the tractability of the problem, we follow up with a heuristic branch-and-price algorithm with an adaptive selection scheme (HBP-ASS), which integrates the exact policy with a heuristic strategy. The HBP-ASS develops heuristic versions of the dynamic programming algorithm by designing seven operators for heuristic label extension and dominance. An adaptive selection scheme is presented to decide which operator is employed. The performance of the proposed HBP-ASS is evaluated based on an extensive computational study. The results show that the HBP-ASS can obtain the exact solution to small-scale instances much more quickly than commercial branch-and-bound/cut solvers such as CPLEX. Also, for all tested cases, the HBP-ASS can find better solutions to large-scale instances within a shorter time than the existing heuristics – adaptive large neighborhood search. Furthermore, sensitivity analyses are carried out to provide managerial insights.