Battery Cost Research Articles

Battery Electric Vehicles: How Many Gears? A Technical–Economic Analysis

The large majority of electric cars have a single-speed gearbox, because electrified powertrains provide maximal power across a wide operating range, and single-speed simplifies construction and reduces capital costs. Nevertheless, multi-speed transmissions have also been developed for electric cars, and some of them have recently appeared as commercial products. This paper aims to compare, through some practical examples, solutions with single-speed and dual-speed transmissions. In particular, given the very smooth driving of electric cars, for dual-speed solutions, a dual-clutch gearbox was considered. Finally, a continuously variable transmission (CVT) was also used. Different solutions were analyzed from a technical–economic point of view, based on a simulation of the vehicle under standardized driving cycles, thus evaluating the capital and running electricity costs. The obtained results show that the comparison between the two solutions is very open, and in the majority of cases, the advantages in terms of efficiency overcome the disadvantages due to the additional capital costs. For a rather low battery cost of 150 €/kWh, the total cost reduction moves from about 100–150 € up to 1500–2000 €, depending on the electricity cost, along the whole vehicle lifespan.

Combined Operando Investigations Reveal Correlation between Formation Parameters and Transport Mechanisms in Solid Electrolyte Interphases of Lithium-Ion Battery Anodes

Despite its thickness being only in the nanometer range, the solid electrolyte interphase (SEI) of lithium-ion battery anodes has proven to be a crucial component, contributing critically to the battery’s longevity and long-term rate capability. This is due to the SEI’s passivating properties, protecting the battery electrolyte from further decomposition during operation while maintaining a good conductivity for lithium ions to be intercalated into the active anode material. Notwithstanding prolonged scientific efforts, a reliable SEI characterization is still very challenging, due to its fragile and inherently unstable nature which can easily lead to the introduction of artifacts in its evaluation, when dried, rinsed, or exposed to ambient atmospheric conditions. Thus, the relation between SEI formation parameters and the resulting morphological, compositional, and electrochemical properties is still poorly understood.To overcome the limitations of often-employed ex-situ methods, we developed an interlocked combination of several non-destructive operando characterization methods consisting of atomic force microscopy (AFM), electrochemical quartz-crystal microbalance (EQCM) and electrochemical impedance spectroscopy (EIS) to provide a plethora of information on the SEI’s morphological evolution, mass and thickness development and its viscoelastic and electrochemical properties like charge transfer resistance. All this information is gathered in the same electrochemical cell during the SEI formation on carbon model electrodes in typical LIB electrolytes containing 1 M LiPF6 in various carbonate mixtures.The combination of AFM, EQCM and EIS data gives us the opportunity to correlate the different growth modes during formation and resulting compositions of the SEI with its dominant transport mechanisms. Additional redox probe experiments help to further distinguish the transport parameters for lithium ions, solvent molecules, and redox molecules. A better understanding of these correlations allows battery researchers to find optimized SEI formation procedures and SEI forming additives, which reduce the formation duration during battery production and can thus contribute to lowering costs of lithium-ion batteries.

Versatile High-Valent Doping Strategy for Cathodes with Extremely High Ni Content

Currently, battery electric vehicles (BEVs) face significant challenges, such as shorter driving ranges than ICEVs and higher initial costs compared to ICEVs. As the performance and cost of Li-ion batteries (LIBs), that is, the core components of BEV, are mostly determined by the cathode material, automotive manufacturers are currently devoting improvements in energy density and lowering the cost of cathode materials. Ni-rich LiMO2 (M = Ni, Co, Mn, or Al) is a promising cathode material owing to its neartheoretical specific capacity and relatively low content of expensive cobalt. However, a high fraction of reactive Ni4+ ions at the cathode–electrolyte interfaces lead to capacity fading of Ni-rich cathodes.1,2 Therefore, a core–shell (CS) design encapsulating the Ni-rich region by a Ni-less shell is an effective approach for improving the cycling stability of the cathodes.3 However, with increasing average Ni content to increase the capacity, the thickness of the shell should be reduced or the Ni fraction of the shell will be inevitably higher, making it susceptible to interdiffusion, which flattens the concentration gradient during the lithiation process.4 Herein, the limit of the average Ni composition in the CS-type cathode is pushed to 94% via Ta doping, which suppresses interdiffusion by segregating the Ta-rich phases at the particle boundaries. Ta doping allows the maintenance of the highly aligned microstructure and the ordered intermixing structure of Li and transition metal ions, as well as the concentration gradient, over a wide lithiation temperature range. The Ta-doped CS-type cathode retains 92.6% of its initial capacity after 1000 cycles and exhibits resistance to damage from fast charging. Multifunctional Ta doping in the CS-type cathode provides a simple and all-around solution to maximize the electrochemical performance of Ni-rich cathodes, providing flexibility in the lithiation process. Reference s : [1] H.-J. Noh, S. Youn, C. S. Yoon, Y.-K. Sun, J. Power Sources, 2013, 233, 121.[2] H.-H. Ryu, K.-J. Park, C. S. Yoon, Y.-K. Sun, Chem. Mater. 2018, 30, 1155.[3] U.-H. Kim, H.-H. Ryu, J.-H. Kim, R. Mücke, P. Kaghazchi, C. S. Yoon, Y.-K. Sun, Adv. Energy Mater. 2019, 9, 1803902.[4] G.-T. Park, H.-H. Ryu, T.-C. Noh, G.-C. Kang, Y.-K. Sun, Mater. Today 2022, 52, 9.

Solvent-Free Lithium-Ion Batteries to High Volumetric Capacity via Carbon Nanotube-Coated Ni-Rich Cathodes

Until now, lithium-ion battery production technology relied on a slurry-based process using organic solvents (NMP), which is hazardous and is a major contributor to high cost and energy consumption in battery manufacturing processes. Among many studies to reduce battery costs, the dry electrode process that does not use organic solvents is attracting attention as a rising star. Dry electrode technology is one of the most promising processes for next-generation energy storage systems due to their eco-friendly production and lowering energy costs (US$ kWh−1). However, when nano-sized carbon black (CB) is used in a dry electrode process, electrochemical performance deteriorates due to insufficient conductivity in the electrode due to pin-point contact with the nickel-rich cathode. In addition, when CNTs used in the conventional wet process are applied to a dry electrode process, it is still difficult to prepare a dry electrode that is uniformly distributed within the electrodes due to its very high aggregation properties. Despite having innovative advantages, solvent-free processing remains a challenge due to these critical issues. Here, we fabricated a dry-type electrode by using poly-crystalline Ni-rich cathodes uniformly coated with CNTs (Carbon nanotubes), resulting in higher electrical conductivity than the electrodes prepared with the conventional wet process including carbon black (CB). In addition, as a result of minimizing the amount of PTFE binder in the electrode by eliminating the mixing of existing carbon black (CB), dry electrode manufacturing was enabled without crushing the Ni-rich cathodes even the fabrication of dense cathodes with extremely high active material content (99.7%) and high electrode density (4.0 g cm-3). The CNT-coated dry electrodes show a high Qvol of ~860 mAh cm-3 at a current rate of 0.2 C (~1.0 mA cm-2) compared to the conventional wet-process electrodes (98 wt% Ni-rich cathode; ~3.6 g cm-3). Furthermore, to demonstrate the practical LiBs operation, a 12cm2-sized pouch cell (>60mAh) was fabricated via dry process and exhibited excellent cycle performance (up to 80% after 400 cycles). We believe that this solvent-free lithium-ion battery via carbon nanotube-coated Ni-rich cathodes approach would be feasible and bring a new electrode design paradigm to the lithium-ion battery market. Figure 1

Coolant Temperature Indicators for Batteries in Electric Tractors and Vehicles

The paper accentuates a noticeable shift toward more economical and environmentally friendly electric vehicles within global agriculture, prompted by the growing prices of fuels and lubricants. The widespread adoption of electric vehicles for agricultural tasks encounters limitations, including such factors as performance, cost, service life and safety of traction batteries. The battery thermal management system assumes a key role in regulating battery life. (Research purpose) The study aims to analyze contemporary cooling systems for electric batteries, to identify the type of coolant capable of sustaining the optimal temperature of the traction battery under diverse climatic conditions. (Materials and methods) The paper examines the cooling systems and methods employed for battery temperature control. It provides a theoretical analysis of the effectiveness of thermal regulation for traction batteries, specifically exploring the potential to enhance battery performance through the maintenance of temperature at the required level. To facilitate comparison, several brands of electric vehicles from global automakers were selected. (Results and discussion) The paramount criterion for an effective cooling system is its capacity to rapidly dissipate heat during periods of elevated battery temperature while operating at a gradual pace during startup, thereby ensuring minimal impact on the efficiency of the electric vehicle. Based on this criterion, the paper provides statistical data regarding the modes and operating conditions of traction batteries, including their optimal operating temperature range. Calculations were conducted for three coolant types: ammonia, ethylene glycol and freon R134a. (Conclusions) Despite having an outlet temperature of 22.2 degrees Celsius, ethylene glycol registers 3.3 degrees higher than ammonia and 0.5 degrees higher than tetrafluoroethane, this refrigerant is suitable for application in copper piping.

Reducing the Ecological Footprint and charging cost of electric vehicle charging station using renewable energy based power system

Ecological Footprint of electric vehicle (EV) charging stations primarily focuses on three parameters: direct/indirect emissions, manpower and physical land requirement. Electric vehicle charging stations rely on electricity to charge EV batteries, and electricity source can significantly influence their environmental impact. The Ecological Footprints of EV charging station is estimated as 40.69 gha. The potential EF reduction of EV charging station is 89.9 % by using proposed hybrid power system. The Ecological Footprint of EV charging is about 3.1 × 10−4 gha/kWh of batteries charging. However, proposed hybrid system may reduce environmental impact of battery charging as 3.15×10−5 gha/kWh of batteries charging. The lifecycle cost of batteries charging is estimated as 0.168 $/kWh. It may reduce as 0.107 $/kWh of batteries charging with installation of proposed hybrid system. Thus, it is crucial to promote the use of renewable energy sources to power electric vehicle charging stations and minimize their environmental impact.

Recent Advances in Bromine Complexing Agents for Zinc–Bromine Redox Flow Batteries

The development of energy storage systems (ESS) has become an important area of research due to the need to replace the use of fossil fuels with clean energy. Redox flow batteries (RFBs) provide interesting features, such as the ability to separate the power and battery capacity. This is because the electrolyte tank is located outside the electrochemical cell. Consequently, it is possible to design each battery according to different needs. In this context, zinc–bromine flow batteries (ZBFBs) have shown suitable properties such as raw material availability and low battery cost. To avoid the corrosion and toxicity caused by the free bromine (Br2) generated during the charging process, it is necessary to use bromine complexing agents (BCAs) capable of creating complexes. As an overview, the different BCAs used have been listed to compare their behavior when used in electrolytes in ZBFBs. In addition, the coulombic and energy efficiencies obtained have been compared.

Techno-economic analysis of hydrogen production via photovoltaic, battery and electrolysis: plant sizing and hydrogen cost.

Photovoltaic reached more than 20% panel efficiency and less than 20% system efficiency losses and 1 M€/MW cost. Similar cost is reached by electrolyzer meanwhile the efficiency can be more than 60% from 3% to 110% of the nominal power. Battery cost reached less than 0.5 M€/MWh meanwhile efficiency is higher and lifetime has reached more than 20.000 cycle if uses are within 20-80% of the state of charge. With these values the battery can be downsized (owing to the large % of electrolyzer nominal power) but still hydrogen production cost from photovoltaic is not competitive. These paper analyses what can be the better size among photovoltaic, battery and electrolyzer in order to reach the lowest hydrogen production cost with a sensitivity analysis on representative parameters (efficiencies, CAPEX and OPEX) for these technologies.

Research on energy management and control for six-wheel-drive electric bus rapid transit with photovoltaic-battery-supercapacitor

Electric Bus Rapid Transit is an effective solution to traffic congestion and environmental pollution. At present, Electric Bus Rapid Transit needs to be equipped with a large number of power batteries, which brings the key problems of long charging time, short driving range, and high comprehensive utilization cost. To solve the above problems, a novel six in-wheel motors driving Electric Bus Rapid Transit scheme with photovoltaic cells, lithium-ion batteries and supercapacitors (SWEBRT-PBS) is studied, constrained by the cost and comprehensive energy efficiency of vehicle. First, the system architecture for hybrid energy storage system composed of photovoltaic cells, lithium-ion batteries and supercapacitors (PBS) is analyzed. The life cycle cost function for PBS based on the degradation cost of lithium-ion batteries and the electricity cost of each energy source is proposed. The dynamic programming algorithm is employed to optimize the life cycle cost function of PBS, and then to obtain the optimal size of matches for supercapacitors. Second, the fixed step disturbance observation method is adopted to ensure stable power output in the maximum power point tracking controller of photovoltaic cells based on the vehicle application environment. Third, the power control rules are extracted based on the optimization results of dynamic programming algorithm, and the power allocation strategy for PBS with dynamic programming algorithm joint rules is formulated. Fourth, the overall efficiency function for driving system is established and optimized based on the sequential quadratic programming algorithm. The collaborative optimization strategy for SWEBRT-PBS is developed based on the corresponding optimization results, PBS operating modes and vehicle operating modes. The results show that the SWEBRT-PBS can reduce the number of lithium-ion batteries, thereby reducing the vehicle mass by 1.27 % and increasing the vehicle space utilization by 1.81 %. In addition, the comprehensive energy efficiency of vehicle can be improved by 28.79 %.

Prioritized experience replay based deep distributional reinforcement learning for battery operation in microgrids

Reinforcement Learning (RL) provides a pathway for efficiently utilizing the battery storage in a microgrid. However, traditional value-based RL algorithms used in battery management focus on formulating the policies based on the reward expectation rather than its probability distribution. Hence the scheduling strategy is solely based on the expectation of the rewards rather than the distribution. This paper focuses on scheduling strategy based on probability distribution of the rewards which optimally reflects the uncertainties in the incoming dataset. Furthermore, the prioritized experience replay samples of the training experience are used to enhance the quality of the learning by reducing bias. The results are obtained with different variants of distributional RL algorithms like C51, Quantile Regression Deep Q-Network (QR-DQN), Fully Quantizable Function (FQF), Implicit Quantile Networks (IQN) and rainbow. Moreover, the results are compared with the traditional deep Q-learning algorithm with prioritized experienced replay. The convergence results on the training dataset are further analyzed by varying the action spaces, using randomized experience replay and without including the tariff-based action while enforcing the penalties for violating battery SoC limits. The best trained Q-network is tested with different load and PV profiles to obtain the battery operation and costs. The performance of the distributional RL algorithms is analyzed under different schemes of Time of Use (ToU) tariff. QR-DQN with prioritized experience replay has been found to be the best performing algorithm in terms of convergence on the training dataset, with least fluctuation in validation dataset and battery operations during different tariff regimes during the day.

Recycling of spent lithium–ion battery graphite anodes via a targeted repair scheme

When lithium–ion batteries (LIBs) reach the end of their life, a lot of hazardous wastes will be generated. Unfortunately, the recovery of spent graphite (SG) anodes is always neglected despite the rather high production cost of battery–grade graphite. In this work, we for the first time propose a novel targeted repair scheme by systematically characterizing and analyzing the structure and composition of SG. The results show that the repair scheme achieves effective SG repair and the repaired graphite anode displays excellent lithium storage performance, which can be comparable to that of commercial graphite. In addition, the scheme is evaluated to reduce energy consumption by 79 % and harmful pollutant emission by 90 % as compared to previously reported solutions. Obviously, our work provides a feasible solution for the recovery of graphite anodes from spent LIBs by understanding the failure characteristics of graphite anodes.

A total cost of ownership analysis of zero emission powertrain solutions for the heavy goods vehicle sector

Transport-related activities represented 34% of the total carbon emissions in the UK in 2022 and heavy-duty vehicles (HGVs) accounted for one-fifth of the road transport greenhouse gas (GHG) emissions. Currently, battery electric vehicles (BEVs) and hydrogen fuel cell electric vehicles (FCEVs) are considered as suitable replacements for diesel fleets. However, these technologies continue to face techno-economic barriers, creating uncertainty for fleet operators wanting to transition away from diesel-powered internal combustion engine vehicles (ICEVs). This paper assesses the performance and cost competitiveness of BEV and FCEV powertrain solutions in the hard-to-abate HGV sector. The study evaluates the impact of battery degradation and a carbon tax on the cost of owning the vehicles. An integrated total cost of ownership (TCO) model, which includes these factors for the first time, is developed to study a large retailer's HGV fleet operating in the UK. The modelling framework compares the capital expenditures (CAPEX) and operating expenses (OPEX) of alternative technologies against ICEVs. The TCO of BEVs and FCEVs are 11% to 33% and 37% to 78% higher than ICEVs; respectively. Despite these differences, by adopting a longer lifetime for the vehicle it can effectively narrow the cost gap. Alternatively, cost parity with ICEVs could be achieved if BEV battery cost reduces by 56% or if FCEV fuel cell cost reduces by 60%. Besides, the pivot point for hydrogen price is determined at £2.5 per kg. The findings suggest that BEV is closer to market as its TCO value is becoming competitive, whereas FCEV provides a more viable solution than BEV for long-haul applications due to shorter refuelling time and lower load capacity penalties. Furthermore, degradation of performance in lithium-ion batteries is found to have a minor impact on TCO if battery replacement is not required. However, critical component replacement and warranty can influence commercial viability. Given the high costs, we propose financial incentives and vehicle tax reforms to reduce costs of critical components that will encourage the roll-out of zero emission HGVs.

Historical and prospective lithium-ion battery cost trajectories from a bottom-up production modeling perspective

Lithium-ion batteries (LiBs) are pivotal in the shift towards electric mobility, having seen an 85 % reduction in production costs over the past decade. However, achieving even more significant cost reductions is vital to making battery electric vehicles (BEVs) widespread and competitive with internal combustion engine vehicles (ICEVs). Recent trends indicate a slowdown, including a slight cost increase in LiBs in 2022. This study employs a high-resolution bottom-up cost model, incorporating factors such as manufacturing innovations, material price fluctuations, and cell performance improvements to analyze historical and projected LiB cost trajectories. Our research predicts potential cost reductions of 43.5 % to 52.5 % by the end of this decade compared to 2020. Furthermore, reaching cost parity between BEVs and ICEVs is expected in the latter half of this decade, contingent on a total installed capacity of 3500 to 4100 GWh.year−1 across giga-factories. The determinants influencing these cost reductions evolve over time, with historical significance placed on savings in cathode materials and anticipated future importance on minimizing scrap rates. This research offers valuable insights for policymakers and investors in the LiB industry, aiding informed decision-making.

Optimal sizing and techno-economic analysis of the hybrid PV-battery-cooling storage system for commercial buildings in China

Energy systems for flexibility in buildings are hybrid, primarily including rooftop photovoltaics (PV), cooling storage, and battery. Considering their techno-economic patterns, this research establishes an optimization model to determine the optimal technology portfolio and financial advantages of PV-battery-cooling storage systems for commercial buildings in China. The analysis of all cases indicates that cooling storage outperforms batteries in economic benefits, suggesting the prioritization of cooling storage installation. Once the optimal cooling storage rate is exceeded, it is advisable to proceed with batteries. Meanwhile, PV integration significantly enhances the system efficiency and promotes battery utilization. For example, a 40% PV penetration combined with a 0.006 $/(a·kWhe) energy storage investment results in an impressive 27.3% cost reduction in a Beijing mall, while the optimal cooling storage rate decreases from 55% to 40%. Furthermore, the study emphasizes the impact of tariff patterns and electricity demand on the economic feasibility of hybrid energy systems. The museum's substantial annual cooling requirements and nighttime loads make cooling storage favorable, with PV less suitable than the mall and office. Notably, cities like Beijing, Shanghai, Chongqing, and Guangzhou exhibit considerable peak-to-valley tariff differences, yielding higher economic benefits ranging from 23% to 27%. Finally, as battery costs decline and electricity price becomes more volatile, the battery would gradually replace cooling storage, especially when battery cost drops from 150 $/kWh to 70 $/kWh.

Life-cycle assessment of batteries for peak demand reduction

At present, a life-cycle assessment of energy storage systems (ESSs) is not widely available in the literature. Such an assessment is increasingly vital nowadays as ESS is recognized as one of the important equipment in power systems to reduce peak demands for deferring or avoiding augmentation in the network and power generation. As the battery cost is still very high at present, a comprehensive assessment is necessary to determine the optimal capacity of ESS so that the maximum financial gain is achievable at the end of the batteries’ lifespan. Therefore, an effective life-cycle assessment is proposed in this paper to show how the optimum capacity of ESS can be determined such that the maximum net financial gain is achievable at the end of the batteries’ lifespan when ESS is used to perform peak demand reductions for the customer or utility companies. The findings reveal the positive financial viability of ESS on the power grid, otherwise the projection of the financial viability is often seemingly poor due to the high battery cost with a short battery lifespan. An improved battery degradation model is used in this assessment, which can simulate the battery degradation accurately in a situation whereby the charging current, discharging current, and temperature of the batteries are intermittent on a site during peak demand reductions. This assessment is crucial to determine the maximum financial benefits brought by ESS.

Optimal Dispatch Strategy for Electric Vehicles in V2G Applications

The overutilization of electric vehicles (EVs) has the potential to result in significant challenges regarding the reliability, contingency, and standby capabilities of traditional power systems. The utilization of renewable energy distributed generator (REDG) presents a potential solution to address these issues. By incorporating REDG, the reliance of EV charging power on conventional energy sources can be diminished, resulting in significant reductions in transmission losses and enhanced capacity within the traditional power system. The effective management of the REDG necessitates intelligent coordination between the available generation capacity of the REDG and the charging and discharging power of EVs. Furthermore, the utilization of EVs as a means of energy storage is facilitated through the integration of vehicle-to-grid (V2G) technology. Despite the importance of the V2G technology for EV owners and electric utility, it still has a slow progress due to the distrust of the revenue model that can encourage the EV owners and the electric utility as well to participate in V2G programs. This study presents a new wear model that aims to precisely assess the wear cost of EV batteries, resulting from their involvement in V2G activities. The proposed model seeks to provide EV owners with a precise understanding of the potential revenue they might obtain from participating in V2G programs, hence encouraging their active engagement in such initiatives. Various EV battery wear models are employed and compared. Additionally, this study introduces a novel method for optimal charging scheduling, which aims to effectively manage the charging and discharging patterns of EVs by utilizing a day-ahead pricing technique. This study presents a novel approach, namely, the gradual reduction of swarm size with the grey wolf optimization (GRSS-GWO) algorithm, for determining the optimal hourly charging/discharging power with short convergence time and the highest accuracy based on maximizing the profit of EV owners.

Low-Index Facet Polyhedron-Shaped Binary Cerium Titanium Oxide for High-Voltage Aqueous Zinc-Vanadium Redox Flow Batteries.

Aqueous zinc-vanadium hybrid redox flow battery systems are an efficient strategy to address the problems of low voltage and high cost of conventional all-vanadium redox flow batteries. However, the low electrochemical activity of carbon-based electrodes toward a vanadium redox reaction limits the performance of redox flow batteries. In this study, polyhedral binary cerium titanium oxide (Ce2/3TiO3, CTO) is synthesized using molten salt synthesis. CTO is fabricated by adjusting the temperature and composition. Notably, the prepared CTO obtained at 1000 °C shows the highest catalytic activity for a VO2+/VO2+ redox reaction. Further, CTO is prepared as a composite electrocatalyst and applied to a high-voltage aqueous zinc-vanadium redox flow battery. The cell adopts an alkali zinc electrolyte containing a Zn/[Zn(OH)4]2- redox pair and exhibits a high operating voltage of 2.26 V. Remarkably, a zinc-vanadium redox flow battery using the composite electrocatalyst exhibits a high energy density of 42.68 Wh L-1 at 20 mA cm-2 and an initial voltage efficiency of 90.3%. The excellent cell performance is attributed to structural defects caused by A-site deficiency in the perovskite oxide structure as well as oxygen vacancies resulting from the low valence state of the metal ion, which enhance the catalytic activity of the vanadium ions.

Numerical Study on a Liquid Cooling Plate with a Double-Layer Minichannel for a Lithium Battery Module.

The liquid cooling system of lithium battery modules (LBM) directly affects the safety, efficiency, and operational cost of lithium-ion batteries. To meet the requirements raised by a factory for the lithium battery module (LBM), a liquid cooling plate with a two-layer minichannel heat sink has been proposed to maintain temperature uniformity in the module and ensure it stays within the temperature limit. This innovative design features a single inlet and a single outlet. To evaluate the performance of the liquid cooling system, we considered various discharge rates while taking into account the structure, flow rate, and temperature of the coolant. Our findings indicate that at a mass outflow rate of 20 g/s, a better cooling effect and lower power consumption can be achieved. An inlet temperature of 20 °C, close to the initial temperature of the battery string, may be the most appropriate because a higher temperature of the coolant will cause a higher temperature of LBM, so far as to exceed the safe threshold value. In the case of larger rate discharge, the design of a double-layer MCHS at the bottom and an auxiliary one at the side can effectively reduce the maximum temperature LBM (within 28 °C) and maintain the temperature difference in the single cell at approximately 4 °C. In the case of non-constant discharges, the temperature difference between cells increases with the maximum temperature. When the discharge rate is reduced, the large temperature difference helps the temperature to drop rapidly. This can provide guidance for the design of cooling systems for the LBM.

An extensive review on hybrid electric vehicles powered by fuel cell-enabled hybrid energy storage system.

To overcome the air pollution and ill effects of IC engine-based transportation (ICEVs), demand of electric vehicles (EVs) has risen which reduce *gasoline consumption, environment degradation and energy wastage, but barriers-short driving range, higher battery cost and longer charging time-slow down its wide adoptions and commercialization. Although to overcome such issues, EV variants -HEVs and PHEVs-were also brought into the market but not that successful either. The use of ICE in HEVs and PHEVs increases fossil fuel dependency. Thus, the research focus shifted towards fuel cell-powered electric vehicles (FCEVs) which offer negligible emission and higher efficiency than EV variants. Though a moderate research work has been done on FCEVs, still its wide expansion is limited, facing severe challenges commonly related to fuel cost, selection of energy units, power electronic interfacing, component sizing and energy management. This paper presents an extensive exploration on EV variants, their issues, an in-depth comparison of latest topologies for FCEVs and optimum arrangement of HESS, designed by energy unit's integration, i.e. FC, battery and UCs, to encounter the dynamic power demand and develop a performant model for transportation. In last, progress and possible future research areas are discussed. In short, this paper reveals all contemporary information of FCHEV technology to the scientists and scholars who are working in this particular arena.

Electrochemical heat engine based on neutralization flow battery for continuous low-grade heat harvesting

An enormous amount of energy is wasted annually in the form of low-grade heat with a temperature below 100 °C. Recently, studies on heat harvesting have focused on semiconductor-based devices, but nowadays, electrochemical devices based on a thermally regenerative cycle (TREC) are growing in importance due to their superior thermoelectric power. Among them, TRECs based on flow batteries (TREC-FB) are especially attractive since they offer more flexibility for heat harvesting and an opportunity for continuous heat-to-power (HTP) conversion. However, this technology struggles due to the high cost of the flow batteries they are based on, particularly the costly electrolyte solutions. We offer a novel approach for continuous heat harvesting based on the emerging technology of the neutralization flow battery (NFB) with low-cost and highly soluble electrolytes, which consists of two hydrogen electrodes immersed in acid and base solutions. Since values of both electrodes’ temperature coefficient differ, NFB can be used for heat harvesting: the cell temperature coefficient varies in the range of 0.64–1.1 mV K−1. Here, we present both intermittent and continuous TREC based on NFB, with a focus on the latter due to its convenience. Our study on continuous heat harvesting shows that for a temperature difference between the heat source and heat sink of 25 °C, one can achieve power of 10–24 μW cm−2, and efficiency of 1.4–2.9 % even without any recuperation. Alternatively, increasing the temperature difference to 55 °C results in a 6-fold increase in power at 1.6–3.5 % efficiency. We found that due to the low freezing point of the electrolytes, one can obtain even higher HTP performance if the heat sink temperature is about 0 °C. Additionally, we examined NFB performance under various temperatures and proposed low-grade heat harnessing using intermittent NFB heating/cooling to enhance its cycling performance. We believe that the proposed approaches facilitate further development of high-performance TREC-FB and thereby extend the possibilities for heat harvesting.