One of the most common yet complex questions for electric vehicle (EV) owners is, “How long does it take to charge an EV?” While straightforward on the surface, this question requires a nuanced answer due to the many variables at play. Factors such as battery size, maximum charging rates of the EV and charging station, and environmental conditions all influence charging time.
In 2022, the Chinese battery manufacturer CATL introduced its Qilin batteries, supporting 4C fast charging and enabling a 10-minute charge for a 400 km driving range. According to 36kr (1), CATL aims to launch a 6C charging battery later this year, which would allow even faster charging. Other leading battery manufacturers, such as BYD, are also believed to pursue 6C fast-charging technologies. Here, the “C-rate” describes the charging speed of batteries, with 6C referring to a full charge in 1/6 of an hour (10 minutes).
Fast charging has the potential to significantly alleviate “range anxiety,” a common concern among EV owners. While internal combustion engine (ICE) vehicles typically achieve around 640 km (400 miles) on a full tank, high-performance battery electric vehicles (BEVs) with large battery sizes (100+ kWh) are reaching comparable ranges. Some models, like the Zeeker 001, claim ranges of up to 1000 km (600 miles) per charge. However, range anxiety persists, not due to the total range but the scarcity of charging stations and the time required to charge. While ICE drivers spend about five minutes refueling, EV owners generally need at least 30 minutes for a 2C charge. Increasing the charging rate to 6C would reduce the waiting time to 10 minutes, comparable to a quick refuel.
In June 2024, EVE Energy introduced the Omnicell 6C, a cylindrical cell offering 300 km of range after a 5-minute charge (2). But is such rapid charging physically feasible? A simplified calculation using Fick’s Law offers insight into this. The diffusion time t for lithium ions (Li+) is approximated by: t≈x^2/2D, where x represents the diffusion distance, and D is the diffusion coefficient. Assuming a cathode, separator, and anode thickness of 70 μm, 20 μm, and 70 μm, respectively, with an average tortuosity of 4, the diffusion length x totals 0.064 cm. With a Li+ diffusion coefficient D estimated at 5×10−6 cm2/s, the diffusion time is approximately 6.8 minutes—suggesting that 4–6C charging may indeed be feasible for lithium-ion batteries, even if certain rate-limiting steps are not accounted for in this simplified calculation.
Despite the promise of 6C charging, several limitations exist. From a materials standpoint, lithium-ion diffusion within solid materials is significantly slower than in liquid electrolytes, constraining practical charging rates, especially in graphite anodes. Additionally, at high C-rates, lithium ions may accumulate on the anode surface instead of diffusing into the balk, forming parasitic lithium dendrites. Low temperatures exacerbate this problem, increasing the risk of lithium plating and presenting a major challenge for EVs. Battery makers are developing materials and electrolytes tailored for fast charging, such as CATL’s Freevoy hybrid battery, which combines lithium-ion and sodium-ion cells for enhanced low-temperature performance (3).
Thermal management is another crucial factor, as fast charging can generate substantial heat. According to Joule’s law (P=I^2R), heat production P is proportional to the square of the current I, making effective cooling essential for 6C charging rates. Traditional air cooling may be insufficient due to air’s low thermal conductivity and capacity, necessitating liquid (immersion) cooling systems. Examples include BYD’s direct cooling and direct heating system and CATL’s multifunctional elastic cooling interlayers, designed to maintain optimal battery temperatures under high charge currents (4). Infrastructure is also a bottleneck. As of now, 6C-compatible charging stations are limited, and even 4C infrastructure is not yet widely deployed. Charging a 100 kWh battery at 6C demands around 600 kW power. Ten EVs charging at this rate would impose a 6 MW load, equivalent to the power needs of a small factory. Integrating 6C charging at scale would therefore necessitate substantial upgrades to electrical infrastructure, including transformers, switchgear, and distribution systems (5). Collaboration between battery manufacturers and energy providers will be essential to address these challenges.
The commercialization of lithium-ion batteries has benefited from over thirty years of relentless engineering optimization. By innovating across materials, system design, and infrastructure, the industry continues to push battery performance and charging capabilities to new heights. While 6C fast charging holds the potential to transform the EV landscape and offer new playgrounds for emerging technologies like solid-state batteries and vehicle-to-grid systems, it also introduces complex challenges. As the industry explores solutions, careful evaluation of feasibility and readiness is crucial for successful adoption.
Working at the Department of Chemistry–Ångström Laboratory, I immediately decided to choose a paper related to my subject, “The Goal of Doctoral Education in Chemistry: Faculty Perspectives”, published in the Journal of Chemical Education, American Chemical Society (J. Chem. Educ. 2024, 101, 3050–3061).
This paper summarizes and evaluates the faculty’s perspectives on the overarching goals of doctoral education in chemistry (DEC) through comprehensive national-wide faculty interviews conducted in the US. Six interrelated goals were identified: two primary goals (preparing students to be competitive for future careers and cultivating independent scientists) and four secondary goals (fostering expertise, nurturing critical thinkers, generating novel research, and contributing to institutional rankings). Further analysis yielded three key insights: preparing students for a career and preparing students to be independent scientists are convergent goals; students may be receiving imbalanced preparation for their actual careers; faculty expressed varying levels of confidence in identifying program goals.
Significant point (from the paper): According to a commissioned report from the American Chemical Society (ACS), the goal of DEC is to educate students to be adept at addressing societal challenges and imparting knowledge to succeeding generations. Many (specific) goals, including generating new knowledge, advancing technology, promoting society advancements, and broader national project of employment, are pursued by DEC.
My own reflection: It is interesting to compare the DEC goal between the US and the Swedish education systems. Doctoral education in Sweden is regulated by the Higher Education Act (1992:1434) and the Higher Education Ordinance (1993:100). These are supplemented by the following local regulations: Guidelines for doctoral studies at Uppsala University (UFV 2022/728), Admission and grading regulations for doctoral studies and study programmes at Uppsala University (UFV 2022/729) and Guidelines for doctoral (third cycle) education at the Faculty of Science and Technology (TEKNAT 2021/301). According to the Higher Education Act, doctoral education shall develop the knowledge and skills needed to be able to conduct research independently. Through supervision and writing of the thesis, the doctoral student shall be prepared for a scientifically independent and critical professional role within areas in which a high level of scientific knowledge and research abilities are essential. These goals are generally aligned with the American DEC goals. This consensus emphasizes the importance of producing graduates with breadth and depth of knowledge and skills for future independent careers.
Significant point: While all participants emphasized the crucial role of faculty mentorship in DEC career preparation, the extent of this preparation often depends on the student’s research advisor. This variability is concerning, as not all faculty prioritize career preparation, potentially leaving students uninformed about available careers or ill-prepared for them…There is a misalignment between those careers for which faculty prepare students and those genuinely available…The annual number of Ph.D. chemistry job-seekers includes more than 3,000 newly awarded chemistry doctoral degrees in addition to an unknown number of postdocs and existing faculty. This is in contrast to approximately 550 to 600 research-focused and teaching-focused academic careers being advertised each year (in the US).
My own reflection: Faculty mentorship plays a critical role in shaping students’ career paths, where students rely heavily on supervisors for guidance, networking, and professional development. Ideally, supervisors should align career goals with the students, making sure that all students receive adequate exposure to both academic and non-academic career paths. In reality, however, some supervisors may not prioritize the latter for their students, or they do not have sufficient experience themselves with non-traditional career trajectories. Here, it would be nice for institutions to offer career support based on their alumni network and/or collaborators outside academia. Meanwhile, teaching experience during DEC greatly benefits students’ future career development, as it provides necessary training to develop skills in communication and mentoring. According to the general study syllabus, doctoral students who teach should undergo thorough pedagogic training for higher education. A five-week Academic Teacher Training course (7.5 credit) is often included in doctoral students’ study plan.
Significant point: Literature demonstrates the importance of both breadth and depth in students’ training as numerous research and/or society challenges transcend conventional disciplinary boundaries. However, a potential limitation arises if DEC mandates single-advisor, single-project assignments, limiting exposure to breath.
My own reflection: I fully agree with the authors’ concern: mandating a single-advisor, single-project structure can be very limiting for doctoral students. They may not gain the broader perspective needed to tackle multi-faceted challenges, with knowledge from data science, ethics, environmental studies, or public policy. In this regard, co-supervisors may often bring new perspectives to the DEC, widening the scope of expertise. Doctoral students are also encouraged to work on side projects or engage in broader research initiatives. This will provide a balance between the depth of expertise in a primary research field and the breadth of knowledge and skills across related areas, better preparing students for the complexity of societal challenges.
Significant point: Participant 5 clearly states that their university’s goal for the program was different than their own; to get good metrics for university rankings…Balancing the pursuit of institutional prestige with the goals of DEC poses an intriguing facet of the discourse surrounding chemistry programs. The interview indicates that the institution’s ranking doesn’t really impact whether institution rank is part of the institution’s/program’s goal.
My own reflection: This is an interesting point. Indeed, high subject ranking attracts more high-quality prospective students while offering better employability for graduates. However, the associated prestige tends to emphasize metrics like research funding, publication output, and faculty reputation, which does not necessarily reflect the quality of student training or the long-term success of DEC programs. It is crucial that the program should prioritize student success over purely institutional prestige. The holistic development of students, e.g., equipping them with research skills, fostering mentorship, and preparing them for a wide array of career opportunities, should be the fundamental focus of DEC.
Significant point: The need for tailoring training programs to meet these goals is evident, highlighting the importance of individualized career development plans and mentorship to navigate these diverse pathways effectively.
My own reflection: At Uppsala University, such an individualized career development plan is known as the individual study plan (ISP). The principal supervisor, in consultation with the professor responsible for doctoral studies (FUAP), is responsible for drawing up an ISP prior to the student’s admission. Such a document shall contain a timetable for the doctoral studies, a specification of how supervision is organized, and a description of the undertakings of the doctoral student and the department during the period of studies. The ISP must be revised at least annually in collaboration between the doctoral student and their supervisor. I recently finished revising the ISPs with my two PhD students. The revision of ISP offers an excellent opportunity for us to sit down and reflect on each other’s performance and make logical and achievable goals for the year to come.
]]>It is also worth mentioning that in connection with activity, excess Gibbs free energy, defined as the difference between the actual Gibbs free energy of the solution and that of an ideal solution with the same composition at the same temperature and pressure, measures the deviation of a real solution from an ideal solution. Both concepts are important in understanding the behavior of solutions in thermodynamics.
In today’s seminar, I elaborated on chemical signatures of proton activities by means of operando characterization techniques. I am now writing a manuscript on this topic, in collaboration with other colleagues. Stay tuned!
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