SageBrush wrote: ↑
Tue Sep 01, 2020 4:11 pm
cwerdna wrote: ↑
Tue Sep 01, 2020 3:57 pm
Many folks have been pleading for GM to not ship future vehicles w/such slow DC FCing.
No kidding. It also strikes me as a very timid curve for a car with a liquid cooled battery.
I read this morning that the upcoming, new Gen "2021" Bolts to be released in a few months are expected to charge up to 200 kW. Call me skeptical, but 100 kW sustained up to 70% SoC would be most welcome and would do wonders for the car's utility and value.
I don't know the reason but I've heard the claims for the reason why Bolt's DC FC max rate is currently so slow is electrodes are too thick (example, search https://www.torquenews.com/8861/2020-ch ... ck-or-bust
https://www.energy.gov/sites/prod/files ... 202017.pdf
The U.S. Department of Energy (DOE) has a goal of reducing the production cost of a BEV battery to ultimately $80/kWh, increase the range of EVs to 300 miles, and decrease charge time to 15 minutes or less. In order to achieve this goal, a major effort within the battery research community has focused on increasing the energy density of the cell, which refers to the amount of energy stored in a specified weight or volume. Increasing electrode thickness is an effective way of improving the energy density of a cell.
However, thicker electrodes present several barriers to fast charging. As electrode thickness increases, charge times must also increase in order to avoid lithium plating. Lithium plating occurs when the charge rate exceeds the rate the lithium ions can intercalate into the crystal structure of the anode, which causes metallic lithium to form on the surface. Lithium plating can negatively affect performance of the electrode and lead to accelerated degradation of the battery, as well as impact cell safety. Therefore, it is thought that thinner electrodes are better suited for XFC applications, but this occurs with a tradeoff in increased battery cost. The analysis conducted in this report indicates that fast charge nearly doubles cell cost from $103/kWh to $196/kWh. The increase in cell cost is largely based on decreasing the anode thickness. Using thinner electrodes requires more cells to achieve the same energy density. Managing the heat generated in the battery during a charging event is also a potential barrier to XFC because temperatures in excess of 45°C will rapidly degrade battery lifetime.Higher temperatures can also introduce safety concerns as materials contained within the battery can begin to chemically and mechanically degrade.
I can't speak to what GM and LG Chem product planners had in mind in terms of goals, capabilities and tradeoffs (e.g. cost, density, safety, weight, manufacturing yields (i.e. what % of parts produces will be good vs. bad), etc.) I can only guess and base it upon the DC FC-capable cars and chargers that existed at the time + roadmap of the future wen they began planning and engineering work... From https://www.greencarreports.com/news/11 ... production
, it may have begun in 2011.
First delivery of Model S didn't happen until July 2012 and Supercharger network wasn't announced until a few months later.