from chemistry to pack
Jerry Wan’s post (right) asks whether cell design has a “golden ratio” for aspect ratio. He concludes that there isn’t a universal one, and that’s right. But the reasons are worth working through, because the best shape changes completely depending on where the tabs are and which edge the heat leaves by. A ratio that … Read more
Single side busbars give you some advantages in designing cylindrical cells, but we have always known there is a resistance increase. Single Side 21700 Busbars If we look at the section through the cylindrical cell we see that the main can of the cell is the negative electrode. This can gets crimped onto the top-cap … Read more
AION Engineering INC When you open the datasheet of a lithium-ion cell, one of the first values to catch your eye is the internal resistance. Typically, it sits there as a single, proud number: ACIR: 15 mOhm. Many engineers look at this number, validate the “quality” of the cell, and integrate it into their vehicle … Read more
AION Engineering INC In lithium‑ion battery design, internal resistance is one of the most critical parameters governing power capability, heat generation, fast‑charge performance, and overall efficiency. The difference in internal resistance between wound (spiral/jelly‑roll) cells and Z‑stack (stacked) cells is often misunderstood as a chemistry issue, while in reality it is largely a current‑path and … Read more
AION Engineering INC Why High Porosity Can Lower Resistance in Power Cells Introduction Area Specific Resistance (ASR) is one of the most important performance indicators in lithium ion cathodes. Engineers often assume that reducing porosity improves conductivity and therefore lowers ASR. This idea comes from the expectation that a denser structure provides better particle contact … Read more
In the battery application world everyone is always looking for power vs energy density. Wanting the maximum of both. However, as we know from a comparison of power vs energy cell design it is nearly impossible to have both. In simple terms the energy cell has thicker layers of active material, thinner current collectors and … Read more
For most simple peak power calculations we will be interested in the Direct Current Internal Resistance (DCIR) value for a new cell at 50% SOC (25°C, 10s), Open Circuit Voltage (OCV) and minimum voltage. Note: this is just an estimation and this needs to be compared to the manufacturers specifications and tested values. However, as … Read more
Cylindrical lithium-ion cells have long used metal tabs to connect the current collectors to the terminals. These tabs act as the path for current to flow out of the electrode layers and into the external circuit. While this design has been reliable for decades, it introduces a few well-known limitations, particularly for high power applications. … Read more
AION Engineering INC Correct management of performance parameters in lithium-ion cell technology plays a critical role in energy storage and fast discharge processes. DCIR represents the internal resistance of the cell under DC current. Therefore, how much the cell will heat up during discharge depends on the current drawn and the DCIR value. The heating … Read more
The Ampace JP40 is a tabless 21700 cylindrical format cell designed to deliver high current discharge. Metrics A significant improvement in performance is achieved with the tabless design. The manufacturing video appears to show the ends of the jelly roll being bent over by an anvil that quickly comes in and punches the roll end … Read more