from chemistry to pack
Every solid-state chemistry roundup mentions that cells need “stack pressure,” usually as a single line in a spec table. What that line means for the person actually designing the pack around the cell: This gets skipped almost everywhere. This is the pack-design follow-on to our cell-level piece on What’s the right stack pressure?, which covers … Read more
Author Dr. Simon Madgwick of Nuvvon Inc. Nuvvon recently showed their solid state 5Ah SiC NMC cell cycling continuously at 3C/5C for 1000 cycles full DOD to 90% SOC. Then incredible sub-zero temperature performance discharging down to -50°C with over 50% capacity and charging at -40°C. Here is the final post on these 5Ah Silicon cells – comparing … Read more
Quick facts The prompt for this piece Prof Louis Piper (WMG/Warwick, Faraday Institution) posted a summary of this paper on LinkedIn, describing work from the Faraday Institution’s LEAP project led by Eleni Fiamegkou and Daniela Proprentner. His framing of the result is worth repeating directly, because it’s the thesis the underlying data set out to … Read more
A new Nature Energy paper puts a number on it I’ve written before about cell electrode pressure and how it’s applied and lost across a module’s life, and about the practical business of mapping pressure distribution across a pouch cell in operando. Both of those pieces stopped short of answering the question every pack designer … Read more
The Current Interrupt Device CID activation pressure is important to understand as this will be the internal cell pressure at which the electrical connection will be opened. Hence the cell will then be electrically disconnected from the external circuit. The pressure increase inside the cell is due to gas formation caused by decomposition reactions which … Read more
The LFP cell clamping pressure is important as it keeps the active layers in contact. However, we have to remember that LFP cells expand over their lifetime by 10 to 20% in thickness and during charge / discharge they expand / contract respectively. Hence there is an irreversible and reversible aspect to cell expansion. Here … Read more
CompreCell Pouch x TekScan Sensor Author: rhd instruments GmbH & Co. KG Post based on an application note for which that and a full summary are now available: rhd-instruments.de magazine Introduction The pressure applied to pouch cell batteries is key to their performance and cycle life [1, 2, 3, 4]. One of two modes of … Read more
Gases are generated in the cathode, anode and electrolyte during the formation and cycling of a battery cell. As this is a closed system the result is a cell gas pressure. What this gas is composed of, how it behaves and how it changes with State of Charge (SoC) and the cycling of the cell … Read more
As you charge a cell it expands, when you discharge a cell it contracts and as the cell ages over its lifetime we see a continuing cell expansion. Thus the cell expansion can be divided into: The reversible cell expansion comes from changes in graphite layer spacing associated with different graphite-lithium intercalation compounds induce reversible … Read more
The cell electrode pressure is required to keep the cell operating at it’s peak performance over it’s lifetime. However, is there an optimum pressure and why exactly does the cell need it? As the cell is charged lithium ions move into the graphite anode and the cell will increase in thickness. Silicon in the anode … Read more