As stated above "when the battery goes off with a bang it produces Oxygen."
I suggest that those claiming that thermal runaway in Li-ion batteries produce oxygen in the off gasses would document the source of that claim.
"Lithium-Ion Batteries Hazard and Use Assessment" was published in July 2011 and was written by four professional and/or PhD engineers at Exponent Failure Analysis Associates, Inc. The report clearly states:
"No significant amount of oxygen is found in cell vent gases…, but plays no measurable role in the flammability of vent gases."
Details from the report on page 49: “ Exponent and others have measured cell case temperatures during thermal runaway reactions. For fully charged cells, these temperatures can reach in excess of 600°C (1,110°F); case temperatures for lithium-iron phosphate cells are generally lower. The temperature rise is driven by reactions of the electrodes with electrolyte and release of stored energy. Some cathode materials will decompose and may change their crystalline structure.This fact has led to a misconception that lithium-ion cells burn vigorously because they “produce their own oxygen.” This idea is incorrect. No significant amount of oxygen is found in cell vent gases.91 Any internal production of oxygen will affect cell internal reactivity,11 cell internal temperature, and cell case temperature, but plays no measurable role in the flammability of vent gases.
A footnote on the same page states: “Analysis of cell headspace gases can reveal the presence of argon, nitrogen, and oxygen consistent with cell construction conditions. In one instance (testing of a prototype cell), trace quantities of oxygen and hydrogen were measured in cell vent gases, but spark ignition testing of those gases did not result in ignition.”
Page 52 of the report also states: “Depending upon the environment around the cell, the cell vent gases may ignite. The gases are not “self-igniting.”27, 93 There must be sufficient oxygen in the surrounding environment to sustain combustion of hydrocarbons and there must be a competent ignition source to ignite the vent gases.”
The report offers multiple tables and data points demonstrating off gas compositions concentrations , including no oxygen, and various options for inerting the the thermal runaway off gases.
The report also describes various tests with cooling the thermal runaway.
Last edited by TacomaSailor; 30th Jan 2013 at 16:22.