What do lithium batteries and electrochemical research have to do with Boeing and the Dreamliner 787? Possibly everything – as you recall the current status of the magnificent Boeing Dreamliner is grounded. This seems largely due to issues with the lithium-ion batteries designed into them. The brilliant research paper by Purdue’s David R. Ely and R. Edwin Garcia gives insight/s into the possible issues of “dendrite formation”. This information was released yesterday, March 5, 2013 by the Purdue newsroom. The paper goes by the otherwise obscure title of “Heterogeneous Nucleation and Growth of Lithium Electrodeposits on Negative Electrodes”.
As far as we know, some training in electrochemistry is still required in chemistry college majors. The terms in the paper on the topic are otherwise challenging. The latest research is available through the link provided by the Purdue press release. Dendrites – and their growth – appear to be the main source of trouble and failure in lithium-ion batteries. Did your camera battery recently go dead? That could be the problem. And the FAA issued an emergency directive to look into the problem of lithium–ion battery failures on the troubled Dreamliner. Some days ago the Federal Register reported that the directive is now part of the US code of law.
Back to the research paper, the scientific research appears to have described some solid scientific fundamentals on the causes of these battery failures. The typical battery contains an anode and a cathode – a breach between these points of contact will cause a “short”. Thus lithium (in an electrolyte solution of a battery) will nucleate on the anode and grow. The growth can be “spike-like” or “massive” and can continue until it reaches the cathode. This can result even in the presence of a polymeric barrier. In the case of the 787 batteries, it seems that this is the likely cause of potentially rapid discharge. The supposed discharges may have been so rapid that they may have caused the battery fluid to heat to the point of incinerating the battery.
The research has theorized five possible periods (or “regimes”) of the currently undesired growth of lithium dendrites in the battery. Possible damage from the periods of potential growth are thought to be controlled by specific engineering of the anode surface roughness arising from particulate architecture. Further control of the anode comes from plating it, “life cycle/s” and “wetting”. For more on the Dreamliner issue see our blog post.