Why Do Lithium-Ion Batteries Eventually Die? How To Improve The Lifespan...

Why Do Lithium-Ion Batteries Eventually Die? How To Improve The Lifespan
This video is absolutely fascinating, and it features a lecture by Professor Jeff Dahn from Dalhousie University on the subject of how to improve lithium-ion batteries. As I understand it, he has consulted Tesla on their battery technology, as well as other companies like GM. In this lecture he goes into great scientific detail on the variables that effect short and long-term charing capacity:

Professor Dahn's insight to an extent explains why Tesla recommends you only maintain the battery on a Model S at 80% capacity. It also explains why when you use a Tesla supercharger, why it quickly ramps up in charging miles per hour, then slows down once it hits around 80%. My takeaway point from this video and from my research suggests that Tesla has done a tremendous amount of research into understanding the variable that govern Lithium-Ion battery life.
Who exactly is Jeff Dahn? The following bio comes from his website:
Jeff Dahn is recognized as one of the pioneering developers of the lithium-ion battery that is now used worldwide in laptop computers and cell-phones.  Dahn's recent work has concentrated on the application of Combinatorial Materials Science methods to battery and fuel cell materials problems.  He is the author of over 500 refereed journal papers and co-inventor of 58 inventions with patents issued or filed.
Jeff Dahn was born in Bridgeport, Conn. in 1957 and emigrated with his family to Nova Scotia, Canada in 1970.  He obtained his B.Sc. in Physics from Dalhousie University (1978) and his Ph.D. from the University of British Columbia in 1982.  Dahn then worked at the National Research Council of Canada (82-85) and at Moli Energy Limited (85-90) before taking up a faculty position in the Physics Department at Simon Fraser University in 1990.  He returned to Dalhousie University in 1996.
Jeff Dahn has always interacted strongly with industry.  During his years at Simon Fraser University (90-96) he collaborated strongly with the R+D team at NEC/Moli Energy Canada (Now E-One/Moli Energy Canada).  Dr. Dahn took up the NSERC/3M Canada Industrial Research Chair in Materials for Advanced Batteries at Dalhousie University in 1996 and has held that position ever since.  Dahn is now collaborating with GM Canada, Magna E-Car, Medtronic Energy and Component Center, Nova Scotia Power and 3M in a 5-year project to develop longer lasting, lower cost Li-ion cells.
Jeff has received numerous awards including: International Battery Materials Association (IBA) Research Award (1995); Herzberg Medal, Canadian Association of Physicists (1996); ECS Battery Division Research Award (1996); Fellow of the Royal Society of Canada (2001);  Medal for Excellence in Teaching (2009) from the Canadian Assoc. of Physicists, The Rio-Tinto Alcan Award from the Canadian Institute of Chemistry (2010) and the ECS Battery Division Technology Award (2011).