Rachid Yazami (Arabic: رشيد اليزمي ; born 1953) is a Moroccan scientist, engineer, and inventor. He is best known for his critical role in the development of the graphite anode (negative pole) for lithium-ion batteries and his research on fluoride ion batteries.
Education Yazami graduated from the Grenoble Institute of Technology in 1978. He also received a PhD degree in 1985.
Battery research Yazami's research project included a study of graphite intercalation compounds for lithium battery applications. In 1985, he joined the French National Centre for Scientific Research (CNRS) as a research associate. He was later promoted to the position of research director and professor in 1998. In 1980, Yazami was the first scientist to establish the reversible intercalation of lithium into graphite in an electrochemical cell using a polymer electrolyte. Eventually, his discovery led to the lithium-graphite anode which is now used in commercial lithium-ion batteries, a product with over $80 billion in market value. Yazami also worked on other forms of graphite materials for cathode applications in lithium batteries, including graphite oxide and graphite fluoride. In 2007, he founded a start-up company in California to develop and commercialize his patented discoveries, particularly on fluoride ion batteries (FIBs). While holding a research director position with the CNRS in France, Yazami served as a visiting associate at the California Institute of Technology between 2000 and 2010. There, he conducted cooperative research on electrode materials, including nanostructured materials like carbon nanotubes, nano-silicon, and nano-germanium anodes. His research on cathode materials included thermodynamics studies of phase transitions in lithiated transition metal oxides and phosphates. He also developed a new electrochemical technique based on thermodynamics measurements (ETM), which can be applied to assessing a battery's state of charge, state of health, and state of safety. Entropymetery applications include battery life extension owing to adaptive (smart) battery charging protocols and battery safety enhancement. In 2010, Yazami was appointed a Nanyang Visiting Professor. He was promoted in 2012 to the Cheng Tsang Man Chair Professor in Energy at the School of Materials Science and Engineering of the Nanyang Technological University (NTU) in Singapore. He served as the Director of Battery Programs at the Energy Research Institute (ERIAN) and as a Co-Principal Investigator in TUM Create Center of Electromobility lab. until 2017-18. While in Singapore, Yazami co-authored over 200 publications in peer-reviewed journals, in proceedings of international meetings, and as book chapters. He is the inventor involved in close to 180 patents according to the WIPO site. From his recent experimental work, Yazami theorized that in a sealed rechargeable battery cell (closed system), such as a lithium-ion battery, two different states of charge of the battery cannot simultaneously share the same entropy and the same enthalpy values, a statement referred to as the "Yazami's Battery Theorem." The theorem can be expressed as: (∆S(x1)=∆S(x2)) and (∆H(x1)=∆H(x2))⇔ x1=x2 , where x1, x2 are two states of charge, ∆S= entropy, ∆H= enthalpy In fact, Yazami established a more universal (empirical) law that applies to primary and rechargeable batteries, that is the state of charge is a linear function of entropy and enthalpy. SOC=α+β∆S+γ∆H, in which α, β and γ coefficients depend on the cell' chemistry and state of health. This equation is reminiscent of Gibbs free energy. Yazami also developed a new method based on entropymetry to detect an early stage of an internal short circuit within a battery cell, therefore making batteries safer. An internal short is the main root cause of a battery undergoing a thermal runaway involving fume, fire and explosion. More recently, Yazami invented a new method enabling ultra-fast charging (UFC) lithium ion batteries in 10 minutes and below. The method was coined by him as "Non-linear voltammetry" (NLV). UFC is critical for rapid deployment of electric vehicles.
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