Reducing Li-ion safety hazards through use of non-flammable solvents and recent work at Sandia National Laboratories

This article will briefly discuss the genesis of the Li-ion chemistry and its meteoric rise to prominence, supplanting aqueous rechargeable batteries such as NiCd and NiMH. The principal intent of this article is to discuss the issues with thermal instability of common Li-ion electrolytes, which detract from the positive attributes of this chemistry. The development of an innovative low-cost non-flammable electrolyte will greatly improve the safety and reliability of lithium batteries, a key technological hurdle that must be overcome for the wider application of this chemistry. This article will also include the advancements made in combating/mitigating solvent flammability through the addition of fire retardants, fluoro-solvents, ionic liquids etc. The scope of the article will be limited to the flammability of non-aqueous solvents and will not include the thermal instability issues of anodes and cathodes. We will elaborate using examples from our in-house research aimed at mitigating solvent flammability by using hydrofluoro ethers (HFEs) as a cosolvent. Additionally, we will describe in-house capabilities for prototyping 18,650 cells and in-house thermal abuse test capabilities that allow us to evaluate materials and their thermal responses in actual cell configurations.