High-Voltage Electrolytes Based on Adiponitrile for Li-Ion Batteries

Adiponitrile, CN[CH2]4CN, ADN, was evaluated as both a solvent and cosolvent in safer and more electrochemically stable electrolytes suitable for high energy and power density Li-ion batteries. An electrochemical investigation of its electrolyte solution with the Li(CF3SO2)2N, LiTFSI, salt showed a wide electrochemical window of 6 V vs Li+/Li. The high melting point and the incompatibility of ADN with graphite anode required the use of ethylene carbonate (EC) as a cosolvent. The resultant EC:ADN electrolyte solutions showed ionic conductivities reaching 3.4 mS/cm, viscosities of 9.2 cP, and an improved resistance to aluminum corrosion up to 4.4 V, all at 20\ub0C. Li-ion batteries incorporating graphite/LiCoO2 electrodes were assembled using EC:ADN electrolyte mixture containing 1 M LiTFSI and 0.1 M LiBOB as a cosalt, and discharge capacities of 108 mAh/g with very good capacity retention were obtained. AC impedance spectra of the batteries recorded as a function of charging and cycling indicated the presence of a stable solid electrolyte interface.On a \ue9valu\ue9 l\u2019adiponitrile, CN[CH2]4CN (ADN), en tant que solvant ou cosolvant pour des \ue9lectrolytes plus s\ue9curitaires et plus stables sur le plan \ue9lectrochimique, convenant \ue0 des piles Li/ion \ue0 haute \ue9nergie et haute densit\ue9 de puissance. Une \ue9tude \ue9lectrochimique de sa solution \ue9lectrolyte avec le sel Li(CF3SO2)2N, LiTFSI, a permis de mettre en \ue9vidence une large fen\ueatre \ue9lectrochimique de 6 V par rapport \ue0 Li+/Li. Le point d\u2019\ue9bullition \ue9lev\ue9 et l\u2019incompatibilit\ue9 de l\u2019ADN avec l\u2019anode en graphite ont rendu n\ue9cessaire l\u2019utilisation de carbonate d\u2019\ue9thyl\ue8ne (CE) comme cosolvant. Les solutions \ue9lectrolytes CE/ADN ont exhib\ue9 des conductivit\ue9s ioniques pouvant atteindre 3,4 mS/cm, des viscosit\ue9s de 9,2 cP et une meilleure r\ue9sistance \ue0 la corrosion de l\u2019aluminium jusqu\u2019\ue0 4,4 V, le tout \ue0 20 \ub0C. On a assembl\ue9 des piles Li/ion comportant des \ue9lectrodes graphite/LiCoO2 et un m\ue9lange \ue9lectrolyte CE/ADN contenant du LiTFSI 1 M et du LiBOB 0,1 M en tant que co-sels, qui ont exhib\ue9 des capacit\ue9s de d\ue9charge de 108 mAh/g avec une tr\ue8s bonne r\ue9tention de capacit\ue9. Le spectre d\u2019imp\ue9dance c.a. des piles enregistr\ue9 en fonction de la charge et du cycle a mis en \ue9vidence la pr\ue9sence d\u2019une interface \ue9lectrolyte solide stable.Peer reviewed: YesNRC publication: Ye