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High-voltage cathode materials have gained much attention as one of the promising electrode materials to increase power density of lithium ion batteries by raising the working voltage. However, the use of such high-voltage cathode materials is still challenging, because their working voltage is close to the electrochemical oxidation potential of organic electrolyte used in lithium ion batteries. In this work, we demonstrated that simultaneous fluorination of LiNi 0.5 Mn 1.5 O 4 (LNMO) particles as well as conductive agent in the electrode could significantly improve the electrochemical stability of LNMO cathode. The resulting electrode showed better cycle performance both at room temperature and elevated temperature compared to both bare LNMO electrode and the electrode with only LNMO fluorinated. These results showed that direct fluorination of high voltage cathode can reduce the side reaction of high voltage cathode electrode with the electrolyte, thereby stabilizing the surface of carbon black as well as that of high voltage cathode material.

Anode materials including graphite are known to be thermodynamically unstable toward organic solvents and salts and become covered by a passivating film (Solid electrolyte interphase, SEI) which retards the kinetics because of the high electronic resistivity. To achieve high performance in lithium ion batteries (LIBs), the SEIs are required to be mechanically stable during repeated cycling and possess highly ion-conductive. In this work, we have investigated an artificial pre-SEI on graphite electrode using a polymer binder containing lithium (i.e., a Li-copolymer of isobutylene and maleic anhydride, Li-PIMA) and its effect on the anode performances. During charging, the polymer binder with the functional group (–COOLi) acts as a SEI component, reducing the electrolyte decomposition and providing a stable passivating layer for the favorable penetration of lithium ions. Hence, by using the binder containing lithium, we have been able to obtain the first Coulombic efficiency of 84.2% (compared to 77.2% obtained using polyvinylidene fluoride as the binder) and a capacity retention of 99% after 100 cycles. The results of our study demonstrate that binder containing lithium we have used is a favorable candidate for the development of high-performance LIBs.

The effects of surface-modified carbon black induced by UV/ozone and triethylenetetramine on the microstructure and electrochemical properties of ink-jet-printed LiCoO 2 electrodes for lithium ion batteries are observed. The dispersion properties of surface-modified carbon black and LiCoO 2 ink are evaluated using particle size distribution measurements, surface pressure calculations, and scanning electron microscopy. Modifications to the surface of carbon black result in improved dispersion properties, which in turn enhance the compactness and homogeneity of the microstructure of ink-jet-printed LiCoO 2 electrodes compared to those printed with as-received carbon black. Electrochemical experiments indicate that LiCoO 2 electrodes ink-jet-printed with surface-modified carbon black exhibit improved initial specific discharge capacities compared to those printed with as-received carbon black due to the better electrical contact between the carbon black and the LiCoO 2 , as evidenced by the analysis of the area-specific impedance of the electrode as a function of the depth of discharge.