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LiFePO 4 (LFP) primary particles and secondary agglomerates have been processed into water-and solvent-based cathodes. By means of neutron and X-ray diffraction it was found that no structural changes of LiFePO 4 occurred upon water-and solvent-based slurry preparation. Electrochemical characterization was carried out with full-cells and a distinct influence of particle morphology was observable. Water-based processing of primary particles leads to deficits in electrochemical performance while secondary agglomerates are non-sensitive to water during processing. In the presence of water, high mechanical stress during slurry preparation causes a partial detachment of carbon coating. However, this effect is negligible for secondary agglomerates since only surface particles are exposed to mechanical stress. Due to longer diffusion paths and the fact that secondary agglomerates represent a micro-heterogeneity in the cathode, the C-rate capability of secondary agglomerates is slightly lower than that of primary particles. This paper demonstrates that for any high energy application with moderate C-rates, secondary agglomerates hold a great potential for environmentally friendly and cost-efficient water-based cathode production.

Polyphosphazene based polymer electrolytes exhibit excellent thermal and electrochemical properties accompanied by a high stability versus lithium metal anodes [1]. The combination of the cross-linked polymer matrix with electrolytes based on organic carbonates or ionic liquids leads to ionic conductivities of 1 mS/cm at 30 °C and good lithium transference numbers. Even with high amounts of liquid additives, the mechanical stability is suitable for use as ion conducting polymeric separator membrane for lithium ion cells. Here, we present the electrochemical performance of different “MEEP” based gel polymer elecrolytes and the galvanostatic cycling behaviour using cells with lithium metal anodes (cf. Fig. 1) and different cathode materials. The results indicate a very good cycling stability due to the high stability of the polymer in contact with metallic lithium. Compared to other gel polymer electrolytes in combination with carbon anodes [2] the “MEEP” based gel polymers exhibit good cycling stability with higher specific capacities. Fig. 1. Galvanostatic cycling of a full cell with polymeric gel electrolyte from MEEP using LiFePO4cathode and metallic lithium as anode. The authors acknowledge funding by the German Ministery for education and research (BMBF) within the project “MEET Hi-EnD“. [1] Jankowsky S. et al., J. Power Sources 2014, 253, 256-262. [2] Isken P. et al., J. Power Sources 2013, 225, 157-162.