Spinel cathodes for Lithium Ion Batteries (LIB), such as LiCoMnO₄, offer higher operational voltages and higher energy densities than common LIB cathodes, like LiCoO₂ [1]. Compared to LiCoO₂ the energy density of a LiCoMnO₄ cathode is increased by 25%. Therefore, high voltage LIBs based on spinel cathodes are considered as possible candidates for future lithium battery technologies. However, commonly used liquid electrolytes are unstable at potentials above 4.5 V , which is the minimum operational voltage for spinel cathodes [2,3]. To access the full energy density of LiCoMnO₄ cathodes (~5.3 V) an all solid state approach is chosen by replacing the liquid electrolyte by a solid state electrolyte ceramic [4]. The processing of a cathode for an all solid state battery comes along with new requirements to the cathode material. Compared to common particulate based cathodes a different functional structure has to be developed to assure electronic and ionic diffusion paths. Additionally, it has to be compatible to the given solid electrolyte and – depending on the processing techniques – withstand higher temperatures during manufacturing. Lithium-manganese spinels in particular are known to be unstable at higher temperatures and tend to release lithium and oxygen from their lattice [5,6]. Therefore, sintering and stability studies for LiCoMnO₄ were carried out to find a processing route that leads to a high relative density without decomposition of the material. Additionally, different conceptual cathodes were tested and characterized structurally, microstructurally and regarding their electrical properties. The completion of this study finally leads to a cathode supported all solid state battery with lithium phosphorous oxy-nitride as solid electrolyte processed by physical vapour deposition.

References

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[2]  Goodenough JB, Kim Y. Chem. Mater. 2010;22:587–603.

[3]  Xu W, Chen X, Ding F, Xiao J, Wang D, Pan A, Zheng J et al. Journal of Power Sources 2012;213:304–16.

[4]  Li J, Ma C, Chi M, Liang C, Dudney NJ. Adv. Energy Mater. 2015;5:n/a-n/a.

[5]  Pasero D, Souza S de, Reeves N, West AR. J. Mater. Chem. 2005;15:4435–40.

[6]        Thackeray MM, Mansuetto MF, Dees DW, Vissers DR. Materials Research Bulletin 1996;31:133–40.