Novel functional ceramics using anionic substitution in oxidic systems
Prof. Dr. R. Riedel (Div. Dispersive Solids)
Amorphous SiCN ceramics are well known for their high stability regarding corrosion and high temperatures. The inclusion of lithium into the SiCN matrix leads to a new ceramic material which was investigated as a solid state electrolyte in terms of its lithium ion conductivity.
SiCN/graphite composite materials are suitable for new lithium ion battery anodes due to better cycling behavior for the lithium intercalation compared with pure graphite, which is the common anode material for lithium ion batteries today. The main reason for the fatigue of this anodes is the exfoliation of the graphite.
The coating of active graphite particles with a physical and chemical inert material like amorphous SiCN ceramics leads to new composite materials which are able to prevent the exfoliation and minimize the irreversible capacity.
The electrochemical behavior could be tailored by using different precursors and by applying the process parameters like temperature, atmosphere etc. In situ deposition of graphite as well as nano silicium from the amorphous SiCN provide the focus of future investigations with the aim of creating materials with higher capacity and a better cycle behavior than graphite.