3 Search Results

Li₃BN₂ is investigated for the first time as a transition metal free, high capacity cathode material for Li-ion batteries. It is shown that α-Li₃BN₂ can exhibit a specific capacity of 890 mA h g^-1 with the charge storage mechanism associated with the valence state change of N ions in the BN₂ anion. The particular capacity demonstrated in this study is the highest one ever reported in literature for an intercalation-type cathode material. Moreover, using the valence state change of N ions as a charge storage mechanism opens the door for designing additional high performance, transition metal free electrodes in themore » future.« less

We introduce a new concept of hybrid Na-based flow batteries (HNFBs) with a molten Na alloy anode in conjunction with a flowing catholyte separated by a solid Na-ion exchange membrane for grid-scale energy storage. Such HNFBs can operate at ambient temperature, allow catholytes to have multiple electron transfer redox reactions per active ion, offer wide selection of catholyte chemistries with multiple active ions to couple with the highly negative Na alloy anode, and enable the use of both aqueous and non-aqueous catholytes. Further, the molten Na alloy anode permits the decoupled design of power and energy since a large volumemore » of the molten Na alloy can be used with a limited ion-exchange membrane size. In this proof-of-concept study, the feasibility of multielectron transfer redox reactions per active ion and multiple active ions for catholytes has been demonstrated. Furthermore, the critical barriers to mature this new HNFBs have also been explored.« less

Using high-energy ball milling of the Li₂S plus carbon black mixture followed by carbonization of pyrrole, we have established a facile approach to synthesize Li₂S-plus-C composite particles of average size 400 nm, encapsulated by a nitrogen-doped carbon shell. Such an engineered core–shell structure exhibits an ultrahigh initial discharge specific capacity (1029 mAh/g), reaching 88% of the theoretical capacity (1,166 mAh/g of Li₂S) and thus offering the highest utilization of Li₂S in the cathode among all of the reported works for the encapsulated Li₂S cathodes. This Li₂S/C composite core with a nitrogen-doped carbon shell can still retain 652 mAh/g after prolongedmore » 100 cycles. These superior properties are attributed to the nitrogen-doped carbon shell that can improve the conductivity to enhance the utilization of Li₂S in the cathode. As a result, fine particle sizes and the presence of carbon black within the Li₂S core may also play a role in high utilization of Li₂S in the cathode.« less