In this study, we developed a doping technology capable of improving the electrochemical performance, including the rate capability and cycling stability, of P2-type Na 0.67 Fe 0.5 Mn 0.5 O 2 as a cathode material for sodium-ion batteries. Our approach involved using titanium as a doping element to partly substitute either Fe or Mn in Na 0.67 Fe 0.5 Mn 0.5 O 2 . The Ti-substituted Na 0.67 Fe 0.5 Mn 0.5 O 2 shows superior electrochemical properties compared to the pristine sample. We investigated the changes in the crystal structure, surface chemistry, and particle morphology caused by Ti doping and correlated these changes to the improved performance. The enhanced rate capability and cycling stability were attributed to the enlargement of the NaO 2 slab in the crystal structure because of Ti doping. This promoted Na-ion diffusion and prevented the phase transition from the P2 to the OP4/″Z″ structure.

LiNi 0.6 Co 0.2 Mn 0.2 O 2 (C622), a Ni-rich cathode material, was prepared and its durability tested in air and moisture. For the test, C622 was stored in a glovebox and in a humidity chamber at 50% RH. For each sample, the cell performance was tested in terms of the specific capacity, rate capability, and cycling stability; the changes in the crystal structure were also investigated. The results indicate that when C622 is stored in a humidity chamber, severe degradation occurs in all measurements relating to the cell performance, whereas when it is stored in a glovebox, no degradation is seen. This indicates that C622 is very sensitive to air and moisture. A larger quantity of residual lithium compounds, which are by-products of the reaction between the cathode material, CO 2 , and moisture in the air, could be seen on the surface of the C622 that was stored in a humidity chamber when compared to the one stored in a glovebox. The formation of residual lithium compounds and the corresponding changes in the crystal structure of C622 kept in the humidity chamber may be the reason for the degradation in the cell performance.

Flexible and wrinkle-free electrodes for lithium-ion batteries (LIBs) have been developed by using polyurethane as a binder. The electrodes provide LIBs with robust mechanical properties and good electrochemical performances along with MWNT.