Rate-capability of (a) NaFeO2 [12], (b) NaFe0.5Co0.5O2, and (c) NaCoO2 in Na cells. The cells were charged to 4.0 V at a rate of 12 mA g− 1 and then discharged at different rates; 1/20 (12 mA g− 1)–30C (7260 mA g− 1). The sample loading on Al foil was (a) 1.3 (b) 2.4, and (c) 2.2 mg cm− 2 as the active material.
cells
charged
4.0 V
V
cells
rate
12 mA g− 1
mA g− 1
cells
rates
1/20 (12 mA g− 1)–30C (7260 mA g− 1)
mA g− 1
sample
(a) 1.3 (b) 2.4, and (c) 2.2 mg cm− 2
mg cm− 2