RF-sputtered LiCoO2 thick films: microstructure and electrochemical performance as cathodes in aqueous and nonaqueous microbatteries

Evidence of Enhanced Ion Transport in Li‐Rich Silicate Intercalation Materials

“…Accurate measurements of Li‐ion diffusion coefficients for electrode materials are not straightforward and sometimes show significant scatter in values between different impedance studies. Nevertheless, experimental diffusion coefficients for Li 2 FeSiO 4 are found to be in the region of 10 −12 to 10 −11 cm 2 s −1 , which is consistent with our calculated value of 2 × 10 −12 cm 2 s −1 at 473 K. Although there are currently no measured diffusion data for direct comparison for the Li‐rich system, the magnitude is comparable to other cathode materials; for example, experimental diffusion coefficients of 10 −8 to 10 −11 cm 2 s −1 have been reported for Li + diffusion in oxide cathodes such as LiCoO 2 and Li(Ni,Mn,Co)O 2 . For the γ‐phase solid electrolyte Li 2.5 Zn 0.75 GeO 4 , Fujimura et al have calculated a D Li of about 10 −9 cm 2 s −1 at 500 K, which is in good agreement with our data for a similar LISICON structure.…”

“…It is worth noting that similar cooperative mechanisms have been discussed in connection with interstitial lithium migration and defect cluster models in a group of solid electrolytes known as the gamma phases, of which Li 2+2 x Zn 1− x GeO 4 (LISICON), Li 3+ x Ge x V 1− x O 4 and Li 3 PO 4 are members, but have not been widely examined in Li‐rich electrode materials.…”

Unusual Mn coordination and redox chemistry in the high capacity borate cathode Li7Mn(BO3)3

“…However, the calculated D Li value, of the order of 10 À9 cm 2 s À1 at 325 K, is in agreement with other electrode materials, such as the conventional cathode LiCoO 2 and its solid solution derivative Li(Ni,Mn,Co)O 2 , for which experimental lithium diffusion coefficients between 10 À11 and 10 À8 cm 2 s À1 have been reported for comparable temperatures. [67][68][69][70] The data is presented as an Arrhenius plot (ln D vs. 1/T ) in Fig. 4, from which an estimation of the migration activation energy (E act ) can be derived.…”

Sputtered LiCoO2 Cathode Materials for All-Solid-State Thin-Film Lithium Microbatteries

“…Such films exhibited the specific capacity of 27 µAh cm −2 µm −1 at a current density of 50 µA cm −1 after 150 cycles with an average capacity decrease rate of 0.05% per cycle. Jeevan-Kumar et al [73] produced LCO thin films (1.8 µm thick) from a Li-enriched (10%) sintered 3-in LiCoO 2 target to compensate the volatility of Li. These films deposited on metallized Si substrate kept at T s = 250 °C with subsequent annealing at 650 °C under an oxygen pressure of 5 Pa showed a well-oriented HT-LiCoO 2 phase with predominant (104) planes.…”