Metal-based very thin film anodes for lithium ion microbatteries

Revealing lithium–silicide phase transformations in nano-structured silicon-based lithium ion batteries via in situ NMR spectroscopy

“…Au (20 nm) colloids were dispersed on SS (cycled with a current rate of C/25, calculated based on a theoretical capacity of Li 3.75 Au, 451 mAh g À 1 ) 51 . The colloids have distinctive processes at 240 À 200 mV (namely, Au#d1) and 110-80 mV (Au#d2) on discharge, and 160 mV (Au#c1), 370 mV (Au#c2), and 450 mV (Au#c3) on charge, in good agreement with other studies 19,52,53 . A 50-nm-thick Au film on SS was also cycled with the same electrochemical schedule, which failed to charge in the 1st cycle, probably due to stresses from the Li x Au volume expansion in the film.…”

A Gold Micro-Reference Electrode for Impedance and Potential Measurements in Lithium Ion Batteries

“…The Li 3 Au phase is the most lithium-rich composition which can be obtained electrochemically, corresponding to a specific capacity of 408 mAh/g Au . 19,[22][23][24][25][26] The lithiation of gold proceeds in two main potential plateaus, with the first stage having an OCV potential of ∼0.3 V vs. Li/Li + , and the second ∼0.2 V vs. Li/Li + . 25 Surprisingly, the intermediate phases detected between α-Au and Li 3 Au during electrochemical alloying could not be assigned to any of the known thermodynamic Li-Au phases.…”

“…Despite its drawbacks as an anode, several properties of the lithium-gold alloy make it an interesting reference electrode material: i) the potentials of both stages are very flat, and already low degrees of lithiation will result in an OCV of around 0.31 V vs. Li/Li + ; ii) it is difficult to completely delithiate a lithium-gold alloy by electrochemical or chemical means; 24,26 iii) gold is chemically resistant against HF and does not form any substantial surface oxide films; 31 and, iv) the high electrical conductivity of gold means that the potential drop along the length of the reference electrode wire is negligible.…”

Alloy-Based Anode Materials

“…The galvanostatic charge-discharge curves obtained for such thin films of Au exhibit two voltage plateaus corresponding to the Li alloying process at 0.2 and 0.1 V, whereas Li removal from the alloy occurs in two steps at 0.18 and 0.4 V [152,153]. Mesoporous Au films show a better cycling stability than their compact thin film counterparts, with *16 % (at 80 mAh/g) of the original capacity retained after 30 charge-discharge cycles [154].…”

“…Although there are few literature papers on the electrochemical alloying of Au with Li at RT, Au thin films have been shown to accommodate Li in the 0.02-0.5 V potential range with a poor reversibility [152,153]. The galvanostatic charge-discharge curves obtained for such thin films of Au exhibit two voltage plateaus corresponding to the Li alloying process at 0.2 and 0.1 V, whereas Li removal from the alloy occurs in two steps at 0.18 and 0.4 V [152,153].…”