Journal of The Electrochemical Society · 1997 · 1.4K citations · 0 references
Natural SciencesMaterials EngineeringMaterials ScienceElectrochemical EngineeringInorganic ChemistryMaterials ChemistryAlloysBattery MaterialsElectrode MaterialsEnergy Storage MaterialsX-ray CrystallographyX-ray DiffractionAmorphous Matrix FormationCoin Cell BatteriesDischarge ProcessesIn Situ X-ray DiffractionLithium-ion Battery Cathode MaterialsLithium-ion Battery Electrodes Based On Metal OxidesLithium-ion Battery MaterialsTin Oxides
The study employs electrochemical and in situ X‑ray diffraction on tin‑oxide cathodes in Li‑ion coin cells, revealing that oxygen from the oxide irreversibly bonds with lithium to form an amorphous lithia matrix that maintains electrode connectivity during Li‑Sn alloying. The materials achieve ~1000 mAh g⁻¹ Sn discharge capacities but suffer 200–700 mAh g⁻¹ irreversible losses, and XRD shows that lithium insertion forms Li‑Sn alloys while the original oxide does not recover upon delithiation, leaving metallic Sn mixed with amorphous Li‑O.
We report our electrochemical and in situ x‐ray diffraction experiments on a variety of tin oxide based compounds; SnO, , , and glass, as cathodes opposite lithium metal in a rechargeable Li‐ion coin cell. These materials demonstrate discharge capacities on the order of 1000 mAh/(g Sn), which is consistent with the alloying capacity limit of 4.4 Li atoms per Sn atom, or 991 mAh/(g Sn). These materials also demonstrate significant irreversible capacities ranging from 200 mAh/(g active) to 700 mAh/(g active). In situ x‐ray diffraction experiments on these materials show that by introducing lithium, lithium oxide and tin form first, which is then followed by the formation of the various Li‐Sn alloy phases. When lithium is removed the original material does not reform. The ending composition is metallic tin, presumably mixed with amorphous lithium oxide. The oxygen from the tin oxide in the starting material bonds irreversibly with lithium to form an amorphous matrix. The Li‐Sn alloying process is quite reversible; perhaps due to the formation of this lithia "matrix" which helps to keep the electrode particles mechanically connected together.