Stress effect on cycle properties of the silicon thin-film anode

Si thin-film electrodes were deposited by rf magnetron sputtering method, and stress variation during charge and discharge process was measured. When Si reacts with Li forming several alloy phases sequentially, large volume expansion occurs inducing compressive stress. On Li insertion to 0 V, the formation of Li4.4Si phase, which have a volume three or four times larger than Si, causes a microcracking in the electrode, thereby the cycle performance is deteriorated. However, by limiting the lower cut-off voltage to 0.1 V, the cyclability was improved significantly. This is attributed to the reduction of the crack formation due to volume expansion, as inferred from the stress variation profile.