Li dendrite formed in Li metal batteries can be categorized into two different types. One is the detrimental Li dendrite that heads towards the separator with a potential to short cell. The other is the ill-defined fibrous Li formed within bulk Li metal. The detrimental Li dendrite may cause cell short, while the other dendrites, covered by SEI, mainly increase cell impedance and terminate the cell operation, most often, before any “short” really happens. Without decoupling these two different Li dendrites, it is hard to develop any effective approach to realize both stable and safe Li metal batteries. Herein, a straightforward approach is proposed to induce the growth of detrimental dendritic Li so the cells are “shorted” frequently and consistently. Based on this new protocol, various electrolytes are revisited and the SEI derived are compared and quantified, providing new insights for addressing the challenges in rechargeable Li metal battery technologies.