The invention provides a lithium-ion battery, a battery pack and an electric bus to solve the problem of a security risk of the lithium-ion battery in the prior art. The lithium-ion battery comprisesa shell, an electrolyte and a plurality of pole shanks, wherein the electrolyte and the pole shanks are packaged in the shell; a plurality of external short circuit components are also arranged in theshell; each external short circuit component comprises a positive short circuit connection sheet, a negative short circuit connection sheet and an insulating film; each insulating film is used for isolating each positive short circuit connection sheet from the corresponding negative short circuit connection sheet; the melting points of a membrane and each insulating film meet the expression as follows: Tm1-Tm2 is greater than or equal to 20 DEG C, wherein the Tm1 is the melting point of the membrane and the Tm2 is the melting point of each insulating film; and the heat shrinkage rate of eachinsulating film is greater than or equal to 20% when the heating temperature is 120-170 DEG C. According to the lithium-ion battery provided by the invention, the insulating films are subjected to heat shrinkage in advance to achieve the effect of ''external short circuit'' in thermal runaway, thereby effectively improving the security performance of the battery.