An energy storage apparatus , whereby the energy storage apparatus is a single battery , comprising a battery end cover assembly , the battery end cover assembly comprising: an end cover of a rectangle; terminal assemblies , the terminal assemblies being connected to the end cover ; and a pressure relief mechanism , the pressure relief mechanism being disposed on the end cover , and the pressure relief mechanism and the terminal assemblies being distributed at intervals in the length direction of the end cover ; wherein the area of a figure formed by an outer contour of the end cover is a first area S1, the area of a projection of the pressure relief mechanism on the end cover is a second area S2, and the second area S2 accounts for 0.5% to 5% of the first area S1; the size of the pressure relief mechanism in the length direction of the end cover is b1, and b1 accounts for 5% to 12% of the length b0 of the end cover ; and the size of the pressure relief mechanism in the width direction of the end cover is e1, and e1 accounts for 15% to 25% of the width e0 of the end cover ; wherein the pressure relief mechanism comprises an anti-explosion valve , and the anti-explosion valve comprises a preset opening area ; the anti-explosion valve is provided with a notch groove , and the notch groove is located in the preset opening area ; the minimum thickness of the anti-explosion valve on the position of the notch groove is a first thickness n1, the thickness of the anti-explosion valve on the position of the preset opening area is a second thickness n2, and the first thickness n1 accounts for 15% to 25% of the second thickness n2; the tensile strength of the anti-explosion valve is 90-130 N/mm 2 ; an area of the preset opening area is at least a half of the second area S2 and not more than 95% of the second area S2; and a ratio (a/S2) of a capacity a of the energy storage apparatus to the second area (S2) is at least equal to 1.8, wherein the unit of the capacity a is ampere-hour (AH), and the unit of the second area S2 is mm 2 . an end cover of a rectangle; terminal assemblies , the terminal assemblies being connected to the end cover ; and a pressure relief mechanism , the pressure relief mechanism being disposed on the end cover , and the pressure relief mechanism and the terminal assemblies being distributed at intervals in the length direction of the end cover ; wherein the area of a figure formed by an outer contour of the end cover is a first area S1, the area of a projection of the pressure relief mechanism on the end cover is a second area S2, and the second area S2 accounts for 0.5% to 5% of the first area S1; the size of the pressure relief mechanism in the length direction of the end cover is b1, and b1 accounts for 5% to 12% of the length b0 of the end cover ; and the size of the pressure relief mechanism in the width direction of the end cover is e1, and e1 accounts for 15% to 25% of the width e0 of the end cover ; wherein the pressure relief mechanism comprises an anti-explosion valve , and the anti-explosion valve comprises a preset opening area ; the anti-explosion valve is provided with a notch groove , and the notch groove is located in the preset opening area ; the minimum thickness of the anti-explosion valve on the position of the notch groove is a first thickness n1, the thickness of the anti-explosion valve on the position of the preset opening area is a second thickness n2, and the first thickness n1 accounts for 15% to 25% of the second thickness n2; the tensile strength of the anti-explosion valve is 90-130 N/mm 2 ; an area of the preset opening area is at least a half of the second area S2 and not more than 95% of the second area S2; and a ratio (a/S2) of a capacity a of the energy storage apparatus to the second area (S2) is at least equal to 1.8, wherein the unit of the capacity a is ampere-hour (AH), and the unit of the second area S2 is mm 2 . <EOS>