Electrode piece, cell and energy storage device

An electrode piece for forming a cell, comprising:

• a current collector;
• a diaphragm arranged on the surface of the current collector;
• and
• a groove, the bottom of the groove being an exposed portion of the current collector and the peripheral sides of the groove being the diaphragm;
• wherein,
• the exposed portion of the current collector at the bottom of the groove is a blank current collector, and the blank current collector is formed with a connecting portion;
• the connecting portion is cut out from the blank current collector as a part of the blank current collector and bent on the blank current collector along a width direction of the electrode piece;
• and a first portion of the connecting portion extends beyond an outer edge of the current collector in the width direction,
• wherein the groove is formed by the exposed portion of the current collector and two diaphragm sidewalls in the width direction, wherein a second section of the connecting portion disposed in the groove in the width direction is surrounded by the blank current collector and the two diaphragm sidewalls;
• a plurality of the connecting portions of the electrode piece are fixed together to form an electrode tab of the cell;
• or the connecting portions of the plurality of the electrode pieces are fixed together to form the electrode tab of the cell, wherein the second portion of the connecting portion is in contact with the blank current collector and the second portion is fixedly connected to the blank current collector.