High power, extended temperature range-capable, highly abuse overcharge and discharge tolerant rechargeable battery cell and pack

An electrochemical pouch cell comprising:

• a cathode, the cathode comprising a cathode electrochemically active polycrystalline material comprising the formula Li1+xMO2+y, wherein −0.9≤x≤0.3, −0.3≤y≤0.3, and wherein M comprises Ni at 80 atomic percent or higher relative to total M, wherein the cathode electrochemically active material includes a plurality of crystallites and a grain boundary between the plurality of crystallites, wherein the concentration of cobalt, aluminum, or both is higher in the grain boundary than in the center of the adjacent crystallites;
• two or more anodes comprising an anode electrochemically active material of the formula Li4+aTi5O12+b wherein −0.3≤a≤3.3, −0.3≤b≤0.3;
• wherein the anode and the cathode independently further comprise a PVdF binder intermixed with the anode electrochemically active material and the cathode electrochemically active material respectively;
• the anode and the cathode each independently further comprise a current collector substrate comprising aluminium, wherein the cathode current collector is coated with respective electrochemically active material on two sides;
• a porous polyolefin separator;
• an electrolyte comprising a lithium salt and a carbonate solvent;
• wherein the two or more anodes are terminal layers of a stack of electrodes;
• wherein an area ratio of anode to cathode is less than or equal to 1;
• and
• wherein a capacity ratio of anode to cathode is less than 1, and
• wherein the electrochemical cell is characterized by a substantially unchanged voltage to capacity profile following puncture by a blunt 2 mm diameter stainless steel nail at a speed of 1 cm/sec.