With accelerated electrification of the society, development of stationary energy storage systems is critical to successfully utilize renewable energy sources. Behind-the-meter storage (BTMS) systems allow the users to generate energy on-site (e.g., through solar panels), store, and use as needed to effectively lower the demand charge and minimize the grid impacts. Among various lithium (Li)-ion battery chemistries, lithium titanate (Li₄Ti₅O₁₂, LTO) anode and lithium manganese oxide (LiMn₂O₄, LMO) cathode pair provide safe, critical material free, long lifetime batteries meeting the key requirements for BTMS applications. However, the LTO/LMO chemistry has been traditionally used as a high power cell due to their low energy density resulting from low specific capacity of the active materials and high operating potential of LTO. While the cell voltage is thermodynamically fixed, the cell capacity can be increased by increasing the active material portion within the cell, which can be achieved by using thicker electrodes.

Here, we examine LTO/LMO cells with electrode loadings greater than 3 mAh/cm² toward developing high energy density LTO/LMO batteries. We also evaluate different negative-to-positive (N/P) ratios to maximize the energy density and cycle life. Since LTO operates at a potential that is well above the Li redox potential, Li plating is not a concern and the anode does not need to be oversized. For example, N/P ratio can be set to 1 to maximize the energy density, or the cathode can have a higher loading (N/P<1) to increase the Li inventory. In addition, we examine different electrolyte formulations factoring in safety. For example, electrolytes without flammable linear carbonates are tested with various electrode thickness and N/P ratios. Combining the electrode, electrolyte, and cell designs, we demonstrate how the LTO/LMO power chemistry can be converted to energy cells with enhanced cycle life.