| When Sn-rich electrodes are cycled in a Li cell to large voltages (>1.4 V) anomalous high-voltage irreversible capacity (AHVIC) can be initiated. AHVIC is detrimental to the cell and should be avoided. A theory describing AHVIC is proposed that teaches ways to eliminate AHVIC. Three ways to avoid AHVIC are: (1) keep the recharge voltage below 1.3 V (vs. Li); (2) cycle the cell at a rate above about 75 mA/cm2 and (3) by alloying Sn with another element (such as Cu).; It is shown that advanced negative electrode materials for Li-ion batteries can be made quickly, simply and inexpensively using electrodeposition. In order to investigate a wide range of alloys in a single experiment, combinatorial electrodeposition has been successfully developed and implemented. Electrodes are cut from the composition spread film and tested in Li button cells to determine which composition exhibits both high capacity and good capacity retention. Using combinatorial methods it was determined that a Cu-Sn electrode with 28 atm. % Sn satisfied these criteria.; Combinatorial electrodeposition can be applied to many binary systems. Here we look at three binary systems: Cu-Sn, Cu-Zn and Sn-Zn. Composition-spread films were deposited for each system. Composition and crystal structure varied smoothly with position for each system. Combinatorial electrodeposition can also be applied to ternary systems. The Cu-Sn-Zn system is discussed as an example.; Combinatorial electrodeposition embodies and even extends the advantages of combinatorial material science: faster, cheaper, better, simpler and scalable. Ingenuity replaces robots and million dollar machines with water guns and buckets. |
