The Powerhouse: Inside the Invention of a Battery to Save the World by Steve LeVine Read Free Book Online Page B

saw an Argonne man with a sign. Greeting the family, he bestowed a silver dollar on each of the daughters. The gesture swept aside Lisa’s apprehensions about life in a new country.
    Work started at once. Thackeray adopted Chris Johnson as a protégé and took him along to an international lithium battery conference in Boston. Arriving there, Johnson watched as a slew of scientists greeted Thackeray in the hotel lobby. “Everyone knew Mike,” Johnson said. “Everyone was coming up to him. ‘How are you doing? I understand you are at Argonne now.’ I am thinking, ‘Wow, he is really major in the field. And this is going to be a really nice relationship.’”
    Thackeray began to brief Johnson about his plan. If you reduced the amount of expensive cobalt in the cathode and substituted plentiful manganese in its place, you could make batteries that were both cheaper and safer than Goodenough’s industry-standard chemistry. But you could only use so much manganese because it tended to degrade over time and destroy the battery’s performance. Instead, you needed to deploy it together with nickel, which preserved the manganese and hindered its degradation. That made the ideal compound a combination of nickel, manganese, and cobalt, or NMC, coupled of course with lithium.
    Yet while this formulation was striking, it did not break new ground. The problem was that physics stepped in and spoiled Thackeray’s picture. Nickel, manganese, and cobalt, it turned out, would come apart just like Goodenough’s formulation if you sent too much lithium into the shuttling motion between electrodes that created electricity.
    Thackeray thought back to South Africa. He had learned that a compound of lithium, manganese, and oxygen that went by the atomic lettering Li 2 MnO 3 was electrochemically inactive. It was normally cast aside as an impurity. But now Thackeray’s intuition told him the story was incomplete—he thought there could be more to the material than anyone knew. His idea was to add a bit of Li 2 MnO 3 to the lithium-laced NMC. Thackeray suspected that this twist would buttress the NMC and keep the cathode intact as the battery was charged and discharged.
    In 1994 and 1995, Johnson created test battery cells using the formulation that Thackeray described and intercalated the lithium. He found that he was able to shuttle well over half the lithium between the two electrodes, all while the NMC structure held very much together. It was as though the cathode had been waiting for the Li 2 MnO 3 to provide it stability.
    Johnson learned why Thackeray’s intuition was correct. Even though the Li 2 MnO 3 was itself inactive when introduced into a cathode, its manganese and lithium went on to migrate and lodge in the NMC like pillars. These atoms propped up the structure while the lithium in the NMC began to shuttle.
    Visually, both NMC and Li 2 MnO 3 resemble a stripped-down house. The floor and ceiling are made of oxygen atoms, and the walls comprise nickel, cobalt, and manganese. Scientists call this framework a lattice. Because the lattices of the NMC and the Li 2 MnO 3 are similar, Johnson could easily integrate the two at the nanoscale.
    If the only notable thing was that the compound now held together, Johnson would have been engaged in a mere thought exercise. But stability wasn’t their only success. If you were thinking about an electric car, the NMC led to a better cathode than Goodenough’s lithium-cobalt-oxide, his lithium-iron-phosphate, or Thackeray’s own manganese spinel. Not only was it cheaper and safer, but Thackeray also calculated that the extra lithium in the system improved its performance. The double lattice let you pull out 60 or 70 percent of the lithium before collapsing, well over the 50 percent you could withdraw from Goodenough’s lithium-cobalt-oxide. That extra lithium—the added 10 or 20 percent—meant more energy.
    Thackeray called the invention “layered-layered,” or