There is a tax every lithium-ion cell pays on its first charge, and most owners never know it. The very first time the cell charges, some lithium is consumed to build the solid-electrolyte interphase — a thin protective layer on the anode that is essential for the cell to work, but which permanently locks away lithium that will never store energy again. That is the first-cycle capacity loss.For a graphite anode the loss is modest, a few percent. For a silicon-rich anode it can be severe, because silicon's huge surface area and swelling consume far more lithium building and rebuilding that interphase. As the industry pushes silicon into anodes for higher energy density, the first-cycle tax grows from a nuisance into a real penalty.Bosch's US11769900B2, granted in September 2023, claims a lithium-ion battery and a prelithiation method for the anode. Prelithiation is exactly what it sounds like: add extra lithium to the cell up front, so that when the first-cycle loss claims its share, there is a reserve to cover it and the usable capacity stays high. You pre-pay the tax with sacrificial lithium.The mechanism has a few flavors — depositing lithium directly on the anode, adding a lithium-rich additive, or using a sacrificial material that releases lithium on the first charge. The engineering challenge is doing it controllably and safely in a factory; adding reactive lithium metal to an electrode is not a casual manufacturing step.Does it pencil? Prelithiation adds cost and process complexity, so it has to buy back more value than it spends. For a silicon-heavy, high-energy cell where the first-cycle loss would otherwise be large, recovering that capacity can be decisive — it can be the difference between a silicon anode that beats graphite on usable energy and one that merely matches it. For a plain graphite cell, the modest loss often is not worth the trouble.The practical signal for readers: when a cell maker talks up a high-silicon anode, ask how they handle first-cycle loss. Prelithiation is one of the few honest answers, and its presence in the IP is a sign the maker has thought past the headline capacity number to the usable one — which is the only number that matters in the field.