Section 1 · Topic 1
History and Evolution of Li-ion Cells
The rechargeable lithium cell began as a materials problem that took two decades to solve: lithium metal is the ideal anode on paper and unusable in practice.
Metallic lithium holds the most negative electrode potential of any candidate, −3.04 V versus the standard hydrogen electrode (SHE), and the lowest density, 0.534 g cm⁻³ — together promising the highest cell voltage and gravimetric capacity available to any chemistry. During charge, however, lithium does not re-deposit as a smooth film; it nucleates as needle-like dendrites that grow through the separator, bridge the electrodes, and drive an internal short. This dendrite failure mode stalled the first generation of rechargeable lithium cells and pushed the field toward host materials that store lithium by insertion rather than plating.
From metallic lithium to intercalation
Whittingham built the first working rechargeable lithium cell at Exxon in 1976, pairing a lithium-metal anode with a titanium disulfide (TiS₂) cathode that intercalated Li+ between its sulfide layers. The cathode worked; the anode did not, and dendrites persisted. Goodenough removed the next bottleneck at Oxford in 1980 by identifying lithium cobalt oxide (LiCoO₂), a layered oxide that releases and reaccepts lithium reversibly near 4 V — high enough that the cathode itself could serve as the cell’s lithium reservoir, removing the need for a metallic-lithium anode.
The carbon anode and the first practical cell
Yazami demonstrated in the early 1980s that graphite reversibly intercalates lithium, but early graphite anodes degraded in the propylene-carbonate electrolytes of the era — an incompatibility resolved in Topic 3. Yoshino assembled the first practical lithium-ion cell at Asahi Kasei in 1985 using petroleum coke, a disordered soft carbon, sidestepping that incompatibility and eliminating metallic lithium from the cell. Sony commercialised the architecture in 1991 against a LiCoO₂ cathode.
The first commercial Sony cell did not use a graphite anode — it used a hard-carbon / petroleum-coke host. Graphite anodes became practical only later in the 1990s, once ethylene-carbonate-based electrolytes displaced propylene carbonate (Topic 3). The often-repeated “graphite anode in 1991” compresses a decade of electrolyte development into a single step.
Diversification and recognition
The 2000s brought rapid cathode diversification to improve safety and cost, producing lithium iron phosphate (LFP) and nickel-manganese-cobalt (NMC) architectures, while the rise of electric vehicles scaled manufacturing by orders of magnitude. In 2019 the Nobel Prize in Chemistry recognised Whittingham, Goodenough, and Yoshino for the sequence of breakthroughs that produced the technology.
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