LiCoO2 Cathode Electrolyte Design for High-Voltage Cycle Stability

The patent applies composite materials by combining LiCoO2 with doping elements (such as Al, Mg, Ti, Zr, Nb, Ta, or W) to create a doped lithium cobalt oxide composite. This composite structure maintains the spinel framework while incorporating foreign atoms that stabilize the lattice, enabling operation at high voltages above 4.2 V without suffering from the lattice deformation and structural instability that would normally occur. The composite approach allows simultaneous achievement of high capacity and structural reliability.

The patent introduces an electrolyte containing specific additives (such as sultone compounds, cyclic carboxylate compounds, or their combinations) that act as intermediaries between the LiCoO2 positive electrode and the electrolyte. These additive molecules preferentially react or adsorb onto the electrode surface to form protective films that prevent direct contact between the electrolyte and the electrode material during deep delithiation. This intermediary layer suppresses harmful side reactions, reducing gas production and corrosion while allowing full utilization of lithium ions at high voltages.

The patent applies preliminary action by pre-forming stable surface films on the LiCoO2 electrode through the use of doping elements and electrolyte additives before the battery undergoes normal cycling. The doping elements are incorporated into the lattice structure in advance to prevent degradation, while the electrolyte additives form protective films during initial cycles. This preliminary stabilization prevents subsequent capacity loss during high-voltage operation, allowing the battery to maintain both long cycle life and high capacity retention simultaneously.