Coated Positive Electrode for Secondary Battery Overcharge Safety

The coating layer is applied in advance to the current collector before the active material layer is formed. This preliminary action creates a protective interface that will automatically activate during overcharging conditions, disrupting conductive networks before thermal runaway can occur, thus improving safety without requiring additional active components during battery operation.

The coating layer acts as an intermediary between the current collector and the active material layer. It contains conductive agents and copolymers that mediate the electrical connection while providing safety functions. During normal operation, it maintains conductivity; during overcharging, it disrupts the conductive network to prevent safety incidents, thus resolving the contradiction between safety and complexity.

The coating layer's electrical resistance is designed to be dynamic rather than static. Under normal charging conditions, the conductive agents maintain low resistance for good electronic conduction. When overcharging occurs and temperature rises or voltage exceeds thresholds, the copolymer components undergo changes that increase resistance, disrupting the conductive network to prevent thermal runaway. This dynamic behavior allows the coating to adapt its conductivity based on operational conditions.

The coating layer utilizes changes in physical or chemical parameters (such as temperature, voltage, or molecular conformation) to switch between conductive and resistive states. The copolymer components are selected to undergo parameter changes under overcharging conditions, transforming the coating from a conductive state during normal operation to a resistive state during safety-critical conditions, thus resolving the contradiction between maintaining power and ensuring safety.