The 1980s marked a pivotal era in battery development as researchers pursued high-energy-density rechargeable lithium-metal batteries. Moli Energy, a Canadian company, commercialized the first rechargeable lithium-metal batteries using a molybdenum disulfide cathode and a lithium-metal anode. These batteries promised significantly higher energy density compared to the nickel-cadmium and lead-acid batteries of the time, making them attractive for emerging portable electronics. However, catastrophic safety failures ultimately led to the technology's abandonment, reshaping the trajectory of lithium battery development.

Moli Energy's batteries operated on the principle of lithium-metal plating and stripping during charge and discharge cycles. The lithium-metal anode offered a theoretical capacity of 3,860 mAh/g, far exceeding conventional anode materials. Early prototypes demonstrated energy densities above 150 Wh/kg, nearly double that of nickel-cadmium systems. Commercial cells entered the market in the mid-1980s, targeting applications such as camcorders and early laptops. However, within months of deployment, reports emerged of cells catching fire during charging or even during storage. The most severe incidents involved explosive failures that propelled battery components with enough force to damage surrounding equipment.

The root cause of these failures lay in the fundamental instability of lithium-metal anodes during cycling. During charging, lithium ions reduced and deposited onto the anode surface. Instead of forming a smooth, uniform layer, the lithium tended to grow as dendritic filaments. These dendrites were needle-like structures that extended through the electrolyte toward the cathode. Dendrite formation accelerated with higher charging currents, deeper discharge cycles, and repeated cycling. Microscopic analysis of failed cells revealed dendrites penetrating separators as thin as 25 microns, creating internal short circuits.

Electrolyte chemistry exacerbated the dendrite problem. The liquid electrolytes of the 1980s consisted of lithium salts like LiClO4 or LiAsF6 dissolved in organic solvents such as propylene carbonate or dimethoxyethane. These systems lacked the stability to form an effective solid-electrolyte interphase (SEI) on the lithium-metal surface. The SEI that did form was heterogeneous and brittle, cracking under the mechanical stress of lithium deposition. Fresh lithium exposed by these cracks reacted violently with the electrolyte, generating heat and gaseous byproducts. Post-mortem analysis of failed cells detected hydrogen, methane, and ethylene gas—all products of electrolyte decomposition.

Thermal runaway presented the most severe risk. When dendrites caused an internal short circuit, the localized heating could exceed 180°C, initiating exothermic reactions between the lithium metal and electrolyte. The heat accelerated further decomposition reactions, creating a positive feedback loop. Infrared imaging recorded temperature spikes exceeding 600°C in under 60 seconds during failure events. Unlike modern lithium-ion batteries, the 1980s lithium-metal systems contained no flame retardants or shutdown separators to mitigate these reactions.

Moli Energy implemented multiple design changes to address these issues. Engineers thickened the separator to 50 microns, added electrolyte stabilizers, and incorporated pressure-release vents. Cycling protocols limited depth-of-discharge to 80% and mandated slow charging below 0.5C rates. These measures reduced failure rates but compromised the battery's performance advantages. Energy density dropped below 120 Wh/kg, while the charging restrictions made the batteries impractical for many applications. Despite these compromises, safety incidents persisted.

The technology's downfall came in 1989 when a series of fires in Japan prompted a massive recall of Moli Energy's batteries. Investigators determined that manufacturing inconsistencies led to microscopic metal particles contaminating the electrode layers. These particles acted as nucleation sites for dendrite growth, causing premature short circuits. The recall bankrupted Moli Energy, and the company's assets were acquired by a consortium that shifted focus to lithium-ion development.

The failure of rechargeable lithium-metal batteries had lasting consequences for battery research. It demonstrated that energy density alone couldn't guarantee commercial viability when paired with safety risks. The industry pivoted to intercalation-based lithium-ion systems, which sacrificed some energy density for stability. Modern research on lithium-metal batteries incorporates lessons from the 1980s failures, employing advanced electrolytes, artificial SEI layers, and mechanical barriers to suppress dendrites. While lithium-metal technology may yet achieve commercial success in solid-state configurations, its initial failure serves as a cautionary tale about the challenges of balancing performance and safety in electrochemical systems.

Analysis of the failed cells provided critical insights into battery failure modes. Researchers identified three distinct phases of thermal runaway in lithium-metal cells: initiation by dendrite penetration, acceleration through electrolyte decomposition, and catastrophic failure via electrode combustion. These findings informed safety standards for subsequent battery technologies, including mandatory abuse testing protocols. The 1980s experience also highlighted the importance of manufacturing control, as minor impurities could dramatically impact safety.

The abandonment of rechargeable lithium-metal batteries delayed high-energy-density systems by nearly two decades but ultimately guided the development of safer alternatives. Contemporary battery engineers still grapple with dendrite formation in next-generation systems, applying the hard-won lessons from this early commercial failure. The Moli Energy case remains a benchmark for assessing new battery technologies, emphasizing that commercial viability requires not just high performance but inherent safety across all operating conditions.