The development of modern rechargeable batteries has been a story of intense competition between alternative chemistries, with lithium-ion ultimately emerging as the dominant technology. However, this outcome was far from certain during the 1980s and 1990s, when multiple systems vied for supremacy. Several alternative battery chemistries reached advanced stages of development and commercialization before being displaced by lithium-ion, with technical limitations, manufacturing challenges, and economic factors determining their fates.

Nickel-metal hydride batteries represented one of the most successful alternatives to lithium-ion during this period. Building upon earlier nickel-cadmium technology, NiMH systems offered improved energy density and eliminated the toxic cadmium that made NiCd environmentally problematic. By the early 1990s, NiMH had achieved energy densities around 70-80 Wh/kg, significantly better than NiCd's 40-60 Wh/kg. This made them attractive for consumer electronics and early hybrid electric vehicles, with the Toyota Prius initially adopting NiMH technology. However, NiMH faced fundamental limitations that would eventually relegate it to niche applications. The chemistry suffered from higher self-discharge rates than lithium-ion, typically losing 1-2% of charge per day compared to lithium-ion's 0.5-1%. Voltage output was also lower at 1.2V per cell versus lithium-ion's 3.6V, requiring more cells in series for equivalent applications. Most critically, NiMH energy density plateaued around 100 Wh/kg while lithium-ion systems rapidly surpassed 150 Wh/kg by the late 1990s.

Lithium-polymer batteries emerged as another serious contender during lithium-ion's ascendancy. These systems used polymer electrolytes instead of liquid ones, theoretically enabling thinner, more flexible battery designs. Several major electronics manufacturers invested heavily in lithium-polymer development during the 1990s, attracted by the potential for ultra-thin form factors in mobile devices. Early lithium-polymer cells achieved thicknesses below 1mm, compared to several millimeters for conventional lithium-ion. However, the technology struggled with two key issues: lower ionic conductivity in polymer electrolytes reduced power output, and manufacturing complexities increased costs. While some hybrid designs incorporating gel polymers found limited success, true solid polymer systems failed to match the performance or cost-effectiveness of liquid electrolyte lithium-ion. By the early 2000s, most development efforts had shifted toward improving conventional lithium-ion rather than pursuing pure polymer approaches.

Rechargeable lithium-metal batteries represented perhaps the most technically promising alternative that ultimately failed to commercialize. These systems used metallic lithium anodes rather than the intercalation compounds used in lithium-ion, offering potentially much higher energy density. Several companies, including Moli Energy, brought lithium-metal rechargeable batteries to market in the late 1980s. These cells achieved energy densities exceeding 150 Wh/kg, surpassing contemporary alternatives. However, catastrophic safety failures stemming from lithium dendrite formation led to large-scale recalls and bankruptcies. Dendrites could penetrate separators and cause internal short circuits, sometimes resulting in violent thermal runaway. Despite extensive research into dendrite suppression techniques, including advanced separators and electrolyte additives, no commercially viable solution emerged that could guarantee safety over hundreds of cycles. The lithium-metal approach was largely abandoned for rechargeable applications by the mid-1990s, though it remains an area of research today in next-generation solid-state batteries.

Sodium-sulfur batteries developed along a completely different technical path and found some success in stationary applications. Operating at high temperatures around 300°C, these liquid-metal batteries offered excellent energy efficiency and cycle life. Several megawatt-scale installations were deployed for grid storage beginning in the 1980s, particularly in Japan. The chemistry provided distinct advantages for large-scale applications, including high energy density for its class and the ability to deliver high power when needed. However, the need for precise temperature maintenance and safety concerns stemming from highly reactive sodium and sulfur prevented broader adoption. Maintenance costs proved prohibitive for most applications, and the technology remained confined to specialized grid storage uses where its particular advantages outweighed these drawbacks.

Nickel-zinc batteries underwent periodic revivals as potential alternatives, particularly for applications requiring high power density. The chemistry offered several appealing characteristics: a relatively high 1.6V cell voltage, good power capability, and environmentally benign materials. Several companies commercialized NiZn batteries in the 1990s for power tools and other high-drain devices. However, cycle life limitations stemming from zinc electrode shape change and dendrite formation typically restricted these systems to a few hundred cycles at most. While incremental improvements continued, NiZn could never match lithium-ion's combination of energy density and cycle life, relegating it to specialized roles where its power characteristics were particularly valuable.

The economic factors influencing these technological outcomes were as important as the technical considerations. Lithium-ion benefited from a virtuous cycle of investment and improvement that alternative systems could not match. As consumer electronics companies standardized on lithium-ion for laptops and mobile phones in the 1990s, manufacturing scale increased dramatically, driving down costs through economies of scale. Between 1991 and 2001, lithium-ion production costs decreased by approximately 70% while performance improved significantly. Alternative chemistries lacked comparable market drivers to achieve similar scaling benefits. Additionally, the modular nature of lithium-ion cells allowed flexible adaptation to different form factors and applications, giving them an advantage over systems like sodium-sulfur that required completely different designs for different uses.

Materials availability also played a crucial role in determining which technologies succeeded. Lithium-ion's reliance on relatively abundant materials like graphite and transition metal oxides proved more sustainable than systems depending on scarcer elements. While cobalt supply would later become a concern, in the 1990s the materials situation favored lithium-ion over alternatives like nickel-metal hydride that required significant amounts of rare earth elements. The development of cobalt-free lithium-ion variants further strengthened its position against materials-constrained alternatives.

The standardization of lithium-ion interfaces and charging protocols created network effects that alternative chemistries could not overcome. As electronic devices increasingly designed their power systems around lithium-ion's voltage characteristics and charging requirements, the switching costs to alternative chemistries became prohibitive. This standardization extended to manufacturing equipment and testing protocols, creating an entire ecosystem optimized for lithium-ion that would require massive investment to replicate for competing systems.

Safety certification processes also favored lithium-ion's evolutionary improvement over more radical alternatives. Regulatory frameworks developed around lithium-ion technology, making it easier to incrementally improve existing designs than to certify completely different chemistries. The well-understood failure modes of lithium-ion, coupled with established protection circuitry approaches, gave it an advantage in safety-critical applications despite alternatives potentially offering better theoretical performance.

In retrospect, lithium-ion's dominance resulted from a combination of technical superiority in key metrics and self-reinforcing economic advantages that emerged during a critical period of battery market expansion. While alternative chemistries each had particular strengths, none could match lithium-ion's balance of energy density, power capability, cycle life, and cost across the broad range of applications that emerged during the digital revolution. The technologies that came closest to challenging lithium-ion's position ultimately failed due to specific technical limitations that prevented them from scaling effectively or meeting evolving market demands. This historical development path continues to influence battery research today, as new chemistries must demonstrate not just technical superiority but also compatibility with existing manufacturing infrastructure and application requirements to have any chance of displacing lithium-ion's entrenched position.