The rise of lithium-ion — and the silver technologies that survived

Introduction: a change of scale for silver

The years 1980–2010 are often described as an unequivocal victory for lithium. Broadly accurate, this overlooks two points. Lithium-ion won in stages: first in portable electronics, then in cars following a nickel–metal-hydride transition. Alternative chemistries also survived, concentrating on applications that valued their particular strengths rather than competing to become the universal mass-market battery.

For silver, this period split battery development into several specialised branches:

• silver–zinc batteries continued serving applications requiring high specific power, safety and compactness;
• Zinc Matrix Power, later ZPower, began systematically addressing the longstanding problems of rechargeable Ag–Zn chemistry;
• silver vanadium oxide cathodes became central to lithium batteries for implantable defibrillators;
• silver-ion solid electrolytes remained a subject of research for long-lived primary and laboratory solid-state cells;
• the main solid-state traction-battery research line gradually shifted towards lithium polymer, oxide and thin-film systems, in which silver was generally not a central material during this period.

1980–1991: the scientific foundations of lithium-ion

Rechargeable lithium cells existed in the 1970s, but lithium metal created serious safety challenges. Cycling could produce uneven deposits and structures capable of causing internal short circuits. A mass-market system needed to retain lithium's high voltage without relying on repeated reversible plating of a substantial metal anode.

A key step came in 1980, when John Goodenough demonstrated a lithium cobalt oxide cathode. It enabled roughly four volts, considerably above most common contemporary rechargeable batteries. In 1985, Akira Yoshino developed the first commercially viable lithium-ion design with a carbon anode that stored lithium reversibly without metallic lithium foil. Lithium-ion batteries entered the market in 1991.

The architecture combined several advantages:

• high operating voltage per cell;
• high specific energy;
• hundreds of cycles with appropriate management;
• relatively low self-discharge;
• a sealed rechargeable format suited to electronics;
• room to improve cathodes, anodes, electrolytes and controls without replacing the entire manufacturing platform.

That final advantage proved strategic. Lithium-ion became a family of compatible technologies rather than one fixed chemistry: LiCoO₂ and later NMC, LMO, LFP and other cathodes; graphite, titanate and emerging silicon-containing anodes; and cylindrical, prismatic and pouch formats.

The 1990s and 2000s: portable electronics first

Camcorders, laptops and mobile phones, rather than electric cars, first drove mass production. Low weight, long runtime and regular rechargeability mattered greatly in these devices. Their high value and clear user benefits could justify an initially more expensive battery technology.

Electronics created a reinforcing cycle. Volumes increased, electrode coatings, separators, electrolytes and quality control improved, and standard cell formats and protection electronics emerged. Lithium-ion acquired what many competitors lacked: a vast industrial base, sustained funding and manufacturing scale.

Silver–zinc could deliver high energy and power, and its aqueous electrolyte offered an important fire-safety advantage. But laptops and phones depended on a combination of cost, life, consistent production, charging electronics and a global supply chain rather than a single record cell metric. Lithium-ion was rapidly pulling ahead on that combination.

Cars: the nickel–metal-hydride bridge to lithium

Lithium's automotive success came later. In the 1990s, nickel–metal-hydride batteries looked promising for traction. Heavier than modern lithium-ion batteries, they nonetheless offered good cycle life, tolerance of demanding operating conditions and an established manufacturing base.

Several vehicles illustrate the transition:

• GM's EV1, one of the best-known production EVs of the 1990s, initially used lead–acid batteries and later nickel–metal-hydride packs;
• the Toyota RAV4 EV of the late 1990s used NiMH;
• the Toyota Prius, launched in Japan in 1997 as the first mass-produced hybrid, also relied on NiMH.

By the late 1990s, lithium dominated portable electronics but was not yet the obvious automotive winner. Automakers needed demonstrated durability, safety, temperature tolerance and the ability to manufacture large packs.

The change became clear in the 2000s. The Tesla Roadster, which entered regular production in 2008, demonstrated a traction pack built from thousands of relatively small cylindrical lithium-ion cells, supported by cooling and electronic controls. Nissan launched the LEAF with a 24 kWh lithium-ion battery in 2010, a major step from experimental and low-volume EVs towards a mass market.

Why silver–zinc did not become a mass-market chemistry

Silver–zinc offers attractive electrochemical properties, including high specific energy, high discharge current and an aqueous electrolyte with lower flammability than many organic lithium electrolytes. These benefits came with structural problems that became especially apparent during repeated cycling.

1. Zinc electrode shape change

In alkaline electrolyte, zinc reaction products can dissolve and redistribute. During recharge, material does not redeposit exactly where it started. The electrode loses its original geometry, active material migrates and some regions grow faster than others.

2. Dendrites and separator damage

Uneven zinc deposition can form structures that extend towards the positive electrode. Even a small separator defect can cause an internal short circuit. Ag–Zn life therefore depends on separator design, electrolyte and charging protocols as well as electrode chemistry.

3. Dissolution and migration of silver compounds

The silver positive electrode also changes during cycling. A durable system must control dissolution, transport and reformation of silver's active phases while preventing structural degradation and separator contamination.

4. Cost

Even with reduced silver content, the active material remains much more expensive than iron, manganese, nickel or carbon. Spacecraft, medical devices and military systems may accept that cost. For mass-market vehicle packs requiring tens of kilowatt-hours, it is a fundamental limitation.

By 1995, Ag–Zn had survived in applications where high power and safety mattered more than the lowest cost per kilowatt-hour.

Zinc Matrix Power and ZPower: addressing old Ag–Zn problems

Zinc Matrix Power, later renamed ZPower, was founded in 1996. Its aim was to redesign all the critical components of a silver–zinc battery: zinc electrode, silver cathode, electrolyte, separator and charging regime.

Patents from the early 2000s reveal this programme. Zinc Matrix Power developed matrices to retain zinc particles and restrict dissolved zincate transport. In the mid-to-late 2000s, ZPower patented oxidation-resistant separators, improved silver active materials and specialised pack-charging methods.

This matters in two ways. Ag–Zn research did not stop after 1980; it shifted from large aerospace and military batteries towards miniature rechargeable cells. ZPower also shifted attention from a single remarkable chemistry to an engineered system whose life depends on all components working together.

By the end of the period, the company was preparing silver–zinc batteries for consumer electronics and developing its charging platform. Calling the technology perfected by 2010 would go too far. It was more practical, but had not displaced lithium-ion at scale. ZPower's first commercial product, rechargeable hearing-aid button cells, arrived in 2013, beyond this article's timeframe.

Lithium and silver were not always rivals: Li/SVO

One of the period's most important silver-containing batteries was a primary lithium system with a silver vanadium oxide cathode, Li/SVO. Development for implantable cardioverter-defibrillators began in 1984.

Such devices need an unusual combination: years of low background current for electronics and brief high-power pulses for defibrillation. Silver vanadium oxide proved well suited to that load.

The first Li/SVO defibrillator cells appeared in the second half of the 1980s, and the chemistry became established in this medical-device class over subsequent decades. It is an important counterexample to the idea that lithium's rise necessarily excluded silver: the two materials could work together.

Solid-state batteries, 1980–2010: two parallel histories

Solid-state batteries did not suddenly appear in the 2020s. During 1980–2010, at least two research lines coexisted: lithium systems using polymer, glass and ceramic electrolytes, and silver-ion systems based on highly conductive solid compounds.

Lithium-polymer EV projects

A European project funded in 1990–1991 sought an all-solid-state rechargeable lithium-polymer EV battery. It targeted a roughly 1 kWh pack with a lithium anode, composite cathode and thin polymer electrolyte. Proposed performance reached 300 Wh/kg and 300–500 cycles.

Such programmes show that solid-state lithium traction batteries predate today's startup wave. Practical constraints, including room-temperature polymer conductivity, interlayer contact, lithium-metal stability and scale-up, prevented these systems from displacing liquid-electrolyte lithium-ion.

LiPON and Oak Ridge thin-film batteries

In the early 1990s, Oak Ridge National Laboratory researchers developed lithium phosphorus oxynitride, LiPON. Deposited as a thin dense layer, it conducted lithium ions, provided strong electronic insulation and showed good stability against lithium metal.

LiPON enabled working thin-film solid-state microbatteries. In 2000, an ORNL team described a cell assembled without lithium metal, which formed on a copper current collector during the first charge. Tests exceeded 1,000 cycles at moderate current density. By 2010, researchers were studying LiPON deposition on three-dimensional microstructures to increase active area.

This was a major solid-state branch, but silver was not central to its conventional architecture. The main materials were lithium, LiCoO₂, a copper current collector and LiPON.

Silver-ion solid electrolytes

Another line involved solid-state batteries whose mobile ion was Ag⁺. A prominent electrolyte was RbAg₄I₅, rubidium silver iodide, with exceptionally high room-temperature ionic conductivity.

Results for Ag/RbAg₄I₅/I₂ batteries after ten years of storage were published in 1983. After twenty years, testing in 1993 found approximately 90% of initial capacity, corresponding to average self-discharge of about 0.5% annually. In 2007, samples stored for 33 years could still deliver roughly 75% of their original capacity.

During the 1990s, researchers also built primary solid-state cells with silver-containing glassy fast-ion conductors, including AgI–Ag₂O systems with vanadate, arsenate, selenite and phosphate glass formers. Silver remained an active research subject as both charge carrier and solid-electrolyte constituent.

How the main approaches developed

Conclusions

Between 1980 and 2010, a new battery-industry structure emerged.

Lithium-ion gained a decisive advantage through high voltage, specific energy and improvement within one manufacturing platform. Portable electronics financed scale-up, and accumulated experience enabled automotive adoption in the late 2000s. NiMH provided a bridge, demonstrating viable electric and hybrid drivetrains before lithium-ion was ready for mass traction use.

Silver–zinc could not compete on cost and cycle life in large mass-market batteries but retained distinctive advantages. ZPower's research showed how coordinated engineering of electrodes, separators, electrolyte and charging could address longstanding problems. It later produced commercial microbatteries, while its intellectual property and technology base passed to Riot Energy.

Silver also found a successful role within lithium chemistry through medical silver vanadium oxide cathodes, while silver-ion solid-state cells continued as a separate branch with exceptional shelf life.

Lithium became the broad mass-market platform; silver became an expensive functional material for applications where its properties justified the price. The same logic reappeared in the 2020s as silver returned to research on lithium-metal and solid-state interfaces.

Key sources

1. Nobel Prize — Goodenough, Yoshino and the commercialisation of lithium-ion.
2. US Department of Energy — EV history, EV1, Prius and NiMH.
3. Toyota — Prius development and its NiMH battery.
4. Tesla — start of regular Roadster production in 2008.
5. Tesla Service — the Roadster lithium-ion battery.
6. Nissan — lithium-ion technology and the 2010 LEAF launch.
7. Riot Energy — Zinc Matrix Power, ZPower and the 2021 asset acquisition.
8. Riot Energy — the history of rechargeable silver–zinc batteries.
9. Zinc Matrix Power patent for a zinc-anode matrix.
10. ZPower patent for an oxidation-resistant Ag–Zn separator.
11. ZPower patent for silver–zinc battery charging.
12. Takeuchi et al., 1988 — Li/SVO batteries for implantable defibrillators.
13. CORDIS — European solid-state lithium-polymer battery project, 1990–1991.
14. Oak Ridge National Laboratory — LiPON's development in the early 1990s.
15. ORNL/OSTI — a thin-film lithium-free battery using lithium plating, 2000.
16. ORNL — LiPON for three-dimensional solid-state batteries, 2010.
17. Owens & Bottelberghe, 1993 — Ag/RbAg₄I₅/I₂ batteries after 20 years of storage.
18. Owens, Reale & Scrosati, 2007 — a silver solid-state battery after 33 years of storage.
19. Karthikeyan & Satyanarayana, 1994 — silver-containing glassy solid electrolytes.