It is with sadness that Batteries International reports the death of Paul Rüetschi, on April 19, a year short of his 100th birthday. The Swiss-born scientist became a legend in his lifetime as one of the deep explorers and explainers of lead batteries.

Rüetschi — pronounced Richey — was born in 1925 in Schafisheim, a small town in the Swiss district of Lenzburg and a half hour’s drive from Zurich. An early aptitude for science led to studies at the Teacher’s College in Wettingen and then on to the Federal Institute of Technology in Zurich. 

The institute — known in German as ETH Zurich — was already one of the most famous polytechnics in Europe. Today it is ranked third in the continent, just behind Oxford and Cambridge. In the 1950s it was quite simply one of the foremost institutions of its kind in post-war Europe. 

It was at ETH that Rüetschi’s first full involvement with the world of batteries and energy storage began. And it was here he obtained a PhD from the Department of physical chemistry, studying under its professor, Gottlieb Trumpler, a leader in his field at this time. 

His research work made a major contribution to the understanding of electrochemical passivation of metals of decisive importance in the field of corrosion. His work included polarography, the electrolytic deposition of metals, the flow of material on electrolysis, and the examination of chemical and physical equilibriums. 

There was a strong bond in the relationship between Rüetschi and Trumpler. In Rüetschi, Trumpler found a collaborator, eager and quick to learn. For Rüetschi, Trumpler was a keen and sympathetic teacher and provided the gateway to much of his later research.

In 1953, Rüetschi received the first of his industry awards: the silver medal of the ETH. Rüetschi stayed with Trumpler as his assistant until 1955, only leaving for a year’s sabbatical in a research group in the US run at Louisiana State University, Baton Rouge, by Belgium electrochemist professor Paul Delahay. 

ESBC (Exide Technologies)

The results of their collaboration resulted in a joint publication in the US, Influence of Electrode Material on Oxygen Overvoltage: A Theoretical Analysis. America impressed Rüetschi but so did the practical application of his research work. And, aged 30, he returned to the US, this time to take the position of manager of the electrochemical research department at the Electric Storage Battery Company — nowadays better known as Exide Technologies.

Here he was involved in a number of investigations relating to lead acid batteries, though other disciplines were connected. One of his first studies, for example, was the development of fuel cell type auxiliary electrodes for gas consumption in sealed lead acid cells. 

Another area of research was the study of corrosion phenomena and the composition of multilayer corrosion films on lead and lead alloys. His second official honour came in 1957, when he was presented with the Young Author Award by the Electrochemical Society. As an example of his multi-disciplinary approach to energy storage, in 1961 he filed a patent for an “improved storage battery utilizing positive electrodes of zinc or magnesium … another object of the present invention is to provide a new and improved electrolyte for use in batteries of the so-called alkaline type”. 

He was also active in many scientific societies. During his time in the US, Rüetschi became chairman of the physical electrochemistry division of the electrochemical research department for the Electrochemical Society, as well as executive committee officer of the battery division. Perhaps the haunting ring of the bells echoing around the Jura mountains was too great and nine years after arriving in the US, in 1964, Rüetschi returned to Switzerland.

The Leclanché years

His new position at Yverdon-les-Bains was technical director at Leclanché, a manufacturer of a wide range of primary and secondary batteries. The firm itself dates back to the development of zinc carbon batteries by Georges Leclanché in 1866, and the creation of the company in 1909. He was to remain at Leclanché for the next 28 years. 

With characteristic energy, Rüetschi threw himself into work at Leclanché and under his guidance, research took off. This included a quantitative description of the pH gradient that exists in corrosion layers and alkaline primary battery electrolyte-lithium miniature primary batteries with long service life. 

Rüetschi continued to make major contributions in lead acid battery research, including: 

• the discovery of αPbO2 in corrosion films formed on lead and lead alloys at high anodic potentials 
• disclosure of the individual self-discharge processes in lead acid batteries, and the stability of lead oxides in H2SO4 solution 
• determination of the composition of the corrosion layer on lead electrodes in H2SO4 at various potentials; investigation of ion selectivity and diffusion potentials in such corrosion layers; quantitative description of the pH gradient in the corrosion layer 
• development of a cation-vacancy model that relates defects in the crystallographic structure of MnO2 and PbO2 to their electrochemical activity 
• various other achievements in the research of HgO, Zn, MnO2 and Ag2O electrodes. 

By this time he had already attracted an international audience for his research. One leading industry figure later said: “In the 1950s, many authors writing about their battery findings were vague and imprecise in describing what they did and what they found out. 

“They were only soft and qualitative in their conclusions. Often they did not clarify what was hard proven fact and what was merely speculation. 

“By contrast Rüetschi’s papers have always presented results in a quantitative manner, providing values and potential variations in detail, and considering potential disturbances. Sample preparation and conditions of the experiments were precisely described. Conclusions were clear in wording, without any kind of speculative touch.” 

The breadth of his research was deepened by his now extensive contacts with the electrochemical giants of the day across Europe. “Contacts provide new ideas. Without contacts, the performance suffers; there is premature capacity loss!” he later said. 

He also later paid tribute to the memory of Detchko Pavlov, professor at the Bulgarian Academy of Sciences, and Pavlov’s co-workers describing how his own work had been stimulated by Pavlov’s series of conferences held in Varna, Bulgaria from 1989 onwards. 

In 1978, Rüetschi published the seminal paper Review on the lead-acid battery science and technology in the Journal of Power Sources. It begins: “In spite of extensive and continued efforts aimed at developing new light-weight, low-cost secondary electrochemical power sources, the old lead-acid battery has still not been dethroned as the major battery system.” 

It concludes: “What makes it so hard for new electrochemical power sources to compete with it is not only its long head-start, but also the high degree of sophistication and perfection it has reached.” 

He was both right and wrong, as history would later prove. 

In 1980 he was awarded the Frank Booth Medal of the International Power Sources Conference Committee. In 1988 Eberhard Meissner — who later became senior technical leader, electrochemistry at Clarios (the former Johnson Controls Power Solutions) but then giving his first public presentation at the International Power Sources Symposium in Bournemouth, UK — met Rüetschi. 

“He was very interested in the relaxation effects of PbO2, which I presented, and my interpretation,” he recalls. “In his polite and precise manner, he asked several questions in the Q&A — it was a great feeling for a youngster like me. He was one of those scientists whose publications I admired from the very beginning. Rüetschi combined the values of a scientific education with expertise in the battery industry.”

Rüetschi retired, aged 67, at the end of 1992, although he continued to work part-time as a consultant for Leclanché. 

The following summer he was awarded the Gaston Planté medal — the electrochemical battery equivalent of an Oscar — for his “significant contribution to the development of lead-acid battery science and technology”. 

But his life in research and problem solving was not over. Four years after retiring, and then into his seventies, Rüetschi, the doyen of lead acid batteries, was still writing and still excited at the wave of new technologies and chemistries emerging. 

Alongside Felix Meli and the late Johann Desilvestro, he co-authored the paper Nickel-Metal Hydride Batteries. The Preferred Batteries of the Future? 

His last battery book, Batterien und Akkumulatoren: Mobile Energiequellen für Heute und Morgen, was written with Lucien Trueb, science editor of a Swiss daily newspaper. Batteries and Accumulators, Mobile Energy Sources for Today and Tomorrow was written to be understandable and easily readable — for laymen as well as scientists. 

As late as 2002, Rüetschi received a patent for a lead battery into which at least one silver-silver sulfate reference electrode was permanently integrated. The reference electrode is used to control the charging or discharging of the battery, and can also be used to measure the acid density and charging state of the battery. 

In total Rüetschi has contributed to more than 70 scientific publications and been granted more than 30 patents.

Like another of the battery giants of the last century — John Goodenough, one of the creative greats of the lithium battery  — both were men of faith in the Christian tradition. Both firmly believed in the benevolence of a caring God who was keen to let mankind unpick and examine the wonders of his creation.