Thirty years at DFG is a long time, but I can say that my father always found his work exciting because he could experience research up close at his position. He has always endeavored to stay as close as possible to the areas of expertise he supervised. My father used the following words to describe what was really appealing about being a DFG subject officer: “You deal with many scientists who are enthusiastic about their work, and I got infected by that enthusiasm”.
When he joined Li-Tec Battery GmbH, the development of cell and battery technology for use in electric vehicles became a major topic of Walter Lachenmeier’s creative work in the engineering field (Table 2).
Major Objectives |
Summary of the Claims |
Title of Patent |
Patent No. a |
Improve and enhance the performance and lifetime of batteries |
Profile strip as protective sheath in battery cells |
Profile strip for an electrochemical energy storage device |
US 2012/0231310 A1 [15] |
Cooling or magnetic liquid as a means to transport the generated heat |
Cooling device and method for cooling an electrochemical energy store |
DE 10 2011 100 602 A1 [16] |
Heat-exchanging tubes with cooling liquids or gases along the surface of the battery |
Battery cooling system |
US 2012/0164507 A1 [17] |
Cooling the system by heat extraction and re-evaporation using refrigerant and absorber |
Temperature-controlled battery system |
US 2012/0189893 A1 [18] |
Peltier module to generate a temperature difference due to a change in circuit current |
Temperature-controlled battery system II |
US 2012/0129020 A1 [19] |
Placing a Galvanic cell, cell jacket, heat conducting unit, cell holder, temperature detector and a control unit with the cell. |
Accumulator with extended durability |
US 2012/0164492 A1 [20] |
Glass fiber nets as a temperature sensor are arranged in parallel across the surface of the separator in cell |
Electrical unit working in accordance with Galvanic principles |
US 8434940 B2 [21] |
Adding of sensors and control units during the production process to control the performance of the electrochemical cells |
Method for increasing the charging capacity of an electrochemical cell comprising a sensor, electrochemical cell comprising a sensor and a production method therefor |
WO 2012/156091 A1 [22] |
Arrangement, connection and configuration of cells and batteries |
Interconnecting the terminals of the adjacent batteries to create stack |
Battery arrangement and method for the production thereof |
US 2013/0052506 A1 [23] |
Battery receiving device, which is lockable and clamped to maintain the position of the battery |
Battery receiving device |
US 2012/0164496 A1 [24] |
Battery modules are arranged in a cuboid shape, which saves space and is easy to arrange |
Battery module |
US 2012/0171552 A1 [25] |
Placing the current conductor in mirror symmetry to create a stack |
Electric power cell and electric energy unit |
US 2012/0301775 A1 [26] |
Arresters and spacers to improve the battery output |
Stacked electric power unit |
DE 10 2010 006 390 A1 [27] |
A fixed battery connector reduces chemical loss during the battery working |
Contacting element |
US 2012/0156544 A1 [28] |
Sealed designed battery to avoid leakage, electrical charge drainage and lower battery efficiency |
Method for producing an electrochemical energy storage device and electrochemical energy storage device |
DE 10 2010 023 940 A8 [29] |
Efficiency increases in the supply and storage of energy |
Strategy to store energy by converting kinetic energy into mechanical energy |
Assembly and method for supplying energy to motorized vehicles |
US 2012/0153874 A1 [30] |
Enhancement by using a control unit, mechanical power and a shock absorber |
Method and charging apparatus for charging a motor vehicle battery |
US 2012/0133334 A1 [31] |
Non-pressurized and pressurized heat exchanger using ball circulation |
Ball circulating heat accumulator for storing heat from renewable energy sources has balls that are used in heat exchanger, such that geometrically defined guidance of balls to closed pipes or open channels system is performed |
DE 10 2012 019 791 A1 [32] |
Production of particles using nozzle type reactor |
High-pressure gas stream to produce particles from precursors |
Method and device for producing particles |
DE 10 2006 055 703 A1 [9] |
a Most patents were registered in various jurisdictions worldwide. For clarity reasons, the US patent is preferred for citation. If not available, German (DE) patent citations are used.
Generally, Walter Lachenmeier hoped to increase the charging capacity of lithium-ion batteries. By the development of new cathode materials, he expected to have a charging capacity that would well exceed 1 kWh/kg. If it is possible to achieve up to 2 kWh/kg, the range of passenger cars powered only by an electric motor would be equivalent to that of gasoline-powered cars.
The electrochemical cell construction and operation conditions were improved to enhance the performance and lifetime of the battery:
Profile strips may be used to increase the performance and lifetime of the electrochemical cell used in lithium-ion batteries and other conventional batteries. By providing a shielding to the electrochemical cell using a profile strip as a protective layer, the safety of the cell and its performance can be improved
[15].
Cooling and heating of the battery to maintain its temperature improves its lifetime and efficiency. A cooling or magnetic liquid may be used as a means to transport the heat generated by the electrochemical cell to the cooling liquid. Examples of magnetic fluids include ferro-fluids containing MnZnFe
2O
4 and gadolinium, which work on the principle of the magnetocaloric effect
[16]. Similarly, heat-exchanging tubes consisting of cooling liquid or gases may be placed alongside the surface of the battery. The cooling liquid moves into the heat exchange tubes near the bore of the battery cell. In an electric car, the cooling liquid can be obtained from the engine cooler of the car, making it a continuous system of controlling the temperature of the battery
[17]. Alternatively, an absorption cooling device may be used as a means to cool the system by heat extraction and re-evaporation. This system uses refrigerants such as water or ionic fluids as absorbers, which absorb heat, cool the electrochemical cell and evaporate
[18]. However, due to the increase in space for the placement of the cooling chamber, another alternative is to add a Peltier module. The Peltier module is used to generate a change in the temperature difference due to changes in the circuit current, alongside the battery to help reduce the temperature of the battery, which is created due to the high temperatures caused by charging and discharging
[19].
Extending the durability of the battery was possible by making a compact system consisting of a Galvanic cell placed inside a cell jacket, a heat conducting unit, a cell holder, a temperature detector and a control unit. The control unit supervises the function of the Galvanic cell, while the cell holder and cell jacket protect the acid present in the battery from spilling. The heat conducting unit is suited to supply heat output to the Galvanic cell and/or dissipate it from the Galvanic cell, making the system a durable battery
[20].
The temperature change in the electrochemical cell may be analyzed using a temperature sensor. A lithium-ion battery working on the Galvanic principle is used alongside a glass fiber, which acts as temperature sensor. The net of glass fibers is arranged in parallel across the surface of the separator or the cathode to analyze the temperature of the device, helping to avoid hazardous battery overheating
[21]. The charging capacity of an electrochemical battery cell used in electric vehicles can be enhanced by adding sensors. Sensors, mainly magnetoresistive sensors, are placed between the active electrodes. The invention includes taking data of the parameters from the sensors placed in individual electrochemical cells and sending those data to a control unit. The control unit compares the measured values with the target values, analyzing the overall performance of the electrochemical cell
[22].
To attain the proper working of the electric car, the arrangement of the cells into the batteries as well as the battery configuration are important parameters to be considered. Walter Lachenmeier has suggested the following advancements:
The battery arrangement can be carried out by connecting one or multiple batteries using interconnectors from the terminal of the batteries using a metal forming process for bending the battery terminal. The arrangement of batteries to increase the output of the electrochemical cell includes interconnection of the terminals of the adjacent batteries. The first and last terminals of the interconnected batteries are then connected to the outlets of the battery casing, making it a large battery system to operate the electric car
[23].
A battery-receiving device was invented. The size of the device chamber depends on the dimension and number of batteries that are lockable and clamped to maintain the position of the battery. The multiple battery chambers containing the batteries are arranged so that thermal energy can be exchanged between the batteries, which are connected to the coolant system to maintain their operating temperature, ensuring battery performance and battery life
[24]. This invention also offers the possibility of implementing battery exchange systems, which were thought by Walter Lachenmeier as being one of the most sensible solutions to increase the range of electric vehicles, which was rather restricted at that time
[33][34]. Walter Lachenmeier summarized the following arguments for battery exchange systems
[35]: (i) changing systems would make electric cars suitable for long journeys because the changing process at automatic stations only takes a maximum of 5 min. A long motorway journey could be interrupted several times for 5 min, but not for an hour at a time to charge the battery; (ii) rapid charging damages the battery and leads to considerable losses due to heat generation; (iii) in the magazine of the exchange stations, the batteries can be charged optimized for maximum service life. Aged batteries can also be offered because the customer only pays for the kilowatt-hour charge purchased; and (iv) the batteries stored in the magazine could really make a significant contribution to grid stabilization. Almost 10 years later, the first suppliers are currently offering battery swap stations.
Adjacent batteries may be connected to create a battery module. The batteries are arranged in the module in a cuboid shape. The advantages of the cuboid over conventional shapes include its easy planar arrangement, which saves space, its easy arrangement into stacks of modules as well as the battery cells present on 4 of its different outer surfaces of the battery stack module
[25].
A prismatic electric power cell consisting of 2 current conductors with flat geometry with an arrangement of cells parallel to each other may be constructed. A hole is placed toward the surface, which is created so that the flat current conductor is in mirror symmetry with respect to the other current conductor. This arrangement provides stacking and arrangement of the battery modules to provide suitable energy storage for the electric vehicles
[26]. This patent is currently the most cited invention of Walter Lachenmeier, with citations from companies such as Toyota, BMW, Mitsubishi, Samsung and LG.
A system in which cells are stacked together in series and parallel cell blocks may enhance the current and voltage output of the battery. Here, electric contacts are established by arresters and spacers using clamping devices to reduce the loss of electric energy stored in the batteries and electric devices. Similarly, the spacers are also used between different batteries to improve the electric power output of the batteries
[27].
The connection of the batteries to attain a stack of batteries requires highly efficient battery connectors. A fixed battery connector was described that does not lead to chemical loss during the charging and discharging process. The contact element has at least one receiving chamber main electrode, which is open in one direction in which the contact connector is placed. To attain a compact design, the contact connectors are clamped by heating to make a fixed battery connector
[28].
The manufacturing of a complete lithium-ion battery for use in electric vehicles has been developed in an attempt to create a sealed designed battery to avoid leakage, electric charge drainage and lower battery efficiency. The invented method uses an electrochemical storage cell with a sealing compound, contact element, current collector with conductive material and an energy storage unit. The sealing compounds become solid after the insertion of an energy storage cell (mainly a lithium-ion battery). This creates a protected outer cover for the battery to store charge without the issue of leakage
[29].
The lithium-ion energy storage devices that were manufactured by Li-Tec Battery GmbH and in particular the flexible ceramic separators used were nominated for the German Future Prize 2007.
4. Electric Vehicles and Energy Storage Technologies
Due to his many years of work at DFG, Walter Lachenmeier was well connected to the German research landscape in the field of engineering sciences with a focus on energy technology as well as related disciplines. Following his position at Li-Tec Battery GmbH in battery development, he was offered to participate in a startup electrical car company, e-Wolf GmbH. Walter Lachenmeier was a pioneer in Germany when it came to electrical mobility: forward-looking and—as others tended to brake here—also impatient and relentless. Ten years beyond his retirement age, he still managed to inspire young people with competence and passion. These efforts culminated in presenting an extreme sports car with an all-electric drive in ultra-lightweight design at the 2009 IAA (International Automobile Exhibition, Frankfurt am Main, Germany). The e-Wolf E1 was a joint project of Leichtbauzentrum Sachsen GmbH (LZS), the Institute of Lightweight Engineering and Polymer Technology at Technical University Dresden, e-Wolf GmbH and Li-Tec Battery GmbH. For the first time, this vehicle combined an ultralight chassis made of a carbon aluminum construction with innovative flat cell technology, carbon rims, formula sports technology and road approval
[36]. e-Wolf GmbH received the iF Design Award 2010 for its campaign and multimedia installation at IAA.
The final inventions of Walter Lachenmeier in this field deal with the optimization of the charging process, recuperation of energy, as well as a method for the storage of sustainably produced energy.
An increased efficiency of vehicles to supply energy has been invented using a mechanical energy accumulator (process of conversion of kinetic energy into mechanical energy) to store energy and deliver it back to the vehicle motor. This system provides a strategy to help store energy efficiently and provides energy to the vehicle when necessary
[30].
Charging the battery during the operation of an electric vehicle has been suggested. The charging current is obtained by absorbing the mechanical power generated by the suspension of the motor vehicle, usually known as a shock absorber (recuperation). This system has been claimed to be suitable for use in electric and hybrid cars
[31]. A numerical simulation was conducted for Intertronic Gresser GmbH (Würzburg, Germany) on the recuperation of electrical energy in the shock absorbers. In vehicles with conventional hydraulic or mechanical shock absorbers, energy drawn from the absorption of mechanical vibrations in the vehicle structure is converted into heat energy that cannot be used. However, it is possible to use linear or rotatory generators instead of conventional shock absorbers for recuperation. These can convert the energy generated by mechanical vibrations into electrical energy, which can then be used to charge a battery. The model showed that the technology can produce a significant energy yield, making it an economically viable solution for use in electric or hybrid vehicles
[37].
The final patented invention of Walter Lachenmeier dealt with the storage of energy by a heat accumulator, which may be used to store energy necessitated by grid fluctuations (e.g., due to wind power and solar energy). For example, it can be applied to store energy during the day and make it available at night to charge electric vehicles. Even in the event of a temporary overproduction of “green electricity”, it makes more sense to store it in a more suitable form than to use it only to heat night storage facilities
[38]. The accumulator consists of non-pressurized and pressurized heat exchangers to cool the system down using the counterflow principle. Balls were used as a medium to exchange heat. The heat is moved via the balls, which are guided to the storage tank and reservoir containing the coolant (e.g., water)
[32]. Heat is exchanged through the balls to the reservoirs.
Although Walter Lachenmeier was a strong proponent of electrical vehicles, alternative energy technologies and public transportation systems
[39], he also warned against exaggerated expectations and often nonscientific and physically improbable prognoses, such as “a degree of self-sufficiency in renewable energy of 123% or even 147%” claimed by scientists with industry conflicts of interest
[40][41]. He was also commenting against nonsensical, unscientific claims according to which renewable energies would make electricity supply cheaper
[42]. He also was against bridge technologies such as hydrogen and can be quoted: “This is also not sensible because most of the expensively generated electricity is lost on the way from the water electrolysis to the vehicle tank. Efficiency is absurdly low. Better store electricity directly in a battery”
[43].
5. Public Health Research
The most recent scientific interests of Walter Lachenmeier shifted toward public health issues, possibly facilitated by his own deteriorating health conditions. He had been a strong smoker for most of his life, and his interest in harm reduction also motivated me to investigate comparative risk assessment of electronic cigarettes and heat-not-burn tobacco products
[44][45][46].
We always had a strong scientific exchange in our topics, but when I participated in a 2016 working group meeting of the World Health Organization’s International Agency for Research on Cancer (IARC) on the carcinogenicity assessment of very hot beverage consumption
[47][48], my father became fascinated by this topic and we pooled our resources to conduct a study combining numerical simulation of heat conduction within the oral mucosa and some experimentation using a measuring spoon designed by my father, which allowed the so-far open question regarding threshold contact temperatures to avoid oral burning, which is assumed as underlying mechanism for carcinogenicity, to be answered
[49].
Since the appearance of the still ongoing coronavirus disease 2019 (COVID-19) pandemic at the beginning of 2020, my father has used his modeling expertise to interpret the data, because the official reporting at that time in Germany was less advanced
[50]. As there was a shortage of publicly available face masks, he devised a protocol to make masks at home from sterile triangular cloths widely available in each first-aid kit for cars according to DIN 13168
[51]. My father also had strong opinions about overpriced FFP2 respiratory masks sold to the German state due to the efforts of certain lobbyists
[52]. Taking into account the growing nonscientific debate during the pandemic, culminating in corona deniers and the so-called “Querdenker” (lateral thinkers) movement, Walter Lachenmeier still had the strong belief that physicians, virologists and scientists from other scientific disciplines would be able to develop solutions from their findings
[53]. Actually, my father was right in his belief. Interestingly, the BioNTech mRNA vaccine dates back to a project in a DFG-funded Collaborative Research Center on cancer research in Mainz
[54]. I think my father would have said that this effort has been worth the investment of tax money.
The final paper by my father, which was again a collaboration with me, dealt with the potential to improve sleep quality in patients with severe forms of lung disease by using a low-cost wearable device
[55]. This research was based on the difficulties he himself had to deal with because of his illness, namely being afraid to sleep because one could suffocate at night. He found a simple aid via the Internet and reported on its benefits. What had helped him could and should be available to support other people in similar situations.