DLR: Bet­ter dig­i­ti­za­tion meth­ods for the devel­op­ment of bat­ter­ies of the future

Bat­tery tech­nolo­gies are now used in all mobile appli­ca­tions on land, air and sea. Con­ven­tion­al lithi­um-ion bat­ter­ies based on liq­uid elec­trolytes are con­tin­u­ous­ly opti­mized, but are reach­ing their phys­i­cal lim­its in terms of ener­gy and pow­er stored per vol­ume. Sol­id-state bat­ter­ies are a pos­si­ble alternative.

Since Novem­ber 2021, the joint project Theo­Dat in the com­pe­tence clus­ter for sol­id-state bat­ter­ies “Fes­t­Batt” of the Fed­er­al Min­istry of Edu­ca­tion and Research has entered its sec­ond fund­ing phase.

Sol­id State Batteries

Sol­id-state bat­ter­ies are a promis­ing con­cept for the fur­ther devel­op­ment of cur­rent­ly avail­able bat­ter­ies. They are very sim­i­lar to con­ven­tion­al lithi­um-ion bat­ter­ies with liq­uid elec­trolyte and dif­fer from them main­ly in that a sol­id elec­trolyte or “sol­id elec­trolyte” for short, usu­al­ly a ceram­ic mate­r­i­al, is used instead of the liq­uid electrolyte.

This dif­fer­ence includes sev­er­al advan­tages: Sol­id-state bat­ter­ies have high­er long-term stor­age capac­i­ties, short­er charg­ing times, are lighter and sig­nif­i­cant­ly small­er, and offer greater safe­ty because inter­nal short cir­cuits and the result­ing induced fires are much eas­i­er to avoid than with con­ven­tion­al lithi­um-ion batteries.

A num­ber of sci­en­tif­ic and tech­no­log­i­cal chal­lenges remain to be solved for the com­mer­cial suc­cess and mass pro­duc­tion of sol­id-state bat­ter­ies. This is where the Fes­t­Batt com­pe­tence clus­ter, which is fund­ed by the Ger­man Fed­er­al Min­istry of Edu­ca­tion and Research (BMBF) and whose first fund­ing phase involved more than 100 researchers from var­i­ous research insti­tu­tions, comes in. Fes­t­Batt is coor­di­nat­ed by Prof. Dr. Jür­gen Janek from the Cen­ter for Mate­ri­als Research at Jus­tus Liebig Uni­ver­si­ty Giessen. The project is part of the umbrel­la con­cept “Research Fac­to­ry Bat­tery” of the Fed­er­al Min­istry of Edu­ca­tion and Research (BMBF), which aims to secure Ger­many’s tech­no­log­i­cal sov­er­eign­ty in bat­tery technology.

In a first step, the sci­en­tif­ic fun­da­men­tals of the mate­r­i­al sys­tems of sol­id elec­trolytes as core com­po­nents of sol­id-state bat­ter­ies were suc­cess­ful­ly elab­o­rat­ed. The focus of the sec­ond phase is now on the devel­op­ment of cell con­cepts and entire sol­id-state bat­tery cells based on these elec­trolytes and the nec­es­sary mate­r­i­al and process tech­nol­o­gy. To this end, the BMBF is con­tin­u­ing its fund­ing of the “Fes­t­Batt” com­pe­tence clus­ter from Novem­ber 2021 with a total of around 23 mil­lion euros for three years. A total of 17 sci­en­tif­ic insti­tu­tions — includ­ing uni­ver­si­ties, Helmholtz cen­ters and insti­tutes of the Fraun­hofer Soci­ety and the Max Planck Soci­ety — are involved in the com­pe­tence cluster.

The­o­ry and Data Plat­form (FB2-Theo­Dat)

In the sec­ond phase, the “Fes­t­Batt” com­pe­tence clus­ter con­sists of nine col­lab­o­ra­tive projects. This also includes the joint project FB2-TheoDat.

In the joint project “The­o­ry and Data”, state-of-the-art sim­u­la­tion and dig­i­ti­za­tion tech­niques are being devel­oped specif­i­cal­ly for sol­id-state bat­ter­ies with the aim of devel­op­ing new cell con­cepts and sig­nif­i­cant­ly accel­er­at­ing their design, always in close coop­er­a­tion with the oth­er plat­forms of the com­pe­tence cluster.

As part­ners of the Theo­Dat plat­form, the TU Munich, the DLR, the TU Darm­stadt, the Karl­sruhe Insti­tute of Tech­nol­o­gy (KIT) and the West­phalian Wil­helms Uni­ver­si­ty of Mün­ster are pool­ing their exper­tise across the entire sim­u­la­tion chain from the atom­istic to the cel­lu­lar scale. State-of-the-art data sci­ence meth­ods will be incor­po­rat­ed to cre­ate a vir­tu­al research infra­struc­ture for sol­id-state bat­ter­ies. The joint project FB2-Theo­Dat is coor­di­nat­ed by Pro­fes­sor Dr. Arnulf Latz, Ger­man Aero­space Cen­ter (DLR) e.V..

Dig­i­tal design tools are essen­tial for accel­er­at­ing the devel­op­ment of new mate­r­i­al- and appli­ca­tion-spe­cif­ic bat­tery cell con­cepts. For this pur­pose, mate­r­i­al-spe­cif­ic math­e­mat­i­cal mod­els must be devel­oped. These have the abil­i­ty to real­is­ti­cal­ly rep­re­sent in the com­put­er oper­a­tional­ly rel­e­vant prop­er­ties of the sol­id elec­trolytes used and the process­es that occur dur­ing the oper­a­tion of sol­id-state bat­ter­ies. This requires close cou­pling of atom­istic mate­r­i­al mod­els, com­plex cell mod­els, and data sci­ence approach­es. This guar­an­tees the links with the exper­i­men­tal work with­in the sec­ond fund­ing phase of FestBatt.

Physic­o­chem­istry-based mod­els are com­bined with math­e­mat­i­cal tech­niques for ana­lyz­ing large data sets, such as arti­fi­cial intel­li­gence tech­niques. This cre­ates a vir­tu­al research envi­ron­ment that can be used to eval­u­ate dif­fer­ent cell con­cepts through sim­u­la­tion and data analy­sis. In the medi­um term, this will enable a sig­nif­i­cant accel­er­a­tion of devel­op­ment cycles and a reduc­tion in the devel­op­ment costs of sol­id-state batteries.

To achieve this ambi­tious goal, nov­el struc­tural­ly resolved bat­tery cell mod­els are being devel­oped in col­lab­o­ra­tion between DLR and TU Munich. They will map process­es respon­si­ble for both aging and degra­da­tion and the achiev­able pow­er and ener­gy den­si­ty of bat­ter­ies. Atom­istic sim­u­la­tions from the TU Darm­stadt and the Uni­ver­si­ty of Mün­ster are used to inves­ti­gate mate­r­i­al-spe­cif­ic issues of the exper­i­men­tal plat­forms as well as to deter­mine para­me­ters for the cell mod­els. For the para­me­ter­i­za­tion of the cell mod­els, state-of-the-art math­e­mat­i­cal tech­niques are used at the TU Munich, which can extract miss­ing mod­el para­me­ters from het­ero­ge­neous exper­i­men­tal data. All infor­ma­tion will be col­lect­ed in a data­base, which togeth­er with addi­tion­al analy­sis tech­niques will be cre­at­ed in the form of a struc­tured data and vir­tu­al research infra­struc­ture at KIT.

Based on the suc­cess­ful mate­ri­als-ori­ent­ed pre­lim­i­nary work from the first phase of Fes­t­Batt, this will pro­vide the tools for sim­u­la­tion-based devel­op­ment of com­plex cell designs by com­bin­ing com­put­er sim­u­la­tions and data analy­sis techniques.