© Ulrike Wunderwald / Fraunhofer IISB

Alu­minum-ion bat­ter­ies as an alter­na­tive stor­age tech­nol­o­gy for sta­tion­ary applications

In the ALBATROS project, a con­sor­tium from research and indus­try is fur­ther devel­op­ing the alu­mini­um-ion bat­tery (AIB). The focus is on the process­es in the bat­tery cell and at the inter­faces between elec­trodes and elec­trolyte. Alu­minum-ion bat­ter­ies have a high poten­tial in terms of safe­ty, cycle sta­bil­i­ty and charge rate. Alu­minum-ion tech­nol­o­gy also offers advan­tages in terms of pro­duc­tion costs, raw mate­r­i­al avail­abil­i­ty and recy­cling. Con­sor­tium part­ners in the ALBATROS bat­tery project are Fraun­hofer IISB, IoLiTec GmbH, DECHEMA Research Insti­tute and the Insti­tute of Inor­gan­ic Chem­istry at the Tech­ni­cal Uni­ver­si­ty Bergakademie Freiberg.

The con­sor­tium in the ALBATROS project is focus­ing on a sub­stan­tial fur­ther devel­op­ment of the alu­mini­um-ion bat­tery. The acronym stands for “Alter­na­tive mate­r­i­al sys­tems for sta­tion­ary bat­tery stor­age based on alu­mini­um as anode mate­r­i­al for the sub­sti­tu­tion of crit­i­cal raw mate­ri­als”. The aim of the project is to cre­ate a com­pre­hen­sive basic under­stand­ing of the process­es in the bat­tery cell and in par­tic­u­lar at the inter­faces between elec­trodes and elec­trolyte. The nov­el alu­minum-based cell chem­istry has promis­ing poten­tial in terms of safe­ty, cycle sta­bil­i­ty and charge rate. Par­tic­u­lar­ly rel­e­vant here is the avoid­ance of crit­i­cal raw mate­ri­als, such as lithi­um, nick­el or cobalt. With­in the ALBATROS project, Fraun­hofer IISB (Erlan­gen / Freiberg), IoLiTec GmbH (Heil­bronn), the DECHEMA Research Insti­tute (DFI, Frank­furt am Main) and the Insti­tute of Inor­gan­ic Chem­istry at the Tech­ni­cal Uni­ver­si­ty Bergakademie Freiberg are work­ing togeth­er. The ALBATROS project is fund­ed by the Fed­er­al Min­istry of Edu­ca­tion and Research (BMBF).

A sig­nif­i­cant increase in demand is fore­cast for sta­tion­ary elec­tri­cal stor­age. It can already be seen today that this strong growth can­not be cov­ered by con­ven­tion­al bat­tery tech­nolo­gies. Par­tic­u­lar­ly with regard to the crit­i­cal raw mate­ri­als used to date and the costs of bat­tery stor­age, alter­na­tives to the estab­lished cell chemistries are need­ed in the near future. One promis­ing option is the alu­minum-ion bat­tery (AIB). The first func­tion­al sam­ples have already been pre­sent­ed at the Tech­nol­o­gy Cen­ter for High Per­for­mance Mate­ri­als (THM) of Fraun­hofer IISB in Freiberg (see info links).

Com­pared to lead-acid or Li-ion bat­ter­ies, alu­minum-ion tech­nol­o­gy offers sig­nif­i­cant advan­tages, espe­cial­ly in terms of man­u­fac­tur­ing costs and raw mate­r­i­al avail­abil­i­ty. But also in terms of haz­ard poten­tial and recy­cla­bil­i­ty, alu­mini­um-ion bat­ter­ies can be a thor­ough­ly con­vinc­ing alter­na­tive due to the use of non-flam­ma­ble electrolytes.
Inex­pen­sive alu­mini­um and graphite can be used as elec­trode mate­ri­als for the AIB. The elec­trolytes are based on so-called ion­ic liq­uids and, in inter­ac­tion with the oth­er mate­ri­als, make the reversible charg­ing process of the alu­mini­um-ion bat­tery pos­si­ble in the first place. With the very high cycle sta­bil­i­ty of more than 20,000 cycles and charge rates of more than 150 C, fur­ther devel­oped alu­mini­um-graphite sys­tems hold enor­mous poten­tial for future appli­ca­tions. The non-flam­ma­bil­i­ty of the com­po­nents and the elec­trolyte makes the AIB a safe stor­age option, for exam­ple for elec­tric­i­ty from fluc­tu­at­ing renew­able ener­gy sources.

How­ev­er, fur­ther sci­en­tif­ic pre­lim­i­nary work is required before the AIB can be launched on the mar­ket. A par­tic­u­lar chal­lenge here is the high­ly cor­ro­sive behav­iour of the elec­trolytes pre­vi­ous­ly used in AIB. Before appli­ca­tion-rel­e­vant pro­to­type cells are avail­able for test­ing, exten­sive mate­r­i­al qual­i­fi­ca­tion, test­ing and cer­ti­fi­ca­tion must be car­ried out. For the the­o­ret­i­cal foun­da­tion of the nov­el cell chem­istry, the sci­en­tists con­cen­trate on the basic chem­i­cal mech­a­nisms and mate­r­i­al-spe­cif­ic influ­enc­ing vari­ables. Among oth­er things, the kinet­ic para­me­ters of alu­mini­um dis­so­lu­tion and depo­si­tion on the alu­mini­um anode are inves­ti­gat­ed for dif­fer­ent elec­trolyte com­po­si­tions. Like­wise, the focus is on the input and out­put of charge car­ri­ers into and out of the graphite matrix. This also includes spe­cif­ic analy­ses of the species of the charge car­ri­ers. Anoth­er focus is the inves­ti­ga­tion of self-dis­charge process­es. This effect is of par­tic­u­lar inter­est for lat­er applications.

The knowl­edge gained is the indis­pens­able basis for the design, fur­ther devel­op­ment and opti­mi­sa­tion of appli­ca­tion-ori­ent­ed and sus­tain­able AIB stor­age sys­tems. Here, as a real­is­tic first step, an appli­ca­tion in sta­tion­ary elec­tri­cal stor­age sys­tems is aimed at. Thus, the alu­minum-ion bat­tery can be an essen­tial build­ing block for the expan­sion of urgent­ly need­ed stor­age capac­i­ties and con­tribute to the suc­cess of the ener­gy tran­si­tion. The ALBATROS project makes ele­men­tary con­tri­bu­tions to the real­iza­tion of effi­cient, durable, cost-effec­tive, envi­ron­men­tal­ly com­pat­i­ble and eas­i­ly recy­clable bat­tery components.

The ALBATROS project is fund­ed by the Fed­er­al Min­istry of Edu­ca­tion and Research (BMBF).

Fraun­hofer THM

The Fraun­hofer Tech­nol­o­gy Cen­ter for High Per­for­mance Mate­ri­als THM is a research and trans­fer plat­form of the Fraun­hofer Insti­tute for Inte­grat­ed Sys­tems and Device Tech­nol­o­gy IISB and the Fraun­hofer Insti­tute for Ceram­ic Tech­nolo­gies and Sys­tems IKTS. With­in the frame­work of indus­tri­al orders and pub­licly fund­ed projects, semi­con­duc­tor and ener­gy mate­ri­als are joint­ly trans­ferred into new appli­ca­tions, with spe­cial con­sid­er­a­tion of future mate­r­i­al recy­cling. One focus of the work at Fraun­hofer THM is the analy­sis and devel­op­ment of sus­tain­able bat­tery sys­tems with improved life cycle assess­ment and raw mate­r­i­al avail­abil­i­ty com­pared to estab­lished bat­tery technologies.

Fraun­hofer IISB

Intel­li­gent pow­er elec­tron­ic sys­tems and tech­nolo­gies — this is the mot­to under which the Fraun­hofer Insti­tute for Inte­grat­ed Sys­tems and Device Tech­nol­o­gy IISB, found­ed in 1985, con­ducts applied research and devel­op­ment for the direct ben­e­fit of indus­try and soci­ety. With sci­en­tif­ic exper­tise and com­pre­hen­sive sys­tems know-how, it sup­ports cus­tomers and part­ners world­wide in trans­lat­ing cur­rent research results into com­pet­i­tive prod­ucts, for exam­ple for elec­tric vehi­cles, avi­a­tion, pro­duc­tion and ener­gy supply.

The insti­tute bun­dles its activ­i­ties in the two busi­ness units Pow­er Elec­tron­ic Sys­tems and Semi­con­duc­tors. In doing so, it com­pre­hen­sive­ly cov­ers the entire val­ue chain from basic mate­ri­als to semi­con­duc­tor com­po­nent, process and mod­ule tech­nolo­gies to com­plete elec­tron­ics and ener­gy sys­tems. As a unique Euro­pean com­pe­tence cen­ter for the semi­con­duc­tor mate­r­i­al sil­i­con car­bide (SiC), IISB is a pio­neer in the devel­op­ment of high­ly effi­cient pow­er elec­tron­ics, even for extreme require­ments. With its sys­tems, IISB repeat­ed­ly sets bench­marks in ener­gy effi­cien­cy and per­for­mance. Through the inte­gra­tion of intel­li­gent data-based func­tion­al­i­ties, new appli­ca­tion sce­nar­ios are con­tin­u­ous­ly being developed.

IISB has around 300 employ­ees. The main loca­tion is in Erlan­gen, anoth­er loca­tion is at the Fraun­hofer Tech­nol­o­gy Cen­ter for High Per­for­mance Mate­ri­als (THM) in Freiberg. The insti­tute coop­er­ates close­ly with the Friedrich-Alexan­der-Uni­ver­si­ty Erlan­gen-Nurem­berg (FAU) and is a found­ing mem­ber of the Ener­gy Cam­pus Nurem­berg (EnCN) as well as the Per­for­mance Cen­ter Elec­tron­ic Sys­tems (LZE). IISB coop­er­ates with numer­ous nation­al and inter­na­tion­al part­ners in joint projects and associations.