New Battery Technologies for eVTOLs: “We are Trying to Figure Out the Limitations”

The Holy Grail with­in the emerg­ing eVTOL indus­try is a major break­through in bat­tery pow­er. To dis­cov­er a new tech­nol­o­gy that can rad­i­cal­ly improve the dura­tion of bat­ter­ies and lessen their need to be con­stant­ly recharged. Who­ev­er makes this quan­tum leap and suc­cess­ful­ly patents it, is look­ing at rich­es beyond imag­i­na­tion.

Typ­i­cal of the verve to find that Grail is U.S Oak Ridge Nation­al Lab­o­ra­to­ry (ORNL) based in Ten­nessee, “where researchers are work­ing on more improved, longer-last­ing bat­ter­ies for eVTOLs,” reports sciencedaily.com. Their aim is “to fig­ure out the lim­i­ta­tions.”

To design this ulti­mate bat­tery, the team is devel­op­ing new ener­gy-dense mate­ri­als and learn­ing how they degrade under extreme con­di­tions. The researchers are also devel­op­ing bat­tery con­trol sys­tems. Not sur­pris­ing­ly, one thing the sci­en­tists have learned so far is that per­for­mance demands for elec­tric air taxis can sig­nif­i­cant­ly reduce their longevi­ty and dura­bil­i­ty.

This means such air­craft can­not rely on the same bat­ter­ies that pow­er a Tes­la Mod­el Y or Chevy Bolt, for exam­ple. That is because EV bat­ter­ies usu­al­ly drain at a steady rate, while eVTOLs require vary­ing amounts of pow­er for dif­fer­ent flight stages like climb­ing, hov­er­ing and descent.

Marm Dix­it

Marm Dix­it, a ORNL lead researcher told sciencedaily.com, “Now we know more about what is required of the eVTOL bat­tery, we’ll need to engi­neer sys­tems dif­fer­ent­ly to achieve that. Our focus is fun­da­men­tal: What hap­pens to the mate­ri­als under these spe­cif­ic loads and oper­at­ing con­di­tions?” Adding, “There­fore, we are try­ing to fig­ure out the lim­i­ta­tions of the bat­tery chem­istry we have now, and then tune the bat­tery to bridge that gap.”

Llias Bel­harouak, an ORNL Cor­po­rate Fel­low who guides the research, remarked, “The eVTOL pro­gram presents a unique oppor­tu­ni­ty for cre­at­ing a brand new type of bat­tery with very dif­fer­ent require­ments and capa­bil­i­ties than what we have seen before. This requires us to answer ques­tions about the inter­play of bat­tery safe­ty, cycle life and sta­bil­i­ty at high tem­per­a­tures, while bal­anc­ing the need for short bursts of high pow­er with ener­gy reserves for longer-range flight.”

The first major take­away from the study is that the pow­er and per­for­mance demands for eVTOL bat­ter­ies can sig­nif­i­cant­ly reduce their longevi­ty and dura­bil­i­ty.

“The team made lithi­um-ion bat­ter­ies at the DOE Bat­tery Man­u­fac­tur­ing Facil­i­ty locat­ed at ORNL and ran them through sim­u­lat­ed climb stages of eVTOL air­craft,” writes sciencedaily.com. “Sci­en­tists stud­ied what hap­pened inside the bat­tery dur­ing cycling, includ­ing how much ener­gy was rapid­ly acces­si­ble dur­ing the demand­ing take­off phase, then test­ed the bat­tery mate­ri­als after­ward for cor­ro­sion and oth­er chem­i­cal or struc­tur­al changes.”

The web­site goes on, “Sys­tem­at­ic inves­ti­ga­tion link­ing actu­al flight pro­files to real-time phys­i­cal bat­tery oper­a­tion is rare. How­ev­er, it is key ground­work for devel­op­ing new bat­tery chemistries to achieve safe flight per­for­mance. The study incor­po­rates test­ing of a new ORNL-devel­oped elec­trolyte, a mate­r­i­al through which elec­trodes exchange ions against the cur­rent state-of-the art ver­sion used in lithi­um-ion bat­ter­ies. Using the eVTOL mis­sion pro­files, the ORNL elec­trolyte per­formed bet­ter, retain­ing more capac­i­ty dur­ing the most pow­er-demand­ing flight phas­es.”

Dix­it points out, “Your bat­tery is not just capac­i­ty at the end of 1,000 cycles. It’s what’s hap­pen­ing with­in a cycle that tells you whether your sys­tem is going to work or crash. And the stakes are much high­er here because you’re ask­ing how safe it is to go up in the air. This is a ques­tion we don’t know the answer to… yet.”

Ener­gy Stor­age Area at Oak Ridge Lab­o­ra­to­ry

What dri­ves researchers on toward the Holy Grail is also, of course, glob­al cli­mate change. “There is a strong incen­tive,” con­tin­ues Dix­it, “as dur­ing a peri­od of such change, eVTOLs can help curb plan­et-warm­ing. At present, the glob­al trans­porta­tion sec­tor is respon­si­ble for con­tribut­ing 14 per­cent of all air pol­lu­tion.” One recent study found that only 10 coun­tries and ter­ri­to­ries out of 134 are meet­ing air-qual­i­ty stan­dards.

The cur­rent Ten­nessee research is one of many strate­gies aimed at green­ing up air trans­port. For instance, anoth­er group of sci­en­tists are work­ing on a new gen­er­a­tion of bio­fu­els to pow­er planes that may con­tribute sig­nif­i­cant­ly less harm­ful pol­lu­tion to the atmos­phere.

Mean­while, a grow­ing num­ber of major air­lines, includ­ing Amer­i­can, Delta, and Unit­ed, have pledged to achieve net-zero car­bon pol­lu­tion by 2050.

(News Source: www.sciencedaily.com)

(Images: Oak Ridge Lab­o­ra­to­ry)

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