C/Si Composite Anodes for Advanced Lithium Ion Batteries

NASA Battery WorkshopHuntsville, AL Nov. 18, 2009C/Si Composite Anodes for AdvancedLithium Ion BatteriesJohn Olson, Dean Recla, Trudy Scholten and Steve DietzTDA Research303-261-1122jolson@tda.comTDAR e s e a r c h

OUTLINE• Introduction to TDA Research• Technical Approach• Results– Capacity–Power– Irreversible capacity– Capacity fade• Future WorkTDAR e s e a r c h

TDA Research, Inc.www.tda.comWheat Ridge Facility22,500 ft 2 offices and labsSynthetic ChemistryCatalyst/Sorbent Synthesis/TestingCeramics ProcessingMachine and Electronics ShopsSEM (w/EDX), TOF Mass SpecGolden Facility27,000 ft 2 offices and labs27 fume hoodsSynthetic ChemistryCatalytic Process DevelopmentPilot Scale ProductionTDAR e s e a r c h

Goal Oriented ResearchPrivate, founded in 1987~ $12.5 million/year revenue in 2008Staff of 81, primarily il chemists andengineers, 2/3 of whom haveadvanced degrees (24 w/ Ph.D.)Commercial Products• SulfaTreat DO• Fullerenes• Conducting Polymers• Self-Heating Products• Sulfur Sorbents• Carbon Electrodes for DesalinationTDAR e s e a r c h

History of Commercial SuccessTDA’s business plan is to develop new technologies andlicense them to leading industrial companies•142 SBIR Phase IIs• Of 107 completed, 87have had Phase III fundingor sales• ~ $91.5 million in PhaseIII funding• Over $11.3 million indirect sales; ~$28.2 millionof licensed customer salesProprietary – TDA ResearchTDAR e s e a r c h

Activated Carbons for Ultracapacitors• PI: Dr. Steven Dietz• Low-cost production from sugar precursors• Larger voltage window than current carbons;2.85 V vs 2.7 VCapture regenerative brakingenergy in hybrid and fuel cellvehiclesLoad level in cars and electronic,reducing wear on the battery,improving power system stabilityand reducing weight• Faster charge / discharge (lower internalresistance)• Tailored pores allow liquid access to all thecarbon’s surface area• Joint development agreement forultracapacitors with MeadWestvaco• Under evaluation by Maxwell Technologiesand othersDevelopment funded by DOE, NSFProprietary – TDA ResearchTDAR e s e a r c h

Engineered Pore-SizeOptimizes PerformanceProprietary – TDA ResearchTDAR e s e a r c h

Key Personnel Are Experienced• Dr. John Olson – PI, Electrochemist– Joined TDA Research in 2007– 15 years experience in battery industry; OptimaBatteries, Boundless Corp.– Lithium-ion, VRLA, Ultracapacitors, batterymanagement, charge algorithms– 3 patents• Dr. Steve Dietz – Carbon Synthesis– Invented pore size engineering of activated carbons– Applied to ultracapacitors and capacitive de-ionization– TDA scientist from 1993– 4 patents, 1 patents pendingTDAR e s e a r c h

Silicon as an Anode• 4200 mAh/g capacity (theoretical)• Li forms alloy, rather than intercalatingti• 4.4 Li atoms per Si atom• Large expansion 280%• Cycling leads to rapid capacity loss due tocracking and loss of conductive matrixTDAR e s e a r c h

Efforts to Engineer Silicon forLi-Ion Battery Anodes• Nanoscale particle size – effectively extendslife, but Oswald ripening and agglomerationlead to capacity fade and high surface arearesults in SEI formation and largeirreversible capacity loss• Graphite carbon matrix or coatings– alsoeffective, but capacity fade still needsimprovement and SEI growth an issueTDAR e s e a r c h

Si/C Composites+ xLi+-xLi +SiLi x SiHard carbon matrix with encapsulated silicon• Prevent SEI layer formation/re-formation on Si particles• Provide highly conductive matrix• Prevent agglomeration of dispersed Si particlesProprietary – TDA ResearchTDAR e s e a r c h

Hard d( (non-graphitizable)Carbon vs Graphites• Higher specific capacity and better chargeacceptance• Lower energy density• Better cycle life, less volume change and morestable SEI layer• Higher irreversible capacity due to surface groupsand water adsorption• Higher surface area leading to increased SEIformation• Hydrogen incorporation causes cycling hysterisisTDAR e s e a r c h

Synopsis of Work EffortThere were three major factors studied:(1) Composites fired at differenttemperatures (> 1200 C or 1000 C)(2) Composites made with nano Si versus44 um Si particle sizes(3) Composites using different carbonsourcesTDAR e s e a r c h

Experimental Test Methods• Anode formulation: 87.5% active, 5% Super P, 5%PVDF in NMP cast onto Cu foil (25 um)• Half 2025 cells: Li foil, Celgard separator, 1 M LiClO 4EC:DEC 1:1 (Dahn charge method)• Full 2025 cells: Commercial LiNi 0.8 Co 0.2 O 2 cathode,Celgard separator, 1 M LiClO 4 EC:DEC 1:1• Typical charge/discharge rates: C/2 – C/4• Resistance measurements using current pulse at 20 ms• Irreversible capacity expressed as Ah charge /Ah dischargeTDAR e s e a r c h

Started with Control CarbonsFired at 1200 – 1400 CCycle 1200 1300 1400 CommercialDensity (g/ml) 0.645 0.594 0.683 0.691BET (m 2 /g) 0.69 0.42 0.14Capacity 1st 375 512 Bad data 566(mAh/g) 2nd 379 471 5453rd 371 442 5784th 387 384Capacity 1st 244 304 325(mAh/ml) 2nd 238 280 3133rd 248 262 3324th 260 228Irrev. Capa1st 131 125(%) 2nd 103 105 1033rd 104 100 1044th 103 102TDAR e s e a r c h

C/Si Composites Fired at 1300 CWere InactiveSiCSiSiSiCSiCSiSiSiSi1300 C 1000 CSiC formed at 1300 C, but not at 1000 CTDAR e s e a r c h

Process Conditions Changed toReduce Surface Areas450400350a (m2/g)Surface Are3002502001501005000 2 4 6 8 10 12 14 16Sample (#)TDAR e s e a r c h

Initial C/Si-nano Compositeshad Relatively Low CapacitiesSample mAh/g mAh/ml % SiSO26 618 147 20SO27 545 140 20So we evaluated some Si anodecontrolsTDAR e s e a r c h

Initial Si-nano Controls AlsoShowed Low CapacityCapacity400035003000Capacity (m mAh/g)2500200015001000Si nanoSi 325 mesh50001 2 3 4 5Cycle (#)TDAR e s e a r c h

C/Si Composites With 44 um SiParticles Showed Good CapacitySample mAh/g mAh/ml %SiSO32 1080 305 20SO36 1510 595 40SO38 1270 500 40But high capacity fade!TDAR e s e a r c h

Dispersion of NanoSi Resultedin Theoretical CapacityCapacity450040003500Capacity (mA Ah/g)30002500200015001000500Si nanoSi 325 meshSi disp nano01 2 3 4 5Cycle (#)TDAR e s e a r c h

Evaluated a Second Sugar Sourceto Obtain Better Dispersion44 um SiSample mAh/g mAh/ml Carbon Source % Si32 1080 305 Type 1 2043 1060 436 Type 2 2044 993 426 Type 2 20Nano SiSample mAh/g mAh/ml Carbon Source % Si26 618 147 Type 1 2027 545 140 Type 1 2040 656 273 Type 2 20Only capacities were about the sameTDAR e s e a r c h

Carbon Stabilized Si CapacityCapacity Fade120100pacity (%)Normalised Ca80604020323638434445Si 325 mesh01 2 3 4 5Cycle (#)TDAR e s e a r c h

Carbon Also Stabilized Si-nanoCapacity Fade120110Normalized Capacity (%)100908070262740Disp. Si nanoSi nano601 2 3 4 5Cycle (#)TDAR e s e a r c h

Type 2 Carbon Has BetterCapacity Fade Than Type 1110105Normalized Capacity (%)10095908580533344275701 2 3 4 5Cycle (#)TDAR e s e a r c h

Irreversible Capacities areVariable, but Encouraging240C/Si nano220200Irreversible Capacity(%)18016044 um C/Si Carbons14012010032 36 38 43 44 45 Type 1 Type 2 Com 26 27 40SampleTDAR e s e a r c h

Power is Dependent onLoading Level of SiRf vs DOD7060Rf (o ohm)5040302020%40%40%20% (2)20% (2)0%10044 um Si0 20 40 60 80 100 120DOD (%)C/44 um SiTDAR e s e a r c h

Type 2 Carbon Also SlightlyBetter for Power7060Resistan nce (ohm)5040302020% Type 120% Type 120% Type 20% Type 10% Type 21000 20 40 60 80 100 120DOD (%)C/Si nanoTDAR e s e a r c h

Cycle Life Will Be Focus ofFuture Effort120010008006000%0%20%20%40%40%TDAR e s e a r c hCapacity (Ah/g)400200017414722029336643951258565873180487795010231096116912421315138814611534Cycle (#)

Resistance Increase NotExcessive0% Si 20% Si3545304025352030Rdis (ohm m)151050-5-100 20 40 60 80 100 120Rdis (oh m)25201510500 20 40 60 80 100 120DOD (%)DOD (%)TDAR e s e a r c h

Economic Analysis FavorsLarger Particle Size Si44 um Si Nano Si($/kg) ($/kg)Materials Cost 82 8.2 202.4Production Cost 17.7 211.9TDAR e s e a r c h

Future Effort• Optimize firing temperature and conditions• Obtain better dispersion of Si particles in sugarprecursors• Evaluate Si particles size between 44 um andNano (performance vs. economics)• Evaluate carbon coatings to deactivate surfaceactivity and extend life• Scale up production to pilot plant (kg) levels• Produce commercial prototype cells for deliveryand testTDAR e s e a r c h

Thanks to NASA JSC for FundingNASA Phase I SBIRContract #: NNX09CE58PCOTR: Judy JeevarajanThank You for Your InterestTDAR e s e a r c h