TECHNOLOGY AREAS: Materials/Processes, Electronics, Weapons

ACQUISITION PROGRAM: Office of Naval Research Code 352: Railgun Innovative Naval Prototype (INP)

OBJECTIVE: To develop electrochemical materials for high density Li-ion batteries capable of supporting high transient and pulsed loads while offering enhanced safety and lifecycle performance.

DESCRIPTION: Future Navy applications will require large amounts of stored energy to support loads which have high discharge and transient characteristics including pulses and similar waveforms. A wide variety of coordinated equipment may be employed to support performance requirements, and lithium-ion batteries are a technology which will likely be part of an energy storage module to support these loads. Current state-of-the-art Lithium-ion energy storage devices extensively utilize energetic metal oxides and flammable electrolytes as a cornerstone for maximizing energy content and providing optimal volumetric and gravimetric densities. These designs provide concern for both safety and cycle life, particularly under high-rate operations.

In order to provide the highest performance, most of the current battery chemistries rely on somewhat unstable cathode materials that can undergo runaway reactions and provide their own source of oxygen in the event of a modest temperature rise, due to something such as an internal cell short. Research into advanced electrode materials that do not contribute oxygen or a significant exotherm under a cell failure scenario, while at the same time maintaining the high energy and power density potential that Li-Ion batteries can provide are needed. Materials such as Lithium Iron Phosphate, which appears to offer abuse safety advantages versus "hotter" cathode materials such as Lithium Cobalt Oxide, also provide an electrochemical penalty in reduction potential, thus decreasing overall energy of the battery. Thus, materials that offer safety while also offering higher operational voltages and long-term stability are desired.

Innovative R&D is needed to investigate alternative cathode materials that limit the potential for energetic failure in a cell, while also offering high rate discharge performance over a large number of cycles. The intent of this solicitation is to produce advanced materials which overcome some of the typical tradeoffs which may effect operational voltage, energy content, etc. In order to enable widespread utilization of highly dense power and energy storage, advanced technologies must embody designs that are scalable/flexible and have robust design to be applicable to a variety of energy storage requirements with varying bias. These materials should offer long life, and allow a significant number of cycles to be obtained both under pulsed and continuous high-rate deep discharge operations. In the case of the use of dopants to effect cathode characteristics, material migration and agglomeration over long-term use must be addressed with respect to safety and performance.

Specifically, this solicitation requests the following characteristics for a lithium-ion battery cathode material:
- Average voltage: >4.0V
- Gravimetric capacity: >180mAh/g
- Cycle life: >2000 deep cycles with >80% original capacity
- Cycle life: >10000 pulse discharges @ 10C or higher within range of 25-75% SOC with >80% original capacity
- Suitable for combination with current and future anode and electrolyte materials
- Scalable to cells with >25Ah capacity
- Suitable in batteries with discharge ranging from 5C to 10C or higher and charge rate up to 10C
- Minimum onset of thermal runaway: 290�C
- Maximum exothermic release @ heating to < 900�C: 150J/g
- Low impedance with minimal growth over cycles and time at elevated SOC and temperature
- Cost in range with current SOA materials including NCA, NCM and LiFePO4

The Navy will only fund proposals that are innovative address R&D and involve technical risk.

PHASE I: The offeror will determine the feasibility of the cathode materials selected via the production of small-scale cells suitable for use as proof-of-concept. Electrochemical and calirometric analysis must be performed to determine and validate the suitability of the material for Li-ion battery application.

PHASE II: The offeror will produce cells of form/capacity no less than a 26650 Li-ion cell, for evaluation. Cell geometry may include jelly roll, pouch cell or other designs. Evaluation of these cells will be performed including validation of cycle life, capacity, thermal behavior and stability of operation at temperatures up to 60�C. These cells will also be combined into modules of 24-48VDC, and evaluated in the same way. The offeror will build multiple battery modules and expose them to a variety of abusive conditions in accordance with NAVSEAINST 9310. The offeror will produce and fine-tune the requirements for a battery management system for operation of these Li-ion battery modules, both separate and in series with others.

PHASE III: The offeror will apply the knowledge gained in phase II to build a complete 1000VDC string of batteries, including BMS, and characterize its performance at a range of charge and discharge rates as described in the solicitation.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Successful development of safe high voltage cathode materials will enable a new generation of lithium-ion battery technology, which offers greater safety and designs which encompass larger quantities of stored energy, and higher discharge performance. Such materials will offer utility in applications ranging from small consumer electronics through automobiles, and also in commercial/capital equipment supporting frequency regulation, load leveling and renewable energy.

REFERENCES:
1. C. Winchester, et al, "Lithium battery Safety: Good Batteries Gone Bad" 2005 Joint Service Power Expo, May 2-5, 2005.

2. A. Manthiram, "Phospho-Olivine Cathodes for Lithium-Ion Batteries". The Electrochemical Society Interface, Spring 2009.

3. K. Smith, Gi-Heon Kim, and A. Pesaran, "Modeling of Nonuniform Degradation in Large-Format Li-ion Batteries" www.nrel.gov/vehiclesandfuels/energystorage/pdfs/46041.pdf.

KEYWORDS: Lithium-ion; battery; cathode; pulsed power; safety; energy storage

Questions may also be submitted through DoD SBIR/STTR SITIS website.