High Energy Li-ion Cells Based on CAM-7 Cathode Material
(submitted to Secondary Lithium Batteries/Lithium-Ion Batteries session of 47th Power Sources
Conference for oral presentation)
Jane Rempel, David Ofer, Adrian Pullen, Daniel Kaplan, Brian Barnett, and Suresh Sriramulu
CAMX Power, 35 Hartwell Avenue, Lexington, MA 02421
e-mail: suresh@camxpower.com, phone: (781)879-1240
Li-ion batteries are attractive for many DoD applications owing to their excellent combination of
energy and life. However, Commercial-Off-The-Shelf (COTS) Li-ion cells still do not offer high
enough energy density (both volumetric – Wh/L and gravimetric – Wh/kg) to enable the mission
profiles and durations desired for many current and anticipated DoD applications. To a large
extent, the cathode material in a Li-ion cell limits the achievable energy density. LiCoO2 cathode
material is predominantly used in COTS high energy density Li-ion cells. The past two decades
have seen a steady increase in the energy density of Li-ion cells with LiCoO2 cathode material
through a combination of improved cell engineering, cathode morphology, and even cathode
charge voltage. However, cell manufacturers have exhausted the cell energy increases possible
with LiCoO2; further increases can come only from new cathode materials. Although COTS cells
with LiNi(1-x-y)MnxCoyO2 (NMC) or LiNi0.80Co0.15Al0.05O2 (NCA) cathode materials are available,
these cells typically have lower energy density than cells with LiCoO2-based cathodes.
Recognizing this need for cathode materials that can enable higher energy density cells, CAMX
Power has been developing a "stabilized" LiNiO2-based cathode material, CAM-7, that combines
high capacity and high average discharge voltage with excellent high rate capability and long life.
In a materials development effort spanning more than 10 years, CAMX Power has resolved the
challenges historically associated with high-nickel LiNiO2 materials such as synthesis
reproducibility, electrode slurry stability, high-temperature cycle life, and thermal stability.
CAM-7 is now being commercialized for several civilian applications worldwide. Production of
this material is being scaled up to 50 metric tons per year in our pilot plant located in Rowley,
MA, and we are collaborating with scale-up partners to produce this material at much larger
scale.
CAM-7 enables very high energy density as demonstrated by the data in Figures 1 and 2. Figure
1 shows the performance of 18650 cells fabricated at CAMX Power combining CAM-7 with
graphite and a low-temperature electrolyte to provide excellent energy density, both at room
temperature and lower temperatures. These 18650 cells were also independently evaluated at the
Army Research Laboratory as part of a Phase II SBIR program [1]. Figure 2 shows the
performance of a 1 Ah stacked-electrode pouch cell also fabricated at CAMX Power, combining
CAM-7 with a silicon-based anode and a tailored electrolyte. This cell can provide > 300 Wh/kg
at C/5 rate while also supplying ~ 270 Wh/kg at 5 C rate.
In this presentation, we will discuss the key performance attributes of CAM-7 relative to
commercial cathode materials, with a particular emphasis on the attractiveness of CAM-7 for
DoD applications. We will highlight the energy density improvement that can be achieved over
COTS Li-ion cells. We will also show performance data on CAMX Power’s prototype cells
showcasing the unique advantages of CAM-7 for DoD applications.
4.3
a
3.9
Voltage (V)
3.7
3.5
3.3
3.1
Specific Energy (Wh/kg)
247
2.9
Energy Density (Wh/L)
610
2.7
Specific Energy, Jelly Roll (Wh/kg)
Energy Density, Jelly Roll (Wh/L)
290
710
b
300
Specific Energy (Wh/kg)
4.1
250
200
150
100
50
0
RT
2.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
-30°C
-40°C
Operating Temperature
Capacity (Ah)
Figure 1: (a) Discharge curves for five high energy CAM-7/graphite 18650 cells fabricated at
CAMX Power. The inset box shows that the measured specific energy of the jelly roll itself
approaches 300 Wh/kg, but the heavy cell hardware limits the 18650 energy. (b) Measured
discharge energy density(C/10) at different temperatures shows that these 18650 cells can
support discharge even at -40ºC. A COTS cell with comparable room temperature specific
energy supported less than 10 Wh/kg at -30ºC and even less at -40ºC. Performance of our cells
was independently measured by the Army Research Laboratory [1].
4.2
4
C/5
3.8
1C
Voltage (V)
3.6
5C
3.4
3.2
48 x 30 x 4.7 mm pouch cells
3
2.8
2.6
2.4
2.2
2
0
30
60
90
120
150
180
210
240
270
300
Cell specific energy, Wh/kg
Figure 2: C-rate dependence of discharge specific energy for a 1.1 Ah, CAM-7/silicon, stackedelectrode pouch cell fabricated at CAMX Power. The inset shows a photograph of the cell and
the cell dimensions.
References:
[1]. Allen JL, Allen JL, Delp SA, Jow TR. (2014). Evaluation of TIAX High Energy CAM7/Graphite Lithium-Ion Batteries at High & Low Temperatures, U.S. Army Research Laboratory.