THE EDGE
wWhy are lithium batteries needed?
Lead-acid batteries have dominated the
communications industry for decades.
But due to disadvantages such as a short
cycle life, large size, high requirements on
load-bearing capacity and environmental
pollution in the production process, the
development of lead-acid batteries is
shrinking in several countries.
Indeed, telecom giant, China Tower, has
even decided to halt bids for lead-acid
batteries. Lithium batteries offer several
advantages, such as high energy density,
a small footprint and a long cycle life. As
the market share of lead-acid batteries
decreases rapidly, lithium battery usage
is increasing around the globe. Lithium
batteries are used in almost all 5G sites,
alongside their wide use in the data
centres of some large ISPs outside China.
The market share of lithium batteries
is predicted to approach or exceed that
of lead-acid batteries in the next three
to five years. It is widely agreed that
lithium batteries will dominate the market
in the future.
Basic concepts for
lithium batteries
Working principle
Typically, a lithium-ion battery uses lithium
alloy metal oxide as the cathode material,
graphite as the anode material and
contains non-aqueous electrolytes.
Cathode material: There are many
optional cathode materials. The
mainstream products are lithium
iron phosphate (LFP), nickel cobalt
manganese (NCM), or nickel cobalt
aluminum (NCA).
Anode material: Graphite is
predominantly used.
LFP battery example:
Cathode reaction: Lithium-ions are
embedded during discharge and
deintercalated during charge.
Charge: LiFePO4 → Li1-xFePO4 + xLi+ + xe-
Discharge: Li1-xFePO4 + xLi+ + xe- → LiFePO4
Anode reaction: Lithium-ions are
deintercalated during discharge and
embedded during charge
Charge: xLi+ + xe- + 6 C → LixC6
Discharge: LixC6 → xLi+ + xe- + 6 C
Battery classification (by
cathode material)
LiCoO 2
(LCO)
LiMnO 2
(LMO)
LiFePO 2
(LFP)
LiNiCoMnO 2
(NCM)
Which lithium batteries are
recommended for data centres?
Currently, mainstream lithium batteries in
the industry include LCO, LMO, LFP and
NCM batteries. LCO batteries are mainly
applied in the mobile phone battery
industry. LMO batteries are mainly used in
the electric bicycle industry. LFP batteries
are widely used in buses and energy
storage plants, while NCM batteries are
widely used in household vehicles, taxis
and energy storage plants. LFP and NCP
batteries are commonly used in data
centres. LFP batteries are more reliable,
while NCM batteries provide higher
energy density.
1. LFP batteries use a stable structure
LFP batteries use an olivine threedimensional
structure, while both LCO
and NCM batteries use a layered twodimensional
structure, which is easy to
collapse. The structure of LFP batteries is
more stable.
2. LFP batteries feature high thermal
stability as well as a low rate and
amount of heat yield
• LFP batteries are stable and
generate little heat in high
temperature environments. The peak
power output for heat yield is only
approximately 1 W.
• NCM batteries are prone to oxygen
evolution at high temperatures
or pressure, which increases the
burning possibility. The peak power
rate for heat yield is approximately
80 W/min. Explosive burning (within
seconds) can easily be triggered,
which is hard to control.
• The total heat generated by LFP
batteries is far lower than that of NCM
and LMO batteries (the area formed
by the heat yield power curve and
the horizontal axis represents the
total heat generated).
3. LFP batteries generate no
combustion accelerant in the case of
thermal runaway reaction
LFP batteries do not generate oxygen
after thermal runaway, while LMO, LCO
and NCM batteries do. Therefore, the
latter three are easier to catch fire.
LFP batteries cause thermal runaway
only at a high temperature, while LMO,
LCO and NCM batteries cause thermal
runaway at far lower temperatures.
Bottlenecks of lithium battery
application in data centres
Cost is a bottleneck, but cost reduction
will unlock potential.
www.intelligentdatacentres.com Issue 18
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