Ž.
Journal of Power Sources 74 1998 198–201
Secondary aqueous lithium-ion batteries with spinel anodes and cathodes
G.X. Wang
)
, S. Zhong, D.H. Bradhurst, S.X. Dou, H.K. Liu
Institute for Superconducting and Electronic Materials, UniÕersity of Wollongong, Northfields AÕenue, Wollongong, NSW, 2522, Australia
Received 14 January 1998; accepted 30 January 1998
Abstract
Secondary aqueous lithium-ion batteries with spinel Li Mn O or Li Mn O as the anode and LiMn O as the cathode are
249 4512 24
investigated. The aqueous electrolyte contains 6 M LiNO and 0.0015 M OH
y
. The Li Mn O rLiNO rLiMn O and
3249324
Li Mn O rLiNO rLiMn O aqueous cells deliver approximately 100 m Ah g
y
1
capacity at an average voltage of 1–1.1 V. This
4512 3 24
aqueous lithium-ion system eliminates safety concerns and offers considerably cost-effective technology for manufacturing. q 1998
Elsevier Science S.A. All rights reserved.
Keywords: Aqueous lithium-ion batteries; Spinel Li Mn O , Li Mn O and LiMn O ; Intercalation
2494512 24
1. Introduction
Secondary lithium-ion batteries are under extensive de-
velopment worldwide due to their high specific energy,
high voltage, and long shelf life. Such batteries are promis-
ing power sources for consumer electronics and electric
Ž.wx
vehicles EVs 1–4 . All of the present lithium technolo-
gies use non-aqueous electrolyte in which a lithium salt is
dissolved in an organic solvent. The conductivities of
organic electrolytes are typically two orders of magnitude
less than that of an aqueous system, which limits the rate
capacity and specific power. Usually, non-aqueous cells
must be assembled in an argon-filled chamber in which
oxygen and moisture have to be strictly excluded. Thus,
extra manufacturing costs are incurred.
The ‘rocking-chair’ concept takes advantage of the
difference in chemical potential of the lithium-ions in the
anode and cathode hosts. It is now understood that interca-
lation hosts in which the binding energy of lithium ions
differs by several eV can be coupled to construct a
lithium-ion cell. A variety of such systems has been devel-
oped with LiCoO , LiNiO , LiMn O as the cathode and
2224
carbonaceous materials or other intercalation compounds
wx
as the anode 5–8 .
Spinel lithiated oxide is an ideal host for lithium inser-
wx
tionrextraction due to its structural stability 9 . It is the
)
Corresponding author. Fax: q61-42-215731; e-mail:
guoxiu@uow.edu.au.
most promising electrode material for lithium-ion batteries.
Recently, it has been demonstrated that lithium ions can
intercalate into and de-intercalate from spinel LiMn O in
24
wx
aqueous electrolyte 10,11 . With spinels, however, the
following reaction can happen in aqueous solution.
Li A B qxHOmAB sqxLiOH aq
Ž. Ž .
x 24 2 24
qxr2H g 1
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2
q
Ž.
Concentrated Li can drive Eq. 1 to the left and thereby
cause the lithium intercalation compound to become stable
in aqueous solution. Consequently, it is theoretically possi-
ble for an aqueous secondary lithium battery to be made
with appropriate intercalation compounds.
wx
An aqueous lithium cell using VO B as the anode and
2
LiMn O as the cathode with an average voltage 1.5 V has
24
wx wx
been reported 12,13 , but the preparation of VO B is
2
tedious. In this paper, we have investigated aqueous
lithium-ion systems with spinel Li Mn O , or Li Mn O
249 4512
as the anode and LiMn O as the cathode that are struc-
24
turally stable compounds for the insertion and extraction of
lithium-ions.
2. Experimental
The electrode materials were synthesized via a solid-
state reaction at high temperature. The starting powders
were mixed by ball-milling in ethanol for 12 h. The
ethanol was evaporated. The samples were ground and
0378-7753r98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.
Ž.
PII S0378-7753 98 00057-3