rGO deposited in stainless steel fiber felt as mass transfer barrier layer
for
m
-DMFC
Yufeng Zhang
*
, Rui Xue, Xuelin Zhang
**
, Jiaying Song, Xiaowei Liu
MEMS Center, Harbin Institute of Technology, Harbin 150001, China
article info
Article history:
Received 16 May 2015
Received in revised form
7 August 2015
Accepted 7 September 2015
Available online 27 September 2015
Keywords:
Micro-direct methanol fuel cell
Graphene
Stainless steel fiber felt
Methanol mass transfer
abstract
In this paper, a novel anode mass transfer barrier layer was developed for
m
-DMFC (micro direct
methanol fuel cell) to decrease methanol crossover. The novel barrier layer was a composite material of
SSFF (stainless steel fiber felt) and rGO (reduced graphene oxide), which was prepared by dipping a piece
of SSFF plate into graphene oxide solution and subsequently experiencing a reduction process. Using this
composite material as anode barrier layer and current collector at the same tim e, a passive
m
-DMFC was
fabricated and tested. The results show that the novel barrier layer can effectively increase the methanol
mass transport resistance, which lowers the methanol crossover and thus allows the cell operating at a
high methanol concentration. In addition, the cell fabricated with the novel barrier layer shows higher
discharging stability and smaller inner resistance at the same time when compared with the conven-
tional cell.
© 2015 Elsevier Ltd. All rights reserved.
1. Introduction
In the field of portable devices, fuel cells are moving towards
renewable and quick start properties [1]. As a new type of power
device,
m
-DMFC (micro direct methanol fuel cell,
m
-DMFC) has the
advantages over traditional energy forms, such as high energy
density, rich and low cost sources, easy to store with high safety,
simple system structure, and convenient operation condition,
which will be widely used in aerospace, military, communication
and other fields [2e5]. The early studies on
m
-DMFC mainly aimed
at the structure, fluid heat and mass transfer characteristics of gas
diffusion layer. Water management and methanol crossover are the
most worthy on studying points in the field of PEMFC (proton ex-
change membrane fuel cell). On the cathode side, Carton has
analyzed water slug formation and droplet accumulation in the
flow channels in detail [6]. However, due to methanol crossover,
passive
m
-DMFC usually works under low concentration condition,
as a result leading to a poor power density [7,8]. In order to
commercialize the passive type of
m
-DMFC, lots of scientists have
made great efforts to improve the passive
m
-DMFC performance
previously [9e12].
Considering the internal structure and mass transfer charac-
teristics of
m
-DMFC, we need to reduce the methanol transport rate
by adding a barrier layer between the anode catalyst layer and the
anode methanol reservoir. Previously, stainless steel fiber felt has
been applied in cathode diffusion layer [13]. In aspect of anode side,
kinds of microporous metal plates have been used to alleviate the
effect of methanol crossover. Wu et al. incorporate a porous tita-
nium plate as a methanol mass transfer barrier and current col-
lectors, which has exhibited a power density as high as
40 mW cm
2
operating with neat methanol at 298 K [14]. Yuan
et al. developed a PMFSP (porous metal fiber sintered plate) as the
methanol barrier at the anode in order to alleviate the methanol
crossover [15]. The above researches are belonging to adding
additional layer between current collector and fuel reservoir,
therefore integration is not achieved.
In addition to the above materials reported, recently a two-
dimensional carbon nano structure media with the thickness of
only one atom named graphene, has attracted much attention
owing to its excellent electrical conductivity and high speci fi c
surface area [16]. In the fields of DMFC, the current researches
mainly focus on applying graphene as catalyst supporter [17,18].Xu
deposited Pt onto graphene, finding that the effect of Pt-graphene
catalyst is much better than that of Pt-carbon [19]. While there
are several groups of researchers have already started to try
different methods for preparation of graphene gel and porous
metal nanocomposite [20e22]. Yao Chen adopted electrophoretic
* Corresponding author. Tel.: þ86 0451 86413451; fax: þ86 0451 86413441.
** Corresponding author.
E-mail addresses: yufeng_zhang@hit.edu.cn (Y. Zhang), zhangxuelin@hit.edu.cn
(X. Zhang).
Contents lists available at ScienceDirect
Energy
journal homepage: www.elsevier.com/locate/energy
http://dx.doi.org/10.1016/j.energy.2015.09.026
0360-5442/© 2015 Elsevier Ltd. All rights reserved.
Energy 91 (2015) 1081e1086