Battery Grade

Overview

There is a growing consensus that the world is moving towards a critical tipping point in the demand for electric and hybrid electric vehicles (EVs and HEVs). Given that these vehicles are powered largely by lithium-ion batteries, and that natural graphite is a key component in the anode portion of these batteries, it is widely expected that demand for graphite will increase significantly over the next ten years. To put this into perspective, the average EV or HEV will require approximately 1,000 individual battery cells per car. Each cell will contain approximately 14 grams of graphite, or about 13 new kilograms of graphite per vehicle. This is in addition to the many other items in a vehicle already using natural graphite.

As a result, given a modest annual increase in vehicle production over the next ten to fifteen years; allowing for a reasonable conversion to EVs and HEVs; and taking into account the battery replacement processes that will occur as cars age, it is expected that annual global graphite requirements could increase as much as 500,000 tonnes per year. If you add in the current and expected export constraints from key suppliers such as China, it is completely understandable that graphite customers around the world are looking for alternate and stable suppliers such as MEGA Graphite.

Battery Categories

The natural graphite grades for use in the anode component must fall within the range of specifications shown in the table below. A growing requirement is that the graphite be milled into a potato shaped material as much as possible to improve compaction and density within the battery compartment. MEGA Graphite has the full capability of producing this graphite to meet the demanding needs of battery manufacturers.

GRAPHITE GRADE
PARTICLE SIZE
d90(um)
PARTICLE SHAPE ASH (%) SCOTT DENSITY
g/m3
SPECIFIC BET SURFACE AREA
m2/g
MGN30 32 Potato Shaped 0.06 0.32 7
MGN50 45 Potato Shaped 0.06 0.40 6

Graphite powder additives used in these battery applications improves the electrical conductivity and the compression of the cathode mass, and increases the mechanical stability and process-ability of the cathode rings. In addition, lubricating properties reduce tool wear in the manufacturing process of the cathode rings and the high purity of the graphite powders helps minimize "gassing” in the cell. The graphite powder additive used in these applications improves the electrical conductivity and the compression of the cathode mass, and increases the mechanical stability and process-ability of the cathode rings. In addition, lubricating properties reduce tool wear in the manufacturing process of the cathode rings and the high purity of the graphite powders helps minimize "gassing” in the cell. The tables that follow describe a number of the benefits, characteristics and specifications for natural graphite use in primary and secondary batteries.

SEM of MEGA Graphite’s
Potato-shaped Product

NOTE: Both SEM photographs were taken prior to
final particle filtering.

Secondary filtering would create an even more uniform particle size.

Lithium-Ion (Li-I) batteries

Lithium-Ion batteries have become a standard component in a host of consumer and commercial products. Today they are found in everything from power tools and children’s toys to laptop computers and smart phones. As the world has sought to reduce its dependence on fossil fuels, electric vehicles (EV) powered by Li-I batteries have also become an increasingly important part of automotive development. The ability to charge rapidly, permit acceleration and work in hybrid environments has made Li-I technology a key part of the world’s energy future. The batteries themselves typically contain four basic elements: an anode, a cathode, electrolytes and separators. It is the anode where natural graphite is used, with each Li-I cell normally containing approximately 14 grams of natural graphite, and an average EV using upwards of a thousand cells. As new EV development occurs, and cell replacement also becomes a fact of life, the growth of this sector will represent a significant new opportunity for the natural graphite industry.

LITHIUM-ION BATTERIES - Graphite used in negative electrode as a host for Lithium, and in positive electrode as an electrically conductive additive.
PRODUCT FEATURES PRODUCT RANGE
Benefits Characteristics Selected Graphite Graphite Combination
Spherical Graphite

ANODE

  • High capacity
  • High stability
  • High adhesion and easy processing
  • High rate capability

CATHODE

  • High electrical conductivity
  • Good electrolyte absorbtion
  • Chemical stability

ANODE

  • High purity
  • High crystallinity
  • Defined particle morphology
  • Defined particle size distribution

CATHODE

  • High purity
  • High crystallinity
High purity, high crystallinity natural graphite milled and classified with high degree of delamination.
Combination of high purity graphite with, carbon black, and others so as to achieve high performance.

High purity flake graphite, with spheroidal particle shape (Mango shaped), high packing density, low surface area.

Defined particle size distributions in the range of d50 10 micron to d50 20 micron.

Special surface treatment to increase stability.

Primary and Secondary Batteries

Primary battery products such as zinc-carbon and alkaline (manganese dioxide) batteries, as well as secondary rechargeable alkaline manganese (RAM) batteries utilize graphite as the cathode material.

The graphite powder additive used in these applications improves the electrical conductivity and the compression of the cathode mass, and increases the mechanical stability and process-ability of the cathode rings. In addition, lubricating properties reduce tool wear in the manufacturing process of the cathode rings and the high purity of the graphite powders helps minimize "gassing” in the cell.

 

PRIMARY ALKALINE BATTERIES - Graphite used as a conductive additive, lubricant, and processing aid in the cathode.
PRODUCT FEATURES PRODUCT RANGE
Benefits Characteristics Standard Graphite Selected Graphite Graphite Combination Expanded Graphite
  • Excellent electrical conductivity
  • High lubricity in order to reduce tool wear
  • Compressibility for high mechanical strength
  • Chemical stability
  • High purity
  • High crystallinity
  • Defined particle morphology
  • Defined particle size distribution
High purity, high crystallinity natural graphite powder with defined particle size distributions in the range 10 microns up to 44 microns.
Purity: >99.95 % C.

High purity, high crystallinity natural graphite milled and classified with high degree of delamination.
Combination of high purity graphite with expanded graphite, carbon black and others so as to achieve high performance in special applications.
High purity expanded graphite with defined particle size distributions in the range of 10 to 50 microns.
RECHARGEABLE ALKALINE BATTERIES - Graphite is used in the positive electrode as an electrically conductive additive.
PRODUCT FEATURES PRODUCT RANGE
Benefits Characteristics Standard Graphite Selected Graphite Graphite Combination Expanded Graphite
  • High electrical conductivity
  • Good corrosion stability
  • No contamination with trace elements
  • High purity
  • High crystallinity
  • Defined particle morphology
  • Defined particle size distribution


High purity, high crystallinity natural graphite milled and classified with high degree of delamination.

 


High purity expanded graphite with defined particle size distributions in the range of 10 to 50 microns.

 

LEAD ACID BATTERIES - Graphite is used in the positive and negative electrode as an electrically conductive additive.
PRODUCT FEATURES PRODUCT RANGE
Benefits Characteristics Standard Graphite Selected Graphite Graphite Combination Expanded Graphite
  • Improved charge acceptance
  • Extended cycle life
  • High purity
  • High crystallinity
  • Defined particle morphology
  • Defined particle size distribution
High purity, high crystallinity natural graphite powder with defined particle size distributions in the range 5 microns up to 44 microns.
Purity: >99.95 % C.
High purity, high crystallinity natural graphite milled and classified with high degree of delamination.
Combination of high purity graphite with expanded graphite, carbon black and others so as to achieve high performance in special applications.
High purity expanded graphite with defined particle size distributions in the range of 10 to 50 microns.

Battery Production

A major breakthrough in the manufacture of premium performance batteries was the development of purified expanded graphite synthesized from purified natural flake graphite. A chemical is intercalated into the raw feedstock which is then exposed to rapid heat shock at about 1,000ºC. This leads to evaporation of the chemical from the bulk graphite, causing the flake to separate into the vermiform accordion shaped macromolecules. The numerous breaks on the surface of each particle serve as additional contact points when the graphite is combined in electrode matrixes. Better contact or "connectivity” of the conductive medium with the electrode active material results in increased electrode matrix conductivity, better electrode utilization, and improved premium cell performance. As shown on the process flow diagrams below, battery production is multi-stage process. The subsequent diagram also illustrates the battery production process within the overall automotive energy system process.