"Nickel matt[e] is still an unknown low grade replacement for high grade nickel sulphides. Does it work for battery grade?"
As I understand it, no, it isn't and yes it does. That's, in part, precisely why deliverable LME- and SHFE- spec (99.8% pure) spot Ni pricing is depressed; why the traditional exchange-deliverable Ni inventories are ticking up; and why WA Ni sulphide producers are going to hell in a hand basket. Put another way, innovation has created an economically viable alternative processing pathway for intermediate Ni to supply the battery production market with matte from laterites without the need for more traditional, or costly, refining into 99.8% pure (Class 1) Ni.
Remember, the traditional mining->conc.->smelting (matte)->refining flow sheet model (that produces LME-deliverable 99.8% pure metal) was built around supplying the s/steel market. Until quite recently Ni used in the battery market could only be sourced in this way (i.e. melted/dissolved from pure Ni metal for further processing into the battery-ready inputs). This, in part, is why BHP chose to tack-on its Ni sulphate plant next to its Kwinana refinery, in order to divert some of their output to produce an intermediate Ni product for the battery market. For them it made sense, given their existing vertically-integrated mine-to-finished Ni metal product business model.
When processing Ni for use in a battery-only use case there are now alternative processing pathways that can bypass the (more costly/inefficient) need for traditional refining. Until recently it was only considered viable to do this using sulphides. That's what the IGO/Wyloo tie-up is/was considering in due course. However, the met code that the Chinese have effectively cracked with their laterite-to-matte processes is what everyone is so worried about.
So, cheaper NPI to feed the s/steel market (Disruption 1.0 of the late-2000s) and now a cheaper intermediate Ni product (also from laterite) to feed the growing battery market (Disruption 2.0).
The quality of cheap (fire-prone) Li-ion batteries is a completely different issue and should be considered separately. That's not directly related to the laterite-to-matte pathway story per se. It's more an issue around choices made re- battery production and quality control. Just because something is made in China doesn't automatically mean it's junk. It will come down to the specifics of decisions made by different producers operating in different segments of the market. Cheap and nasty price-driven producers will more likely produce fire-prone junk than producers who focus on quality. For an example of excellence and stability of China-manufactured Li-ion batteries we can look to the high-end Apple and Samsung smartphones and tablets.
We agree on the deeply problematic environmental costs associated with many laterite ops in Indonesia. For much the same reason that Westerners continue to buy cheap clothing from (exploited) Bangladesh, I'm of the view that the West is v.unlikely to boycott purchasing Ni that can be traced back to the pollutive practices in Indonesia or wherever if we can get it more cheaply by turning a blind eye. It might sound cynical, but it's just my observation of the human condition. We talk a good game until it costs us more money to do so. Over time, however, I do think ongoing pressure from the West to Indonesia will probably yield some positive improvements on the environmental front. Unlikely to be at the speed the rich West would like, but it's difficult to complain too much if/when we're complicit in supporting the Indo/Sino value chain.
Finally, while I respect your right to hold a differing view, I don't believe that China is in as deep of an economic hole as you paint. Yes, they're over-built (real estate) via speculation and, yes, it looks like they've passed peak population. But, by sheer weight of numbers alone, I think China is still going to be an economic juggernaut until long after we're dead.
Circling back to WA Ni, I think there's a v.high risk that companies involved in WA's high-cost Ni sulphides will follow a similar path to other geographic centres/locations that were historically displaced by innovation or technological change. Sheffield's (UK) steel industry comes to mind.
(20min delay)